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Introduction: Sacrococcygeal chordomas have high recurrence rates and are challenging to treat., Methods: In this phase II prospective, randomized, stratified trial, the safety and feasibility of hypofractionated ion radiation therapy were investigated. The primary focus was monitored through the incidence of Grade 3-5 NCI-CTC-AE toxicity. Secondary endpoints included local progression-free (LPFS) and overall survival (OS)., Results: The study enrolled 82 patients with primary (87 %) and recurrent (13 %) inoperable or incompletely resected sacral chordomas from January 2013 to July 2022, divided equally into proton therapy (Arm A) and carbon ion beam therapy (Arm B) groups, each receiving a total dose of 64 Gy (RBE) in 16 fractions, 5-6 fractions per week. Overall 74 % of patients received no previous surgery and 66 % of tumors were confirmed by a brachyury staining. The mean and median Gross Tumor Volume at the time of treatment (GTV) was 407 ml and 185 ml, respectively. The median follow-up of the surviving patients was 44.7 months, and the 2-year and 4-year OS rates were 96 % and 81 %, respectively. Factors such as smaller GTV and younger age trended towards better OS. The LPFS after 2-year and 4-year was 84 % and 70 %, respectively. Male gender emerged as a significant predictor of LPFS. There was no significant difference between the treatment groups. We observed five grade 4 wound healing disorders (6 %)., Conclusion: The initial response rates were promising; however local control was not sustained. More comparative research on fractionation schemes is essential to refine treatment approaches for inoperable sacral chordoma., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Background and Purpose: To investigate the toxicity and survival outcomes of proton and carbon ion radiotherapy for patients with operable early-stage lung cancer who are eligible for lobectomy., Materials and Methods: This multicenter nationwide prospective cohort study included patients with operable early-stage lung cancer. Proton and carbon ion radiotherapy was performed according to the schedule stipulated in the unified treatment policy. Progression-free survival (PFS), overall survival (OS) and treatment-related toxicities were evaluated., Results: A total of 274 patients were enrolled and included in efficacy and safety analyses. The most common tumor type was adenocarcinoma (44 %), while 105 cases (38 %) were not histologically confirmed or diagnosed clinically. Overall, 250 (91 %) of the 274 patients had tumors that were peripherally situated, while 138 (50 %) and 136 (50 %) patients were treated by proton and carbon ion radiotherapy, respectively. The median follow-up time for all censored patients was 42.8 months (IQR 36.7-49.0). Grade 3 or severe treatment-related toxicity was observed in 4 cases (1.5 %). Three-year PFS was 80.5 % (95 % CI: 75.7 %-85.5 %) and OS was 92.5 % (95 % CI: 89.3 %-95.8 %). Pathological confirmation and clinical stage were factors significantly associated with PFS, while tumor location and particle-ion type were not. Meanwhile, clinical stage was significantly associated with OS, but pathological confirmation, tumor location, and particle-ion type were not., Conclusions: Particle therapy for operable early-stage lung cancer resulted in excellent 3-year OS and PFS in each subset. In this disease context, proton and carbon ion beam therapies are feasible alternatives to curative surgery., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that would directly affect the research reported in this paper. Hideyuki Harada received Honoraria from Astrazeneca, Accuray, Chugai pharmaceutical, Takeda pharmaceutical, MSD, Eizai pharmaceutical, Phizer, Brainlab, Hitachi, Novartis, Guerbet Japan, GE Healthcare, Nihon Medi-Physics and Taiho pharmaceutical outside this work. Keita Mori received Honoraria from Chugai Pharmaceutical, Ono Pharmaceutical, Bristol Myers Squibb, Daiichi-Sankyo and Eli Lilly Japan outside this work. Hitoshi Ishikawa received Honoraria from Boston Scientific Corporation and MSD outside this work. Masaki Nakamura received Honoraria from Astrazeneca outside this work. Nobuteru Kubo received Honoraria from Astrazeneca outside this work. Miyako Satouchi received Honoraria from Chugai pharmaceutical, Astrazeneca,Eli Lilly Japan, Ono pharmaceutical, Bristol-Myers Squibb, MSD, Merck Janssen Pharmaceutical, Amgen, Taiho pharmaceutical, Pfizer, Daiichi-Sankyo, Eisai, Takeda pharmaceutical, Novartis, GlaxoSmithKline Consumer Healthcare Japan and Bayer pharmaceutical and research funding from GlaxoSmithKline, AstraZeneca, MSD, Janssen, Amgen, Taiho pharmaceutical, Ono pharmaceutical, Bristol Myers Squibb, Pfizer, Daiichi-Sankyo, and Eisai outside this work. Yoshiyuki Shioyama received Honoraria from Astrazeneca outside this work., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Purpose: Craniopharyngiomas (CPs) are rare tumors of the sellar region often leading to significant comorbidities due to their close proximity to critical structures. The aim of this study was to analyze survival outcome and late toxicities after surgery and proton beam therapy (PBT) in childhood CPs., Methods and Materials: Within the prospective registry study "KiProReg" (DRKS0000536), data of 74 childhood patients with CP, receiving PBT between August 2013 to June 2022 were eligible. Late toxicities were analyzed according to the grading system of the Common Terminology Criteria for Adverse Events, version 4.0., Results: Median follow-up since first diagnosis was 4.3 years (range, 0.8-14.7). In addition, 75.7% of patients received PBT at time of disease progression or recurrence, whereas 24.3% as part of their primary therapy (definitive or adjuvant). Predominantly (85.1%), pencil beam scanning technique was used. The median total dose and initial tumor volume were 5400 cGy relative biologic effectiveness (RBE) and 17.64 cm³ (range, 3.07-300.59), respectively. The estimated (±SE) 3-year overall survival, progression-free, and cystic failure-free survival rate after PBT were 98.2% (±1.7), 94.7% (±3.0), and 76.8% (±5.4), respectively. All local failures (n = 3) were in-field relapses necessitating intervention and occurred exclusively in patients receiving PBT at progression or recurrence. Early cystic enlargements after PBT were typically asymptomatic and self-limiting. Fatigue, headaches, vision disorders, obesity, and endocrinopathies were the predominant late toxicities. No high-grade (≥3) new-onset visual impairment or cognitive deterioration occurred compared with baseline. The presence of cognitive impairments at the end of follow-up correlated with size of the planning target volume (P = .034), D mean dose to the temporal lobes (P = .032, P = .045) and the number of surgical interventions before PBT (P = .029)., Conclusions: Our findings demonstrate favorable local control rates using modern PBT with acceptable late toxicities. Cyst growth within 12 months after radiation therapy is typically not associated with tumor progression. Longer follow-up must be awaited to confirm results., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Purpose: To report the outcomes of a large series of intracranial meningiomas (IMs) submitted to proton therapy (PT) with curative intent., Methods: We conducted a retrospective analysis on all consecutive IM patients treated between 2014 and 2021. The median PT prescription dose was 55.8 Gy relative biological effectiveness (RBE) and 66 GyRBE for benign/radiologically diagnosed and atypical/anaplastic IMs, respectively. Local recurrence-free survival (LRFS), distant recurrence-free survival (DRFS), overall survival (OS), and radionecrosis-free survival (RNFS) were evaluated with the Kaplan-Meier method. Univariable analysis was performed to identify potential prognostic factors for clinical outcomes. Toxicity was reported according to the latest Common Terminology Criteria for Adverse Events (CTCAE) version 5.0., Results: Overall, 167 patients were included. With a median follow-up of 41 months (range, 6-99), twelve patients (7%) developed tumor local recurrence after a median time of 39 months. The 5-year LRFS was 88% for the entire cohort, with a significant difference between benign/radiologically diagnosed and atypical/anaplastic IMs (98% vs. 47%, p < 0.001); this significant difference was maintained also for the 5-year OS and the 5-year DRFS rates. Patients aged ≤ 56 years reported significantly better outcomes, whereas lower prescription doses and skull base location were associated with better RNFS rates. Two patients experienced G3 acute toxicities (1.2%), and three patients G3 late toxicities (1.8%). There were no G4-G5 adverse events., Conclusion: PT proved to be effective with an acceptable toxicity profile. To the best of our knowledge this is one of the largest series including IM patients submitted to PT., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background/purpose: Radiation is a key component in the treatment of central nervous system pure germinoma (PG) in children and adolescents. Proton therapy (PT) improves normal tissue sparing and potentially reduces adverse effects (AE). The aim of this study was to present the largest single institution experience utilizing PT for the management of PG., Materials Methods: We enrolled 35 non-metastatic patients with PG that were treated with PT at our institution between July 2007 - September 2021. Most received induction chemotherapy (n = 31, 89 %) and whole ventricular irradiation with an involved field boost (n = 29, 83 %). The most common total dose was 30 CGE (n = 18, 51.4 %). We utilized the cumulative incidence method to estimate local control (LC), freedom from distant metastases (FFDM), freedom from progression (FFP), and overall survival (OS). Treatment related toxicity was assessed per CTCAE version 5., Results: Median follow-up was 6.2 years (range, 0.9---15.2). The 10-year Kaplan-Meier estimates for LC, FFDM, FFP, and OS were 100 %, 100 %, 100 %, and 94 % respectively. The most common AE were hearing impairment requiring hearing aids (n = 3), transient hypersomnia requiring medication (n = 3), and new onset endocrinopathy (n = 1). Of the 23 evaluable patients ≥ 18 years old at last follow-up, 8 were high school graduates/in college, 8 college graduates, and 7 others gainfully employed., Conclusions: When utilized in modern multimodality treatment of non-metastatic PG, the precise dosimetry of PT does not compromise disease control. Although serious radiation side effects are rare, the 100% cure rate supports further investigation into selective radiation dose and volume de-escalation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Purpose: Preclinical studies have shown a preferential normal tissue sparing effect of FLASH radiation therapy with ultra-high dose rates. The aim of the present study was to use a murine model of acute skin toxicity to investigate the biologic effect of varying dose rates, time structure, and introducing pauses in the dose delivery., Methods and Materials: The right hind limbs of nonanaesthetized mice were irradiated in the entrance plateau of a pencil beam scanning proton beam with 39.3 Gy. Experiment 1 was with varying field dose rates (0.7-80 Gy/s) without repainting, experiment 2 was with varying field dose rates (0.37-80 Gy/s) with repainting, and in experiment 3, the dose was split into 2, 3, 4, or 6 identical deliveries with 2-minute pauses. In total, 320 mice were included, with 6 to 25 mice per group. The endpoints were skin toxicity of different levels up to 25 days after irradiation., Results: The dose rate 50 , which is the dose rate to induce a response in 50% of the animals, depended on the level of skin toxicity, with the higher toxicity levels displaying a FLASH effect at 0.7-2 Gy/s. Repainting resulted in higher toxicity for the same field dose rate. Splitting the dose into 2 deliveries reduced the FLASH effect, and for 3 or more deliveries, the FLASH effect was almost abolished for lower grades of toxicity., Conclusions: The dose rate that induced a FLASH effect varied for different skin toxicity levels, which are characterized by a differing degree of sensitivity to radiation dosage. Conclusions on a threshold for the dose rate needed to obtain a FLASH effect can therefore be influenced by the dose sensitivity of the used endpoint. Splitting the total dose into more deliveries compromised the FLASH effect. This can have an impact for fractionation as well as for regions where 2 or more FLASH fields overlap within the same treatment session., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: The aim of this work was to investigate the ability of a biological oxygen enhancement ratio-weighted dose, D OER , to describe acute skin toxicity variations observed in mice after proton pencil beam scanning irradiations with changing doses and beam time structures., Methods and Materials: In five independent experiments, the right hind leg of a total of 621 CDF1 mice was irradiated previously in the entrance plateau of a pencil beam scanning proton beam. The incidence of acute skin toxicity (of level 1.5-2.0-2.5-3.0-3.5) was scored for 47 different mouse groups that mapped toxicity as function of dose for conventional and FLASH dose rate, toxicity as function of field dose rate with and without repainting, and toxicity when splitting the treatment into 1 to 6 identical deliveries separated by 2 minutes. D OER was calculated for all mouse groups using a simple oxygen kinetics model to describe oxygen depletion. The three independent model parameters (oxygen-depletion rate, oxygen-recovery rate, oxygen level without irradiation) were fitted to the experimental data. The ability of D OER to describe the toxicity variations across all experiments was investigated by comparing D OER -response curves across the five independent experiments., Results: After conversion from the independent variable tested in each experiment to D OER , all five experiments had similar MDD OER 50 (D OER giving 50% toxicity incidence) with standard deviations of 0.45 - 1.6 Gy for the five toxicity levels. D OER could thus describe the observed toxicity variations across all experiments., Conclusions: D OER described the varying FLASH-sparing effect observed for a wide range of conditions. Calculation of D OER for other irradiation conditions can quantitatively estimate the FLASH-sparing effect for arbitrary irradiations for the investigated murine model. With appropriate fitting parameters D OER also may be able to describe FLASH effect variations with dose and dose rate for other assays and endpoints., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The authors Lanke and Relander describe a patient with classical Hodgkin lymphoma (cHL) stage IIA, who had pain at alcohol consumption as the only symptom at diagnosis. The patient was treated with 4 cycles of ABVD chemotherapy and proton therapy 29.75 Gy (RBE). Apart from FDG-PET/CT the course of the disease was followed with serum-TARC. The case illustrates the value of knowing also rare symptoms at the general practice, the usefulness of TARC as a tumour marker in cHL, and the use of proton therapy in order to further reduce late radiotherapy side effects.

Purpose: Secondary breast cancer is a frequent late adverse event of mediastinal Hodgkin lymphoma radiotherapy. Secondary breast cancers overwhelmingly correspond to ductal carcinoma and develop from the glandular mammary tissue. In addition, during childhood, radiation overexposure of the glandular tissue may lead to a late breast hypotrophy at adult age. The aim of this study was to evaluate the radiation exposure to the glandular tissue in patients treated for mediastinal Hodgkin lymphoma with intensity-modulated proton therapy, in order to evaluate the potential dosimetric usefulness of its delineation for breast sparing., Materials and Methods: Sixteen consecutive intermediate-risk mediastinal female patients with Hodgkin lymphoma treated with consolidation radiation with deep inspiration breath hold intensity-modulated proton therapy to the total dose of 30Gy were included. Breasts were delineated according to the European Society for Radiotherapy and Oncology guidelines for treatment optimization ("clinical organ at risk"). The glandular tissue ("glandular organ at risk") was retrospectively contoured on the initial simulation CT scans based on Hounsfield unit (HU) values, using a range between -80HU and 500HU., Results: The mean and maximum doses delivered to the glandular organ at risk were significantly lower than the mean and maximum doses delivered to the clinical organ at risk, but were statistically correlated. Glandular organ at risk volumes were significantly smaller., Conclusion: Optimizing the treatment plans on the clinical breast contours will systematically lead to overestimation of the dose received to the glandular tissue and, consequently, to an indistinct and involuntary improved glandular tissue sparing. As such, our findings do not support the consideration of the glandular tissue as an additional organ at risk when planning intensity-modulated proton therapy for mediastinal Hodgkin lymphoma in female patients., (Copyright © 2024 The Author(s). Published by Elsevier Masson SAS.. All rights reserved.)

Purpose/objective: To perform a dosimetric and a normal tissue complication probability (NTCP) comparison between intensity modulated proton therapy and photon volumetric modulated arc therapy in a cohort of patients with parotid gland cancers in a post-operative or radical setting., Materials and Methods: From May 2011 to September 2021, 37 parotid gland cancers patients treated at two institutions were eligible. Inclusion criteria were as follows: patients aged ⩾ 18 years, diagnosis of parotid gland cancers candidate for postoperative radiotherapy or definitive radiotherapy, presence of written informed consent for the use of anonymous data for research purposes. Organs at risk (OARs) were retrospectively contoured. Target coverage goal was defined as D95 > 98%. Six NTCP models were selected. NTCP profiles were calculated for each patient using an internally-developed Python script in RayStation TPS. Average differences in NTCP between photon and proton plans were tested for significance with a two-sided Wilcoxon signed-rank test., Results: Seventy-four plans were generated. A lower Dmean to the majority of organs at risk (inner ear, cochlea, oral cavity, pharyngeal constrictor muscles, contralateral parotid and submandibular gland) was obtained with intensity modulated proton therapy vs volumetric modulated arc therapy with statistical significance (p < .05). Ten (27%) patients had a difference in NTCP (photon vs proton plans) greater than 10% for hearing loss and tinnitus: among them, seven qualified for both endpoints, two patients for hearing loss only, and one for tinnitus., Conclusions: In the current study, nearly one-third of patients resulted eligible for proton therapy and they were the most likely to benefit in terms of prevention of hearing loss and tinnitus., Competing Interests: Declaration of conflicting interestThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: The Division of Radiation Oncology of IEO received Institutional grants from Accuray InC. and Ion Beam Applications (IBA). BAJF received speakers’ fees from Roche, Bayer, Janssen, Carl Zeiss, Ipsen, Accuray, Astellas, Elekta, IBA and Astra Zeneca (all outside the current project). The remaining authors declare no conflicts of interest.

Purpose: Studies during the past 9 years suggest that delivering radiation at dose rates exceeding 40 Gy/s, known as "FLASH" radiation therapy, enhances the therapeutic index of radiation therapy (RT) by decreasing normal tissue damage while maintaining tumor response compared with conventional (or standard) RT. This study demonstrates the cardioprotective benefits of FLASH proton RT (F-PRT) compared with standard (conventional) proton RT (S-PRT), as evidenced by reduced acute and chronic cardiac toxicities., Methods and Materials: Mice were imaged using cone beam computed tomography to precisely determine the heart's apex as the beam isocenter. Irradiation was conducted using a shoot-through technique with a 5-mm diameter circular collimator. Bulk RNA-sequencing was performed on nonirradiated samples, as well as apexes treated with F-PRT or S-PRT, at 2 weeks after a single 40 Gy dose. Inflammatory responses were assessed through multiplex cytokine/chemokine microbead assay and immunofluorescence analyses. Levels of perivascular fibrosis were quantified using Masson's Trichrome and Picrosirius red staining. Additionally, cardiac tissue functionality was evaluated by 2-dimensional echocardiograms at 8- and 30-weeks post-PRT., Results: Radiation damage was specifically localized to the heart's apex. RNA profiling of cardiac tissues treated with PRT revealed that S-PRT uniquely upregulated pathways associated with DNA damage response, induction of tumor necrosis factor superfamily, and inflammatory response, and F-PRT primarily affected cytoplasmic translation, mitochondrion organization, and adenosine triphosphate synthesis. Notably, F-PRT led to a milder inflammatory response, accompanied by significantly attenuated changes in transforming growth factor β1 and α smooth muscle actin levels. Critically, F-PRT decreased collagen deposition and better preserved cardiac functionality compared with S-PRT., Conclusions: This study demonstrated that F-PRT reduces the induction of an inflammatory environment with lower expression of inflammatory cytokines and profibrotic factors. Importantly, the results indicate that F-PRT better preserves cardiac functionality, as confirmed by echocardiography analysis, while also mitigating the development of long-term fibrosis., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: Proton relative biological effectiveness (RBE) is a dynamic variable influenced by factors like linear energy transfer (LET), dose, tissue type, and biological endpoint. The standard fixed proton RBE of 1.1, currently used in clinical planning, may not accurately represent the true biological effects of proton therapy (PT) in all cases. This uncertainty can contribute to radiation-induced normal tissue toxicity in patients. In late-responding tissues such as the spinal cord, toxicity can cause devastating complications. This study investigated spinal cord tolerance in mice subjected to proton irradiation and characterized the influence of fractionation on proton- induced myelopathy at entrance (ENT) and Bragg peak (BP) positions., Methods and Materials: Cervical spinal cords of 8-week-old C57BL/6J female mice were irradiated with single- or multi-fractions (18x) using lateral opposed radiation fields at 1 of 2 positions along the Bragg curve: ENT (dose-mean LET = 1.2 keV/μm) and BP (LET = 6.9 keV/μm). Mice were monitored over 1 year for changes in weight, mobility, and general health, with radiation-induced myelopathy as the primary biological endpoint. Calculations of the RBE of the ENT and BP curve (RBE ENT/BP ) were performed., Results: Single-fraction RBE ENT/BP for 50% effect probability (tolerance dose (TD 50 ), grade II paresis, determined using log-logistic model fitting) was 1.10 ± 0.06 (95% CI) and for multifraction treatments it was 1.19 ± 0.05 (95% CI). Higher incidence and faster onset of paralysis were seen in mice treated at the BP compared with ENT., Conclusions: The findings challenge the universally fixed RBE value in PT, indicating up to a 25% mouse spinal cord RBE ENT/BP variation for multifraction treatments. These results highlight the importance of considering fractionation in determining RBE for PT. Robust characterization of proton-induced toxicity, aided by in vivo models, is paramount for refining clinical decision-making and mitigating potential patient side effects., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background and Purpose: This study evaluated long-term efficacy, safety, and changes in quality of life (QOL) of patients after image-guided proton therapy (IGPT) for operable stage I non-small cell lung cancer (NSCLC)., Materials and Methods: This single-institutional prospective phase 2 study enrolled patients with operable histologically confirmed stage IA or IB NSCLC (7th edition of UICC). The prescribed dose was 66 Gy relative biological effectiveness equivalents (GyRBE) in 10 fractions for peripheral lesions, or 72.6 GyRBE in 22 fractions for central lesions. The primary endpoint was the 3-year overall survival (OS). The secondary endpoints included disease control, toxicity, and changes in QOL score., Results: We enrolled 43 patients (median age: 68 years; range, 47-79 years) between July 2013 to January 2021, of whom 41 (95 %) had peripheral lesions and 27 (63 %) were stage IA. OS, local control, and progression-free survival rates were 95 % (95 % CI: 83-99), 95 % (82-99), and 86 % (72-94), respectively, at 3 years, and 83 % (66-92), 95 % (82-99), and 77 % (60-88), respectively, at 7 years. Four patients (9 %) developed grade 2, and one patient (2 %) developed grade 3 radiation pneumonitis. No other grade 3 or higher adverse events were observed. In the QOL analysis, global QOL remained favorable; however, approximately 40 % of patients reported dyspnea at 3 and 24 months., Conclusion: Our findings suggest that IGPT provides effective disease control and survival in operable stage I NSCLC, particularly for peripheral lesions. Moreover, toxicity associated with IGPT was minimal, and patients reported favorable QOL., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Introduction: An increase in plan robustness leads to a higher dose to organs-at-risk (OARs), and an increased chance of post-treatment toxicities. In contrast, more conformal plans lead to sparing of healthy surrounding tissue at the expense of a higher sensitivity to anatomical changes, requiring costly adaptations. In this study, we assess the trade-off and impact of treatment plan robustness on the adaptation rate., Method: Treatment planning was performed for 40 lung cancer patients, each having a planning 4DCT and up to eight weekly repeated 4DCTs (reCTs). For each patient, plans were made with three different levels of robustness based on setup uncertainty of 3, 6 and 9 mm. These plans were robustly re-evaluated on all reCTs to assess whether the clinical constraints were met., Results: For the 3, 6 and 9 mm robustness levels, adaptation rates of 87.5 %, 70.0 % and 57.5 %, respectively, were observed. A mean absolute normal tissue complication probability (NTCP) gain of 2.9 percentage points (pp) was calculated for pneumonitis grade ≥ 2 when transitioning from 9 mm plans to 3 mm plans, 7.6 pp for esophagitis grade ≥ 2, and 2.5 pp for mortality risk 2 years post-treatment., Conclusion: The lowered risk of post treatment toxicities at lower robustness levels is clinically relevant but comes at the expense of more treatment adaptations, particularly in cases where meeting our clinical goals is not compromised by having a dose that is more conformal to the target. The trade-off between workload and reduced NTCP needs to be individually assessed., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Infiltrative non-GBM gliomas are common primary intracranial malignancies, and postoperative adjuvant radiotherapy is recommended for most adult patients diagnosed with this disease to enhance local control and prolong intracranial progression-free survival (PFS). However, RT-related neurocognitive function (NCF) consequences should not be ignored. Early neurocognitive decline principally includes episodic memory, associated significantly with functions of the hippocampus. This prospective study aims to investigate the impact of adjuvant brain irradiation on neurocognitive performances and relevant oncological outcomes.Twenty-five patients with intracranial infiltrative non-GBM gliomas were enrolled when postoperative adjuvant RT was recommended. All recruited patients should receive baseline brain magnetic resonance imaging, and neuropsychological assessments before and 4 months after the RT course. A battery of neuropsychological measures, mainly including executive functions, memory, psychomotor speed and visuoconstructive ability, was used to evaluate NCFs of interest.Analyzing the delta values between post-irradiation and baseline NCF scores, we observed a robust trend reflecting cognitive stabilization rather than deterioration in almost all NCF. Both verbal and visual memory functions exhibited significant differences in the corresponding scaled scores ( Z  = -2.722, p = .006, regarding verbal memory; Z  = -2.246, p = .025, concerning non-verbal memory). Moreover, patients' neuropsychological performances associated with psychomotor speed and executive functions also disclosed a tendency toward stabilization/improvement.This prospective study demonstrated that patients with infiltrative non-GBM exhibited a marked tendency toward neurocognitive stabilization after receiving postoperative adjuvant RT. Clinical trial registration: Trial Registration with ClinicalTrials.gov identifier: NCT03534050.

Introduction: Re-irradiation (re-RT) for recurrent head and neck cancer (rHNC) is challenging. We describe clinical outcomes and toxicity of proton therapy (PT) for recurrent HNC, and report genomic alterations associated with patterns of failure., Materials & Methods: We performed a retrospective analysis of rHNC patients treated with PT. Outcomes were estimated using the Kaplan-Meier method. Univariate (UVA) and multivariate analyses (MVA) were performed to assess multiple patient factors. Next-generation sequencing and genomic analyses were performed on available samples., Results: Eighty-nine patients treated with PBS-PT for rHNC with a median follow-up of 12 mo (0-71 mo) were included. The 1- and 2-y local control (LC) rates were 80.8 % (95 % CI: 70.8-90.8) and 66.2 % (95 % CI: 50.7-81.7), and 1- and 2-y distant metastasis-free survival (DMFS) were 41.0 % (95 % CI: 30.0-52.0) and 26.3 % (95 % CI: 15.7-36.9). The median overall survival (OS) was 13 mo (95 % CI: 9.3-16.7). On UVA and MVA, smaller gross tumor volume (GTV) was associated with improved OS (HR 1.002, P = 0.004), DMFS (HR 1.002, P = 0.004), and PFS (HR 1.002, P = 0.014). There were 35 late Gr3 + toxicity events (30.3 %). Patients with higher candidate gene-specific mutation burden (genes with [OR] > 2, P < 0.05) had inferior PFS. TP53, NOTCH4, and ARID1B mutations were associated with inferior DMFS (OR > 2, P < 0.05)., Conclusions: PBS-PT is effective at achieving LC for rHNC with favorable toxicity. Distant metastases are common, and associated with TP53, NOTCH4, and ARID1B mutations. Inclusion of genomic alterations in the clinical decision process may be warranted., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Rebecca Krc: Membership Chair – the Society for Women in Radiation Oncology; Employment. William Mendes: No disclosures/COI other than employment Jason Molitoris: No disclosures/COI other than employment Matthew Ferris: No disclosures/COI other than employment Yang Song: No disclosures/COI other than employment Amol Shetty: NIH Grants (2U19 AI110820-08, 2R01 AI114800-07, DK 122682). Payments made to institution to cover %FTE support. Unrelated to content of this manuscript. Ranee Mehra: MERCK, institutional clinical trial involvement. Independent consultant for Coherus, Janssen, Astra Zeneca, Total Health US ESMO Update (meeting support), leadership roles (unpaid) for ECOG, NCI head and neck task force. John Papdimitriou: No disclosures/COI other than employment Kyle Hatten: No disclosures/COI other than employment Rodney Taylor: No disclosures/COI other than employment Jeffrey Wolf: No disclosures/COI other than employment Kai Sun: No disclosures/COI other than employment Soren Bentzen: No disclosures/COI other than employment William Regine: No disclosures/COI other than employment Phuoc Tran: Consultant for Natsar Pharm, Janssen-Taris Biomedical, Bayer Healthcare, and RefleXion, Personal fees from Noxopharm, Janssen-Taris Biomedical, Myovant and AstraZeneca Bayer Healthcare and RefleXion; Holds a patent 9114158-Compounds and Methods of Use in Ablative Radiotherapy licensed to Natsar Pharm. Matthew Witek: No disclosures/COI other than employment., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Purpose: This study aims to develop an ensemble machine learning-based (EML-based) risk prediction model for radiation dermatitis (RD) in patients with head and neck cancer undergoing proton radiotherapy, with the goal of achieving superior predictive performance compared to traditional models., Materials and Methods: Data from 57 head and neck cancer patients treated with intensity-modulated proton therapy at Kaohsiung Chang Gung Memorial Hospital were analyzed. The study incorporated 11 clinical and 9 dosimetric parameters. Pearson's correlation was used to eliminate highly correlated variables, followed by feature selection via LASSO to focus on potential RD predictors. Model training involved traditional logistic regression (LR) and advanced ensemble methods such as Random Forest and XGBoost, which were optimized through hyperparameter tuning., Results: Feature selection identified six key predictors, including smoking history and specific dosimetric parameters. Ensemble machine learning models, particularly XGBoost, demonstrated superior performance, achieving the highest AUC of 0.890. Feature importance was assessed using SHAP (SHapley Additive exPlanations) values, which underscored the relevance of various clinical and dosimetric factors in predicting RD., Conclusion: The study confirms that EML methods, especially XGBoost with its boosting algorithm, provide superior predictive accuracy, enhanced feature selection, and improved data handling compared to traditional LR. While LR offers greater interpretability, the precision and broader applicability of EML make it more suitable for complex medical prediction tasks, such as predicting radiation dermatitis. Given these advantages, EML is highly recommended for further research and application in clinical settings., (© 2024. The Author(s).)

Background: Nasopharyngeal adenoid cystic carcinoma (NACC) is a relatively rare salivary gland tumor that is generally associated with poor outcomes. High-dose radiotherapy is a key treatment for patients with NACC. This study reported the long-term efficacy and safety of particle beam radiation therapy (PBRT) for NACC., Methods and Materials: Twenty-six patients with nonmetastatic NACC who received definitive PBRT alone were included in this retrospective study. The majority of patients (92.3%) had locally advanced disease. Twenty-five (96.15%) patients received intensity-modulated proton radiotherapy (IMPT) followed by a carbon ion radiotherapy (CIRT) boost, and one patient received CIRT alone. Overall survival (OS), local control (LC), regional control (RC), and distant metastasis control (DMC) rates were calculated via the Kaplan-Meier method., Results: The median follow-up time was 46.95 months for the entire cohort. Seven patients experienced local recurrence, and one patient experience neck lymph node recurrence. The 3- and 4-year OS, LC, RC, and DMC rates were 100% and 91.7%, 92.3% and 84.6%, 95.8% and 87.8%, and 90.2% and 71.3%, respectively. A total of 91.3% of the patients achieved complete remission of gross tumors at 1 year after PBRT. Severe acute toxicity was observed in only two patients. A grade 4 decrease in visual acuity was observed in one patient with orbital apex invasion. No late grade 3 or 5 toxicity was observed., Conclusion: Definitive PBRT provided a satisfactory 4-year OS for patients with locally advanced NACC. The toxicity was acceptable and mild. Further follow-up is necessary to confirm the efficacy and safety of definitive PBRT for patients with NACC., (© 2024. The Author(s).)

Background and Purpose: Rare but severe toxicities of the optic apparatus have been observed after treatment of intracranial tumours with proton therapy. Some adverse events have occurred at unusually low dose levels and are thus difficult to understand considering dose metrics only. When transitioning from double scattering to pencil beam scanning, little consideration was given to increased dose rates observed with the latter delivery paradigm. We explored if dose rate related metrics could provide additional predicting factors for the development of late visual toxicities., Materials and Methods: Radiation-induced intracranial visual pathway lesions were delineated on MRI for all index cases. Voxel-wise maximum dose rate (MDR) was calculated for 2 patients with observed optic nerve toxicities (CTCAE grade 3 and 4), and 6 similar control cases. Additionally, linear energy transfer (LET) related dose enhancing metrics were investigated., Results: For the index cases, which developed toxicities at low dose levels (mean, 50 Gy RBE ), some dose was delivered at higher instantaneous dose rates. While optic structures of non-toxicity cases were exposed to dose rates of up to 1 to 3.2 Gy RBE /s, the pre-chiasmatic optic nerves of the 2 toxicity cases were exposed to dose rates above 3.7 Gy RBE /s. LET-related metrics were not substantially different between the index and non-toxicity cases., Conclusions: Our observations reveal large variations in instantaneous dose rates experienced by different volumes within our patient cohort, even when considering the same indications and beam arrangement. High dose rate regions are spatially overlapping with the radiation induced toxicity areas in the follow up images. At this point, it is not feasible to establish causality between exposure to high dose rates and the development of late optic apparatus toxicities due to the low incidence of injury., (© 2024. The Author(s).)

Introduction: It was hypothesized that use of proton beam therapy (PBT) in patients with locally advanced non-small cell lung cancer treated with concurrent chemoradiation and consolidative immune checkpoint inhibition is associated with fewer unplanned hospitalizations compared with intensity-modulated radiotherapy (IMRT)., Methods: Patients with locally advanced non-small cell lung cancer treated between October 2017 and December 2021 with concurrent chemoradiation with either IMRT or PBT ± consolidative immune checkpoint inhibition were retrospectively identified. Logistic regression was used to assess the association of radiation therapy technique with 90-day hospitalization and grade 3 (G3+) lymphopenia. Competing risk regression was used to compare G3+ pneumonitis, G3+ esophagitis, and G3+ cardiac events. Kaplan-Meier method was used for progression-free survival and overall survival. Inverse probability treatment weighting was applied to adjust for differences in PBT and IMRT groups., Results: Of 316 patients, 117 (37%) received PBT and 199 (63%) received IMRT. The PBT group was older (p < .001) and had higher Charlson Comorbidity Index scores (p = .02). The PBT group received a lower mean heart dose (p < .0001), left anterior descending artery V15 Gy (p = .001), mean lung dose (p = .008), and effective dose to immune circulating cells (p < .001). On inverse probability treatment weighting analysis, PBT was associated with fewer unplanned hospitalizations (adjusted odds ratio, 0.55; 95% CI, 0.38-0.81; p = .002) and less G3+ lymphopenia (adjusted odds ratio, 0.55; 95% CI, 0.37-0.81; p = .003). There was no difference in other G3+ toxicities, progression-free survival, or overall survival., Conclusions: PBT is associated with fewer unplanned hospitalizations, lower effective dose to immune circulating cells and less G3+ lymphopenia compared with IMRT. Minimizing dose to lymphocytes may be warranted, but prospective data are needed., (© 2024 American Cancer Society.)

Purpose: In this Pediatric Normal Tissue Effects in the Clinic (PENTEC) vision paper, challenges and opportunities in the assessment of subsequent neoplasms (SNs) from radiation therapy (RT) are presented and discussed in the context of technology advancement., Methods and Materials: The paper discusses the current knowledge of SN risks associated with historic, contemporary, and future RT technologies. Opportunities for research and SN mitigation strategies in pediatric patients with cancer are reviewed., Results: Present experience with radiation carcinogenesis is from populations exposed during widely different scenarios. Knowledge gaps exist within clinical cohorts and follow-up; dose-response and volume effects; dose-rate and fractionation effects; radiation quality and proton/particle therapy; age considerations; susceptibility of specific tissues; and risks related to genetic predisposition. The biological mechanisms associated with local and patient-level risks are largely unknown., Conclusions: Future cancer care is expected to involve several available RT technologies, necessitating evidence and strategies to assess the performance of competing treatments. It is essential to maximize the utilization of existing follow-up while planning for prospective data collection, including standardized registration of individual treatment information with linkage across patient databases., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Purpose: Previous comparative effectiveness studies have not demonstrated a benefit of proton beam therapy (PBT) compared with intensity-modulated radiation therapy (IMRT) for prostate cancer. An updated comparison of GI and genitourinary (GU) toxicity is needed., Methods: We investigated the SEER-Medicare linked database, identifying patients with localized prostate cancer diagnosed from 2010 to 2017. Procedure and diagnosis codes indicative of treatment-related toxicity were identified. As a sensitivity analysis, we also identified toxicity based only on procedure codes. Patients who underwent IMRT and PBT were matched 2:1 on the basis of clinical and sociodemographic characteristics. We then compared GI and GU toxicity at 6, 12, and 24 months after treatment., Results: The final sample included 772 PBT patients matched to 1,544 IMRT patients. The frequency of GI toxicity for IMRT versus PBT was 3.5% versus 2.5% at 6 months ( P = .18), 9.5% versus 10.2% at 12 months ( P = .18), and 20.5% versus 23.4% at 24 months ( P = .11). The frequency of only procedure codes indicative of GI toxicity for IMRT versus PBT was too low to be reported and not significantly different. The frequency of GU toxicity for IMRT versus PBT was 6.8% versus 5.7% ( P = .30), 14.3% versus 12.2% ( P = .13), and 28.2% versus 25.8% ( P = .21) at 6, 12, and 24 months, respectively. When looking only at procedure codes, the frequency of GU toxicity for IMRT was 1.0% at 6 months, whereas it was too infrequent to report for PBT ( P = .64). GU toxicity for IMRT versus PBT was 3.3% versus 2.1% ( P = .10), and 8.7% versus 6.7% ( P = .10) at 12 and 24 months, respectively., Conclusion: In this observational study, there were no statistically significant differences between PBT and IMRT in terms of GI or GU toxicity.

Background: High-level evidence on hypofractionated proton therapy (PT) for localized and locally advanced prostate cancer (PCa) patients is currently missing. The aim of this study is to provide a systematic literature review to compare the toxicity and effectiveness of curative radiotherapy with photon therapy (XRT) or PT in PCa., Methods: PubMed, Embase, and the Cochrane Library databases were systematically searched up to April 2022. Men with a diagnosis of PCa who underwent curative hypofractionated RT treatment (PT or XRT) were included. Risk of grade (G) ≥ 2 acute and late genitourinary (GU) OR gastrointestinal (GI) toxicity were the primary outcomes of interest. Secondary outcomes were five-year biochemical relapse-free survival (b-RFS), clinical relapse-free, distant metastasis-free, and prostate cancer-specific survival. Heterogeneity between study-specific estimates was assessed using Chi-square statistics and measured with the I2 index (heterogeneity measure across studies)., Results: A total of 230 studies matched inclusion criteria and, due to overlapped populations, 160 were included in the present analysis. Significant lower rates of G ≥ 2 acute GI incidence (2 % vs 7 %) and improved 5-year biochemical relapse-free survival (95 % vs 91 %) were observed in the PT arm compared to XRT. PT benefits in 5-year biochemical relapse-free survival were maintained for the moderate hypofractionated arm (p-value 0.0122) and among patients in intermediate and low-risk classes (p-values < 0.0001 and 0.0368, respectively). No statistically relevant differences were found for the other considered outcomes., Conclusion: The present study supports that PT is safe and effective for localized PCa treatment, however, more data from RCTs are needed to draw solid evidence in this setting and further effort must be made to identify the patient subgroups that could benefit the most from PT., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background and Purpose: Medulloblastoma (MB) is a common primary brain cancer in children. Proton therapy in pediatric MB is intensively studied and widely adopted. Compared to photon, proton radiations offer potential for reduced toxicity due to the characteristic Bragg Peak at the end of their path in tissue. The aim of this study was to compare the effects of irradiation with the same dose of protons or photons in Patched1 heterozygous knockout mice, a murine model predisposed to cancer and non-cancer radiogenic pathologies, including MB and lens opacity., Materials and Methods: TOP-IMPLART is a pulsed linear proton accelerator for proton therapy applications. We compared the long-term health effects of 3 Gy of protons or photons in neonatal mice exposed at postnatal day 2, during a peculiarly susceptible developmental phase of the cerebellum, lens, and hippocampus, to genotoxic stress., Results: Experimental testing of the 5 mm Spread-Out Bragg Peak (SOBP) proton beam, through evaluation of apoptotic response, confirmed that both cerebellum and hippocampus were within the SOBP irradiation field. While no differences in MB induction were observed after irradiation with protons or photons, lens opacity examination confirmed sparing of the lens after proton exposure. Marked differences in expression of neurogenesis-related genes and in neuroinflammation, but not in hippocampal neurogenesis, were observed after irradiation of wild-type mice with both radiation types., Conclusion: In-vivo experiments with radiosensitive mouse models improve our mechanistic understanding of the dependence of brain damage on radiation quality, thus having important implications in translational research., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: To evaluate the effects of local radiotherapy (RT) on growth, we evaluated the chronological growth profiles and vertebral features of children with high-risk neuroblastoma., Methods: Thirty-eight children who received local photon or proton beam therapy to the abdomen or retroperitoneum between January 2014 and September 2019 were included. Simple radiography of the thoracolumbar spine was performed before and every year after RT. The height and vertical length of the irradiated vertebral bodies (VBs) compared with the unirradiated VBs (vertebral body ratio, VBR) were analyzed using the linear mixed model. Shape feature analysis was performed to compare the irradiated and unirradiated vertebrae., Results: The follow-up was a median of 53.5 months (range, 21-81 months) after RT. A decline in height z-scores was mainly found in the early phase after treatment. In the linear mixed model with height, the initial height (fixed, p < 0.001), sex (time interaction, p = 0.008), endocrine dysfunction (time interaction, 0.019), and age at diagnosis (fixed and time interaction, both p = 0.002) were significant. Unlike the trend in height, the change in VBR (ΔVBR) decreased gradually (p < 0.001). The ΔVBR in the group that received more than 30 Gy decreased more than in the group that received smaller doses. In the shape feature analysis, the irradiated VBs changed to a more irregular surface that were neither round nor rectangular., Conclusion: The irradiated VBs in children were gradually restricted compared to the unirradiated VBs in long-term follow-up, and higher RT doses were significantly affected. Radiation-induced irregular features of VBs were observed., (© 2024. The Author(s).)

Objective. To evaluate the feasibility of using a deep learning dose prediction approach to identify patients who could benefit most from proton therapy based on the normal tissue complication probability (NTCP) model. Approach. Two 3D UNets were established to predict photon and proton doses. A dataset of 95 patients with localized prostate cancer was randomly partitioned into 55, 10, and 30 for training, validation, and testing, respectively. We selected NTCP models for late rectum bleeding and acute urinary urgency of grade 2 or higher to quantify the benefit of proton therapy. Propagated uncertainties of predicted ΔNTCPs resulting from the dose prediction errors were calculated. Patient selection accuracies for a single endpoint and a composite evaluation were assessed under different ΔNTCP thresholds. Main results. Our deep learning-based dose prediction technique can reduce the time spent on plan comparison from approximately 2 days to as little as 5 seconds. The expanded uncertainty of predicted ΔNTCPs for rectum and bladder endpoints propagated from the dose prediction error were 0.0042 and 0.0016, respectively, which is less than one-third of the acceptable tolerance. The averaged selection accuracies for rectum bleeding, urinary urgency, and composite evaluation were 90%, 93.5%, and 93.5%, respectively. Significance. Our study demonstrates that deep learning dose prediction and NTCP evaluation scheme could distinguish the NTCP differences between photon and proton treatment modalities. In addition, the dose prediction uncertainty does not significantly influence the decision accuracy of NTCP-based patient selection for proton therapy. Therefore, automated deep learning dose prediction and NTCP evaluation schemes can potentially be used to screen large patient populations and to avoid unnecessary delays in the start of prostate cancer radiotherapy in the future., (© 2024 Institute of Physics and Engineering in Medicine.)

This retrospective treatment-planning study was conducted to determine whether intensity-modulated proton therapy with robust optimization (ro-IMPT) reduces the risk of acute hematologic toxicity (H-T) and acute and late gastrointestinal toxicity (GI-T) in postoperative whole pelvic radiotherapy for gynecologic malignancies when compared with three-dimensional conformal radiation therapy (3D-CRT), intensity-modulated X-ray (IMXT) and single-field optimization proton beam (SFO-PBT) therapies. All plans were created for 13 gynecologic-malignancy patients. The prescribed dose was 45 GyE in 25 fractions for 95% planning target volume in 3D-CRT, IMXT and SFO-PBT plans and for 99% clinical target volume (CTV) in ro-IMPT plans. The normal tissue complication probability (NTCP) of each toxicity was used as an in silico surrogate marker. Median estimated NTCP values for acute H-T and acute and late GI-T were 0.20, 0.94 and 0.58 × 10-1 in 3D-CRT; 0.19, 0.65 and 0.24 × 10-1 in IMXT; 0.04, 0.74 and 0.19 × 10-1 in SFO-PBT; and 0.06, 0.66 and 0.15 × 10-1 in ro-IMPT, respectively. Compared with 3D-CRT and IMXT plans, the ro-IMPT plan demonstrated significant reduction in acute H-T and late GI-T. The risk of acute GI-T in ro-IMPT plan is equivalent with IMXT plan. The ro-IMPT plan demonstrated potential clinical benefits for reducing the risk of acute H-T and late GI-T in the treatment of gynecologic malignances by reducing the dose to the bone marrow and bowel bag while maintaining adequate dose coverage to the CTV. Our results indicated that ro-IMPT may reduce acute H-T and late GI-T risk with potentially improving outcomes for postoperative gynecologic-malignancy patients with concurrent chemotherapy., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Japanese Radiation Research Society and Japanese Society for Radiation Oncology.)

The usefulness of moderately hypofractionated radiotherapy for localized prostate cancer has been extensively reported, but there are limited studies on proton beam therapy (PBT) using similar hypofractionation schedules. The aim of this prospective phase II study is to confirm the safety of a shortened PBT course using 70 Gy relative biological effectiveness (RBE) in 28 fractions. From May 2013 to June 2015, 102 men with localized prostate cancer were enrolled. Androgen deprivation therapy was administered according to risk classification. Toxicity was assessed using Common Terminology Criteria for Adverse Events version 4.0. Of the 100 patients ultimately evaluated, 15 were classified as low risk, 43 as intermediate risk, and 42 as high risk. The median follow-up time of the surviving patients was 96 months (range: 60-119 months). The 5-year cumulative incidences of grade 2 gastrointestinal/genitourinary adverse events were 1% (95% CI: 0.1-6.9) and 4% (95% CI: 1.5-10.3), respectively; no grade ≥ 3 gastrointestinal/genitourinary adverse events were observed. The current study revealed a low incidence of late adverse events in prostate cancer patients treated with moderately hypofractionated PBT of 70 Gy (RBE) in 28 fractions, indicating the safety of this schedule., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Japanese Radiation Research Society and Japanese Society for Radiation Oncology.)

The aim of the present study was to report the feasibility of proton beam reirradiation for patients with locally recurrent rectal cancer (LRRC) with prior pelvic irradiation. The study population included patients who were treated with proton beam therapy (PBT) for LRRC between 2008 and December 2019 in our institution. Those who had a history of distant metastases of LRRC, with or without treatment, before reirradiation, were excluded. Overall survival (OS), progression-free survival (PFS) and local control (LC) were estimated using the Kaplan-Meier method. Ten patients were included in the present study. The median follow-up period was 28.7 months, and the median total dose of prior radiotherapy (RT) was 50 Gy (range, 30 Gy-74.8 Gy). The median time from prior RT to reirradiation was 31.5 months (range, 8.1-96.6 months), and the median reirradiation dose was 72 Gy (relative biological effectiveness) (range, 56-77 Gy). The 1-year/2-year OS, PFS and LC rates were 100%/60.0%, 20.0%/10.0% and 70.0%/58.3%, respectively, with a median survival time of 26.0 months. Seven patients developed a Grade 1 acute radiation dermatitis, and no Grade ≥ 2 acute toxicity was recorded. Grade ≥ 3 late toxicity was recorded in only one patient, who had developed a colostomy due to radiation-related intestinal bleeding. Reirradiation using PBT for LRRC patients who had previously undergone pelvic irradiation was feasible. However, the indications for PBT reirradiation for LRRC patients need to be considered carefully due to the risk of severe late GI toxicity., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Japanese Radiation Research Society and Japanese Society for Radiation Oncology.)

Background: Local control for patients with Ewing sarcoma (EWS) who present with large tumors are suboptimal when treated with standard radiation therapy (RT) doses of 54-55.8 Gy. The purpose of this study is to determine local control and toxicity of dose-escalated RT for tumors ≥8 cm (greatest diameter at diagnosis) in pediatric and young adult patients with EWS., Methods: Eligible patients ≤30 years old with newly diagnosed EWS ≥8 cm treated with definitive conformal or intensity modulated photon, or proton radiation therapy techniques were included. All patients in the study received dose-escalated RT doses. Outcomes included overall survival (OS), event-free survival (EFS), local failure rates, and toxicity., Results: Thirty-two patients were included, 20 patients presented with metastatic disease and 12 patients with localized disease. The median RT dose was 64.8 Gy (range, 59.4-69.4 Gy) with variability of doses to protect normal surrounding tissues. All patients received systemic chemotherapy. The 5-year OS and EFS for the cohort was 64.2% and 42%, respectively. The 5-year cumulative incidence of local failure was 6.6%. There were two combined local and distant failures with no isolated local failures. Twenty-nine patients experienced short term toxicity, 90% of those being radiation dermatitis. Twenty-seven patients experienced long-term toxicity, with only one experiencing grade 4 toxicity, a secondary malignancy after therapy., Conclusion: This study demonstrates that definitive RT for pediatric and young adult patients with EWS ≥8 cm provides high rates of local control, while maintaining a tolerable toxicity profile., (© 2024 American Cancer Society.)

Background/aim: This study aimed to compare the oncological outcomes of proton beam radiotherapy (PBT) with those of radiofrequency ablation (RFA) for newly diagnosed hepatocellular carcinoma (HCC)., Patients and Methods: This study included 323 patients who underwent PBT (n=40) or RFA (n=283) as a curative treatment for previously untreated HCC between October 2016 and June 2021. The primary endpoints were local progression and toxicity., Results: The median follow-up was 3.4 years (range=1.1-5.7 years). In terms of portal vein tumor thrombosis, tumor size, alpha-fetoprotein, and prothrombin-induced by vitamin K absence-II, the PBT group had significantly more severe tumor burdens than those of the RFA group (p<0.0001, p<0.0001, p=0.0004, and p<0.0001, respectively). No significant difference was observed in cumulative local progression rate (10.4% in PBT vs. 7.8% in RFA at 3-years, p=0.895). Grade 3 or higher toxicity was reported in only one patient (0.4%) after RFA. Multivariable analysis demonstrated that treatment modality was not a significant prognostic factor for local progression (hazard ratio=1.05; 95% confidence interval=0.32-3.48; p=0.934)., Conclusion: PBT demonstrated comparable local control with acceptable toxicity to RFA in newly diagnosed HCC. Therefore, PBT may be a valid alternative., (Copyright © 2024 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Purpose: Emerging evidence suggests proton radiation therapy may offer cognitive sparing advantages over photon radiation therapy, yet dosimetry has not been compared previously. The purpose of this study was to examine dosimetric correlates of cognitive outcomes in children with medulloblastoma treated with proton versus photon radiation therapy., Methods and Materials: In this retrospective, bi-institutional study, dosimetric and cognitive data from 75 patients (39 photon and 36 proton) were analyzed. Doses to brain structures were compared between treatment modalities. Linear mixed-effects models were used to create models of global IQ and cognitive domain scores., Results: The mean dose and dose to 40% of the brain (D40) were 2.7 and 4.1 Gy less among proton-treated patients compared with photon-treated patients (P = .03 and .007, respectively). Mean doses to the left and right hippocampi were 11.2 Gy lower among proton-treated patients (P < .001 for both). Mean doses to the left and right temporal lobes were 6.9 and 7.1 Gy lower with proton treatment, respectively (P < .001 for both). Models of cognition found statistically significant associations between higher mean brain dose and reduced verbal comprehension, increased right temporal lobe D40 with reduced perceptual reasoning, and greater left temporal mean dose with reduced working memory. Higher brain D40 was associated with reduced processing speed and global IQ scores., Conclusions: Proton therapy reduces doses to normal brain structures compared with photon treatment. This leads to reduced cognitive decline after radiation therapy across multiple intellectual endpoints. Proton therapy should be offered to children receiving radiation for medulloblastoma., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Classical Hodgkin lymphoma is a lymphoproliferative disease with a good prognosis mainly seen in young people. Nevertheless secondary malignancy, cardiac disease and infertility may affect the long survivors with significant impact on quality of life, morbidity and overall survival. In the last decades several treatment strategies were evaluated to reduce the toxicity of first line treatment such as avoiding radiotherapy or its reduction in terms of dosage and extension. Many trials including interim Positron Emission Tomography evaluation fail to compare efficacy between combined modality treatment versus chemotherapy alone in particular in early stage disease. In this review we analyze which subset of patients could take advantage from proton therapy in terms of toxicity and cost effectiveness., (© 2024 The Authors. Hematological Oncology published by John Wiley & Sons Ltd.)

Background: Unusual olfactory perception, often referred to as "phantosmia" or "cacosmia" has been reported during brain radiotherapy (RT), but is infrequent and does not typically interfere with the ability to deliver treatment. We seek to determine the rate of phantosmia for patients treated with proton craniospinal irradiation (CSI) and identify any potential clinical or treatment-related associations., Methods: We performed a retrospective review of 127 pediatric patients treated with CSI, followed by a boost to the brain for primary brain tumors in a single institution between 2016 and 2021. Proton CSI was delivered with passive scattering (PS) proton technique (n = 53) or pencil beam scanning technique (PBS) (n = 74). Within the PBS group, treatment delivery to the CSI utilized a single posterior (PA) field (n = 24) or two posterior oblique fields (n = 50). We collected data on phantom smell, nausea/vomiting, and the use of medical intervention., Results: Our cohort included 80 males and 47 females. The median age of patients was 10 years (range: 3-21). Seventy-one patients (56%) received concurrent chemotherapy. During RT, 104 patients (82%) developed worsening nausea, while 63 patients (50%) reported episodes of emesis. Of those patients who were awake during CSI (n = 59), 17 (29%) reported phantosmia. In the non-sedated group, we found a higher rate of phantosmia in patients treated with PBS (n = 16, 42%) than PS (n = 1, 4.7%) (p = .002). Seventy-eight patients (61%) required medical intervention after developing nausea/vomiting or phantosmia during RT. Two patients required sedation due to the malodorous smell during CSI. We did not find any significant difference in nausea/vomiting based on treatment technique., Conclusion: Proton technique significantly influenced olfactory perception with greater rates of phantosmia with PBS compared to PS. Prospective studies should be performed to determine the cause of these findings and determine techniques to minimize phantosmia during radiation therapy., (© 2024 Wiley Periodicals LLC.)

Background and Purpose: Ependymoma is the third most frequent childhood braintumor. Standard treatment is surgery followed by radiation therapy including proton therapy (PBT). Retrospective studies have reported higher rates of brainstem injury after PBT than after photon therapy (XRT). We report a national multicenter study of the incidence of brainstem injury after XRT versus PBT, and their correlations with dosimetric data., Material and Methods: We included all patients aged < 25 years who were treated with PBT or XRT for intracranial ependymoma at five French pediatric oncology reference centers between 2007 and 2020. We reviewed pre-irradiation MRI, follow-up MRIs over the 12 months post-treatment and clinical data., Results: Of the 83 patients, 42 were treated with PBT, 37 with XRT, and 4 with both (median dose: 59.4 Gy, range: 53‑60). No new or progressive symptomatic brainstem injury was found. Four patients presented asymptomatic radiographic changes (punctiform brainstem enhancement and FLAIR hypersignal), with median onset at 3.5 months (range: 3.0‑9.4) after radiation therapy, and median offset at 7.6 months (range: 3.7‑7.9). Two had been treated with PBT, one with XRT, and one with mixed XRT-PBT. Prescribed doses were 59.4, 55.8, 59.4 and 54 Gy., Conclusion: Asymptomatic radiographic changes occurred in 4.8% of patients with ependymoma in a large national series. There was no correlation with dose or technique. No symptomatic brainstem injury was identified., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Purpose: This study aimed to predict the probability of grade ≥2 pneumonitis or dyspnea within 12 months of receiving conventionally fractionated or mildly hypofractionated proton beam therapy for locally advanced lung cancer using machine learning., Methods and Materials: Demographic and treatment characteristics were analyzed for 965 consecutive patients treated for lung cancer with conventionally fractionated or mildly hypofractionated (2.2-3 Gy/fraction) proton beam therapy across 12 institutions. Three machine learning models (gradient boosting, additive tree, and logistic regression with lasso regularization) were implemented to predict Common Terminology Criteria for Adverse Events version 4 grade ≥2 pulmonary toxicities using double 10-fold cross-validation for parameter hyper-tuning without leak of information. Balanced accuracy and area under the curve were calculated, and 95% confidence intervals were obtained using bootstrap sampling., Results: The median age of the patients was 70 years (range, 20-97), and they had predominantly stage IIIA or IIIB disease. They received a median dose of 60 Gy in 2 Gy/fraction, and 46.4% received concurrent chemotherapy. In total, 250 (25.9%) had grade ≥2 pulmonary toxicity. The probability of pulmonary toxicity was 0.08 for patients treated with pencil beam scanning and 0.34 for those treated with other techniques (P = 8.97e-13). Use of abdominal compression and breath hold were highly significant predictors of less toxicity (P = 2.88e-08). Higher total radiation delivered dose (P = .0182) and higher average dose to the ipsilateral lung (P = .0035) increased the likelihood of pulmonary toxicities. The gradient boosting model performed the best of the models tested, and when demographic and dosimetric features were combined, the area under the curve and balanced accuracy were 0.75 ± 0.02 and 0.67 ± 0.02, respectively. After analyzing performance versus the number of data points used for training, we observed that accuracy was limited by the number of observations., Conclusions: In the largest analysis of prospectively enrolled patients with lung cancer assessing pulmonary toxicities from proton therapy to date, advanced machine learning methods revealed that pencil beam scanning, abdominal compression, and lower normal lung doses can lead to significantly lower probability of developing grade ≥2 pneumonitis or dyspnea., (Published by Elsevier Inc.)

Purpose: Intracerebral radiation-induced contrast enhancement (RICE) can occur after photon as well as proton beam therapy (PBT). This study evaluated the incidence, characteristics, and risk factors of RICE after PBT delivered to, or in direct proximity to, the brain and its effect on health-related quality of life (HRQoL)., Methods and Materials: Four hundred twenty-one patients treated with pencil beam scanning PBT between 2017 and 2021 were included. Follow-up included clinical evaluation and contrast-enhanced magnetic resonance imaging at 3, 6, and 12 months after treatment completion and annually thereafter. RICE was graded according to Common Terminology Criteria for Adverse Events version 4, and HRQoL parameters were assessed via European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ)-C30 questionnaires., Results: The median follow-up was 24 months (range, 6-54), and median dose to 1% relative volume of noninvolved central nervous system (D1%CNS) was 54.3 Gy relative biologic effectiveness (RBE; range, 30-76 Gy RBE). The cumulative RICE incidence was 15% (n = 63), of which 10.5% (n = 44) were grade 1, 3.1% (n = 13) were grade 2, and 1.4% (n = 6) were grade 3. No grade 4 or 5 events were observed. Twenty-six of 63 RICE (41.3%) had resolved at the latest follow-up. The median onset after PBT and duration of RICE in patients in whom the lesions resolved were 11.8 and 9.0 months, respectively. On multivariable analysis, D1%CNS > 57.6 Gy RBE, previous in-field radiation, and diabetes mellitus were identified as significant risk factors for RICE development. Previous radiation was the only factor influencing the risk of symptomatic RICE. After PBT, general HRQoL parameters were not compromised. In a matched cohort analysis of 54/50 patients with and without RICE, no differences in global health score or functional and symptom scales were seen., Conclusions: The overall incidence of clinically relevant RICE after PBT is very low and has no significant negative effect on long-term patient QoL., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Introduction: Adjuvant immunotherapy (IO) following concurrent chemotherapy and photon radiation therapy confers an overall survival (OS) benefit for patients with inoperable locally advanced non-small cell lung carcinoma (LA-NSCLC); however, outcomes of adjuvant IO after concurrent chemotherapy with proton beam therapy (CPBT) are unknown. We investigated OS and toxicity after CPBT with adjuvant IO versus CPBT alone for inoperable LA-NSCLC., Materials and Methods: We analyzed 354 patients with LA-NSCLC who were prospectively treated with CPBT with or without adjuvant IO from 2009 to 2021. Optimal variable ratio propensity score matching (PSM) matched CPBT with CPBT + IO patients. Survival was estimated with the Kaplan-Meier method and compared with log-rank tests. Multivariable Cox proportional hazards regression evaluated the effect of IO on disease outcomes., Results: Median age was 70 years; 71 (20%) received CPBT + IO and 283 (80%) received CPBT only. After PSM, 71 CPBT patients were matched with 71 CPBT + IO patients. Three-year survival rates for CPBT + IO vs CPBT were: OS 67% vs 30% (P < 0.001) and PFS 59% vs 35% (P = 0.017). Three-year LRFS (P = 0.137) and DMFS (P = 0.086) did not differ. Receipt of adjuvant IO was a strong predictor of OS (HR 0.40, P = 0.001) and PFS (HR 0.56, P = 0.030), but not LRFS (HR 0.61, P = 0.121) or DMFS (HR 0.61, P = 0.136). There was an increased incidence of grade ≥3 esophagitis in the CPBT-only group (6% CPBT + IO vs 17% CPBT, P = 0.037)., Conclusion: This study, one of the first to investigate CPBT followed by IO for inoperable LA-NSCLC, showed that IO conferred survival benefits with no increased rates of toxicity., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: Ocular surface disorder after ocular radiation therapy, even though commonly reported, is often overlooked. Any delay in diagnosis may lead to complications that threaten vision. The presented case highlights the clinical outcome of a severe post-radiation disorder of the ocular surface, the importance of intensive therapy, and the limitations of further surgical interventions., Case Presentation: A 34-year-old woman was referred for a second opinion due to a years-long history of pain and redness in her right eye (OD) after proton beam therapy for recurrent iris melanoma. The patient then developed post-radiation retinopathy with macula edema, secondary glaucoma, cataract, as well as a severe ocular surface disorder with corneal decompensation and band keratopathy. Several surgical treatments have been attempted, including phacoemulsification with IOL implantation and trabeculectomy with mitomycin C. Due to refractory glaucoma, Baerveldt glaucoma drainage was then necessary. Given the worsening clinical presentation of post-radiation ocular surface disorder with progressing band keratopathy, the possibility of penetrating keratoplasty (PKP) was discussed., Conclusion: The continuous worsening of clinical symptoms of the disorder of the ocular surface after proton beam radiotherapy can be the result of a post-radiation syndrome. Gradual expansion of ischemia, vasculitis, and inflammatory mediators compresses the retinal tissue, leading to recurrent macular edema as well as to secondary glaucoma and corneal decompensation. Band keratopathy is occasionally noted and seems to result from severe post-radiation disorder of the ocular surface. However, PKP would typically be indicated in cases of corneal perforation, uncontrolled infectious keratitis, or for improving vision in the presence of corneal opacification, none of which applied to our patient. Furthermore, post-radiation keratopathy implies compromised corneal stromal lymphogenesis and angiogenesis, both of which are now considered essential conditions for allograft rejection. Moreover, a previously performed Baerveldt glaucoma drainage surgery can affect the survival rate of the endothelial cells of the recipient cornea. Therefore, a penetrating or endothelial keratoplasty should be viewed as a high-risk procedure. In this instance, the rigorous treatment of the severe ocular surface disorder was crucial. We managed our patient's complex situation by following the latest guidelines set by the Tear Film & Ocular Surface Society and aimed to alleviate the symptoms as effectively as possible. In conclusion, careful decision-making regarding surgical treatment options should be considered, taking into account the complexities and potential risks involved., Competing Interests: The authors declare that they have no conflict of interest., (Thieme. All rights reserved.)

Cancer management is an expansive, growing, and evolving field. In the last decade or so, immunotherapy (IT) and particle beam therapy have made a tremendous impact in this domain. IT has already established itself as the fourth pillar of oncology. Recent emphasis has been centred around combination therapy, postulating additive or multiplicative effects of combining IT with one or more of the three conventional "pillars," that is, surgery, chemotherapy, and radiotherapy. Radio-IT is being increasingly explored and has shown promising outcomes in both preclinical and clinical settings. Particle beam therapy such as protons, when used as the radiotherapeutic modality in conjunction with IT, can potentially limit toxicities and improve this synergism further. Modern proton therapy has demonstrated a reduction in integral dose of radiation and radiation-induced lymphopenia in various sites. Protons, by virtue of their inherent clinically desirable physical and biological characteristics, namely, high linear energy transfer, relative biological effectiveness of range 1.1-1.6, and proven anti-metastatic and immunogenic potential in preclinical studies, might have a superior immunogenic profile than photons. Proton-IT combination is being studied currently by various groups in lung , head neck and brain tumors, and should be evaluated further in other subsites to replicate preclinical outcomes in a clinical setting. In this review, we summarize the currently available evidence for combinatorial approaches and feasibility of proton and IT combination, and thereafter highlight the emerging challenges for practical application of the same in clinics, while also proposing plausible solutions., (© 2023 John Wiley & Sons Australia, Ltd.)

Objectives: We sought to describe outcomes for locally advanced cutaneous squamous cell carcinoma (SCC) involving the parotid treated with volumetric modulated arc therapy (VMAT) versus pencil beam scanning proton beam therapy (PBT)., Materials and Methods: Patients were gathered from 2016 to 2022 from 5 sites of a large academic RT department; included patients were treated with RT and had parotid involvement by: direct extension of a cutaneous primary, parotid regional spread from a previously or contemporaneously resected but geographically separate cutaneous primary, or else primary parotid SCC (with a cutaneous primary ostensibly occult). Acute toxicities were provider-reported (CTCAE v5.0) and graded at each on treatment visit. Statistical analyses were conducted., Results: Median follow-up was 12.9 months (1.3 - 72.8); 67 patients were included. Positive margins/extranodal extension were present in 34 cases; gross disease in 17. RT types: 39 (58.2 %) VMAT and 28 (41.8 %) PBT. Concurrent systemic therapy was delivered in 10 (14.9 %) patients. There were 17 treatment failures (25.4 %), median time of 168 days. Pathologically positive neck nodes were associated with locoregional recurrence (p = 0.015). Oral cavity, pharyngeal constrictor, and contralateral parotid doses were all significantly lower for PBT. Median weight change was -3.8 kg (-14.1 - 5.1) for VMAT and -3 kg (-16.8 - 3) for PBT (p = 0.013). Lower rates of ≥ grade 1 xerostomia (p = 0.002) and ≥ grade 1 dysguesia (p < 0.001) were demonstrated with PBT., Conclusions: Cutaneous SCC involving the parotid can be an aggressive clinical entity despite modern multimodal therapy. PBT offers significantly lower dose to organs at risk compared to VMAT, which seemingly yields diminished acute toxicities., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: Proton and carbon-ion therapy may spare normal tissues in regions with many critical structures surrounding the target volume. As toxicity outcome data are emerging, we aimed to synthesize the published data for the toxicity outcomes of proton or carbon-ion therapy (together known as particle beam therapy [PBT]) for primary nasopharyngeal carcinoma (NPC)., Materials and Methods: We searched PubMed and Scopus electronic databases to identify original studies reporting toxicity outcomes following PBT of primary NPC. Quality assessment was performed using NIH's Quality Assessment Tool. Reports were extracted for information on demographics, main results, and clinical and dose factors correlates. Meta-analysis was performed using the random-effects model., Results: Twelve studies were selected (six using mixed particle-photon beams, five performed comparisons to photon-based therapy). The pooled event rates for acute grade ≥2 toxicities mucositis, dermatitis, xerostomia weight loss are 46% (95% confidence interval [95% CI]-29%-64%, I 2  = 87%), 47% (95% CI-28%-67%, I 2  = 87%), 16% (95% CI-9%-29%, I 2  = 76%), and 36% (95% CI-27%-47%, I 2  = 45%), respectively. Only one late endpoint (xerostomia grade ≥2) has sufficient data for analysis with pooled event rate of 9% (95% CI-3%-29%, I 2  = 77%), lower than intensity-modulated radiotherapy 27% (95% CI-10%-54%, I 2  = 95%). For most endpoints with significant differences between the PBT and photon-based therapies, PBT resulted in better outcomes. In two studies where dose distribution was studied, doses to the organs at risk were independent risk factors for toxicities., Conclusion: PBT may reduce the risk of acute toxicities for patients treated for primary NPC, likely due to dose reduction to critical structures. The pooled event rate for toxicities derived in this study can be a guide for patient counseling., (© 2023 John Wiley & Sons Australia, Ltd.)

Introduction and Objective: Proton beam therapy (PBT) provides the opportunity for a more localized delivery of high energy protons and may reduce the damage to healthy tissues and vital organs. The aim of this review was to assess the effects of proton therapy for patients diagnosed with Hodgkin or non-Hodgkin lymphoma treated with mediastinal irradiation., Review Methods: A systematic search of EMBASE, MEDLINE via OVID and Cochrane Library was conducted in May 2022 according to PRISMA guidelines to identify relevant data on the efficacy and toxicity of proton beam therapy for patients diagnosed with Hodgkin or non-Hodgkin lymphoma., Brief Description of the State of Knowledge: Of 566 screened abstracts (430 after de-duplication) 11 studies with a total of 529 patients were included. All studies were case series published between 2011-2021. Median range of follow-up time was 15-63.6 months. The overall survival (OS) for 2 years varied from 91% - 98% for 5 of the included studies. Three of the included studies had favourable outcomes with 2-year progression-free survival (PFS) ranging from 73% - 94%. Skin reaction, oesophagitis and fatigue were found to be the most common grade 1 and grade 2 toxicities. No acute or late grade 4 and higher toxicities/adverse events were observed., Summary: There are data indicating that PBT may to be an effective treatment against mediastinal Hodgkin and non-Hodgkin lymphoma. Because all the studies were case series, the authors of this review have little confidence in the evidence. There remains a need for well-designed randomized controlled trials to inform about the optimal approach to proton irradiation in HL and NHL.

A nationwide multicenter cohort study on particle therapy was launched by the Japanese Society for Radiation Oncology in Japan in May 2016. We analyzed the outcome of proton beam therapy (PBT) for liver oligometastasis in breast cancers. Cases in which PBT was performed at all Japanese proton therapy facilities between May 2016 and February 2019 were enrolled. The patients were selected based on the following criteria: the primary cancer was controlled, liver recurrence without extrahepatic tumors and no more than three liver lesions. Fourteen females, with a median age of 57 years (range, 44-73) and 22 lesions, were included. The median lesion size, fraction (fr) size and biological effective dose were 44 (20-130) mm, 6.6 (2-8) gray (Gy) (relative biological effectiveness)/fr and 109.6 (52.7-115.2) Gy, respectively. The median follow-up period was 22.8 (4-54) months. The 1-, 2- and 3-year local control (LC) rates of liver metastasis from breast cancer were 100% for all. The 1-, 2- and 3-year overall survival rates were 85.7, 62.5 and 62.5%, respectively. The 1-, 2- and 3-year progression-free survival (PFS) rates were 50.0%, 33.3%, and 16.7%, respectively. The median PFS time was 16 months. Only one patient did not complete PBT due to current disease progression. One patient had Grade 3 radiation-induced dermatitis. None of the patients experienced radiation-induced liver failure during the acute or late phase. Owing to the low incidence of adverse events and the high LC rate, PBT appears to be a feasible option for liver oligometastasis in breast cancers., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Japanese Radiation Research Society and Japanese Society for Radiation Oncology.)

Retardation of growth and development is a well-known late effect after radiotherapy for pediatric patients. The goal of the study was to examine the effect of proton beam therapy (PBT) on the growth of muscles included in the irradiated area. The subjects were 17 pediatric patients (age ≤ 5 years) who received PBT with a treatment field including a muscle on only one side out of a pair of symmetrical bilateral muscles and had imaging evaluations for at least 1 year after PBT. The thicknesses of the irradiated and non-irradiated (contralateral) muscles were measured retrospectively on CT or MRI axial images collected before and after PBT. The change of thickness divided by the period (years) for each muscle was compared between the irradiated and contralateral sides. Correlations of muscle growth with irradiation dose and age at the start of treatment were also evaluated. The median observation period was 39.2 months. The measurement sites included the erector spinae (n = 9), gluteus maximus (n = 5) and rhomboids + trapezius (n = 3) muscles. The average changes in muscle thickness were 0.24 mm/year on the irradiated side and 1.19 mm/year on the contralateral side, showing significantly reduced growth on the irradiated side (P = 0.001). Younger patients had greater muscle growth. Irradiation dose was not significant, but muscle growth tended to decrease as the dose increased, and muscles irradiated at >50 Gy (RBE) showed little growth. These results show that muscle growth is affected by PBT and that long-term follow-up is needed to evaluate muscle growth retardation., (© The Author(s) 2024. Published by Oxford University Press on behalf of The Japanese Radiation Research Society and Japanese Society for Radiation Oncology.)

Objective . In head-and-neck cancer intensity modulated proton therapy, adaptive radiotherapy is currently restricted to offline re-planning, mitigating the effect of slow changes in patient anatomies. Daily online adaptations can potentially improve dosimetry. Here, a new, fully automated online re-optimization strategy is presented. In a retrospective study, this online re-optimization approach was compared to our trigger-based offline re-planning (offline TB re-planning) schedule, including extensive robustness analyses. Approach . The online re-optimization method employs automated multi-criterial re-optimization, using robust optimization with 1 mm setup-robustness settings (in contrast to 3 mm for offline TB re-planning). Hard planning constraints and spot addition are used to enforce adequate target coverage, avoid prohibitively large maximum doses and minimize organ-at-risk doses. For 67 repeat-CTs from 15 patients, fraction doses of the two strategies were compared for the CTVs and organs-at-risk. Per repeat-CT, 10.000 fractions with different setup and range robustness settings were simulated using polynomial chaos expansion for fast and accurate dose calculations. Main results . For 14/67 repeat-CTs, offline TB re-planning resulted in <50% probability of D 98% ≥ 95% of the prescribed dose ( D pres ) in one or both CTVs, which never happened with online re-optimization. With offline TB re-planning, eight repeat-CTs had zero probability of obtaining D 98% ≥ 95% D pres for CTV 7000 , while the minimum probability with online re-optimization was 81%. Risks of xerostomia and dysphagia grade ≥ II were reduced by 3.5 ± 1.7 and 3.9 ± 2.8 percentage point [mean ± SD] ( p < 10 -5 for both). In online re-optimization, adjustment of spot configuration followed by spot-intensity re-optimization took 3.4 min on average. Significance . The fast online re-optimization strategy always prevented substantial losses of target coverage caused by day-to-day anatomical variations, as opposed to the clinical trigger-based offline re-planning schedule. On top of this, online re-optimization could be performed with smaller setup robustness settings, contributing to improved organs-at-risk sparing., (Creative Commons Attribution license.)

Background: We sought to characterize and compare late patient-reported outcomes (PROs) after moderately hypofractionated intensity modulated radiation therapy (IMRT) and proton beam therapy (PBT) for localized prostate cancer (PC)., Methods: This multi-institutional analysis included low- or intermediate-risk group PC patients treated with moderately hypofractionated radiation to an intact prostate stratified by treatment modality: IMRT or PBT. The primary outcomes were prospectively collected patient-reported late gastrointestinal (GI) and genitourinary (GU) toxicity assessed by International Prostate Symptom Score (IPSS) and Expanded PC Index Composite (EPIC). Multivariable regression analysis (MVA) controlling for age, race, and risk group tested the effect of time, treatment, and their interaction., Results: 287 IMRT and 485 PBT patients were included. Intermediate risk group (81.2 vs. 68.2%; p < 0.001) and median age at diagnosis (70 vs. 67 years; p < 0.001) were higher in the IMRT group. On MVA, there was no significant difference between modalities. PBT IPSS did not differ from IMRT IPSS at 12 months (odds ratio [OR], 1.19; p = 0.08) or 24 months (OR, 0.99; p = 0.94). PBT EPIC overall GI function at 12 months (OR, 3.68; p = 0.085) and 24 months (OR 2.78; p = 0.26) did not differ from IMRT EPIC overall GI function. At 24 months, urinary frequency was no different between PBT and IMRT groups (OR 0.35; p = 0.096)., Conclusions: This multi-institutional analysis of low- or intermediate-risk PC treated with moderately hypofractionated PBT and IMRT demonstrated low rates of late patient-reported GI and GU toxicities. After covariate adjustment, late GI and GU PROs were not significantly different between PBT or IMRT cohorts., (© 2023 Wiley Periodicals LLC.)

Purpose: Our purpose was to report the clinical and dosimetric attributes of patients with large unresectable hepatocellular carcinoma (HCC) undergoing proton or photon radiation therapy., Methods and Materials: We retrospectively analyzed the outcomes and dosimetric indices of 159 patients with >5 cm nonmetastatic HCC who underwent definitive radiation therapy using either protons (N = 105) or photons (N = 54) between 2014 and 2018. Additional photon plans were performed in the 105 proton-treated patients using the same dose prescription criteria for intragroup dosimetric comparison., Results: After a median follow-up of 47 months, patients with biologically effective dose (BED10) ≥ 75 Gy exhibited significantly better local control (LC; 2-year: 85.6% vs 20.5%; P < .001), progression-free survival (PFS; median, 7.4 vs 3.2 months; P < .001), and overall survival (OS; median, 18.1 vs 7.3 months; P < .001) compared with those with BED10 < 75 Gy. Notably, proton-treated patients had a significantly higher BED10 (96 vs 67 Gy; P < .001) and improved LC (2-year: 88.5% vs 33.8%; P < .001), PFS (median, 7.4 vs 3.3 months; P = .001), and OS (median, 18.9 vs 8.3 months; P < .001) than those undergoing photon radiation therapy. Furthermore, patients treated with protons had significantly lower V1 of the liver (P < .001), mean upper gastrointestinal tract dose (P < .001), and mean splenic dose (P < .001), with significantly decreased incidences of radiation-induced liver disease (P = .007), grade ≥3 upper gastrointestinal bleeding (P = .001), and grade ≥3 lymphopenia (P = .003). On multivariate analysis, proton radiation therapy consistently correlated with superior LC (P < .001), PFS (P < .001), and OS (P < .001). In intragroup dosimetric comparison, photon plans demonstrated significantly higher mean liver dose (P < .001) compared with actually delivered proton treatments, and 72 (69%) of them had mean liver dose exceeding 28 Gy, which necessitated target dose de-escalation., Conclusions: In the context of large HCC radiation therapy, a higher target BED10 was associated with improved outcomes. Notably, proton therapy has demonstrated the capability to deliver ablative doses while also being accompanied by fewer instances of severe toxicity., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Central nervous system (CNS) tumours account for around 25% of childhood neoplasms. With multi-modal therapy, 5-year survival is at around 75% in the UK. Conventional photon radiotherapy has made significant contributions to survival, but can be associated with long-term side effects. Proton beam radiotherapy (PBT) reduces the volume of irradiated tissue outside the tumour target volume which may potentially reduce toxicity. Our aim was to assess the effectiveness and safety of PBT and make recommendations for future research for this evolving treatment., Methods: A systematic review assessing the effects of PBT for treating CNS tumours in children/young adults was undertaken using methods recommended by Cochrane and reported using PRISMA guidelines. Any study design was included where clinical and toxicity outcomes were reported. Searches were to May 2021, with a narrative synthesis employed., Results: Thirty-one case series studies involving 1731 patients from 10 PBT centres were included. Eleven studies involved children with medulloblastoma / primitive neuroectodermal tumours (n = 712), five ependymoma (n = 398), four atypical teratoid/rhabdoid tumour (n = 72), six craniopharyngioma (n = 272), three low-grade gliomas (n = 233), one germ cell tumours (n = 22) and one pineoblastoma (n = 22). Clinical outcomes were the most frequently reported with overall survival values ranging from 100 to 28% depending on the tumour type. Endocrine outcomes were the most frequently reported toxicity outcomes with quality of life the least reported., Conclusions: This review highlights areas of uncertainty in this research area. A well-defined, well-funded research agenda is needed to best maximise the potential of PBT., Systematic Review Registration: PROSPERO-CRD42016036802., (© 2024. The Author(s).)

Purpose: A prospective multicenter registry study was started May 2016 in Japan to evaluate the efficacy and safety of proton beam therapy (PBT) for hepatocellular carcinoma (HCC)., Methods and Materials: Patients who received PBT for HCC from May 2016 to June 2018 were registered in the database of the Particle Beam Therapy Committee and Subcommittee of the Japanese Society for Radiation Oncology. Overall survival (OS), progression-free survival (PFS), and local recurrence were evaluated., Results: Of the 755 registered patients, 576 with initial PBT and no duplicate cancer were evaluated. At final follow-up, 322 patients were alive and 254 had died. The median follow-up period for survivors was 39 months (0-58 months). The median OS time of the 576 patients was 48.8 months (95% CI, 42.0-55.6 months) and the 1-, 2-, 3-, and 4-year OS rates were 83.8% (95% CI, 80.5%-86.6%), 68.5% (64.5%-72.2%), 58.2% (53.9%-62.2%), and 50.1% (44.9%-55.0%), respectively. Recurrence was observed in 332 patients, including local recurrence in 45 patients. The median PFS time was 14.7 months (95% CI, 12.4-17.0 months) and the 1-, 2-, 3-, and 4-year PFS rates were 55.2% (95% CI, 51.0%-59.2%), 37.5% (33.5%-41.5%), 30.2% (26.3%-34.2%), and 22.8% (18.5%-27.4%), respectively. The 1-, 2-, 3-, and 4-year OS rates were significantly higher for tumor size <5 versus 5 to 10 cm (P < .001) and <5 versus ≥10 cm (P < .001); Child-Pugh score A/B versus C (P < .001); and distance of the tumor from the gastrointestinal tract <1 versus 1 to 2 cm (P < .008) and <1 versus >2 cm (P < .001). At final follow-up, 27 patients (4.7%) had late adverse events of grade 3 or higher, with liver failure (n = 7), and dermatitis (n = 7) being most common., Conclusions: This multicenter prospective data registry indicated that PBT for HCC gives good therapeutic effects (3-year local control rate of 90%) with a low risk of severe late adverse events., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)