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Radiomics is a promising technique for discovering image based biomarkers of therapy response in cancer. Reproducibility of radiomics features is a known issue that is addressed by the image biomarker standardisation initiative (IBSI), but it remains challenging to interpret previously published radiomics signatures. This study investigates the reproducibility of radiomics features calculated with two widely used radiomics software packages (IBEX, MaZda) in comparison to an IBSI compliant software package (PyRadiomics). Intensity histogram, shape and textural features were extracted from 334 diffusion weighted magnetic resonance images of 59 head and neck cancer (HNC) patients from the PREDICT-HN observational radiotherapy study. Based on name and linear correlation, PyRadiomics shares 83 features with IBEX and 49 features with MaZda, a sub-set of well correlated features are considered reproducible (IBEX: 15 features, MaZda: 18 features). We explore the impact of including non-reproducible radiomics features in a HNC radiotherapy response model. It is possible to classify equivalent patient groups using radiomic features from either software, but only when restricting the model to reliable features using a correlation threshold method. This is relevant for clinical biomarker validation trials as it provides a framework to assess the reproducibility of reported radiomic signatures from existing trials.

Radiomics is a promising technique for discovering image based biomarkers of therapy response in cancer. Reproducibility of radiomics features is a known issue that is addressed by the image biomarker standardisation initiative (IBSI), but it remains challenging to interpret previously published radiomics signatures. This study investigates the reproducibility of radiomics features calculated with two widely used radiomics software packages (IBEX, MaZda) in comparison to an IBSI compliant software package (PyRadiomics). Intensity histogram, shape and textural features were extracted from 334 diffusion weighted magnetic resonance images of 59 head and neck cancer (HNC) patients from the PREDICT-HN observational radiotherapy study. Based on name and linear correlation, PyRadiomics shares 83 features with IBEX and 49 features with MaZda, a sub-set of well correlated features are considered reproducible (IBEX: 15 features, MaZda: 18 features). We explore the impact of including non-reproducible radiomics features in a HNC radiotherapy response model. It is possible to classify equivalent patient groups using radiomic features from either software, but only when restricting the model to reliable features using a correlation threshold method. This is relevant for clinical biomarker validation trials as it provides a framework to assess the reproducibility of reported radiomic signatures from existing trials.

Postoperative stereotactic radiosurgery after resection of brain metastases is currently the standard of care. However, rates of leptomeningeal disease (LMD) after postoperative stereotactic radiosurgery have been reported to be30%. Neoadjuvant stereotactic radiosurgery (NaSRS) has been proposed as an alternative treatment approach to decrease this risk.To report the local control (LC) and LMD rates in patients undergoing NaSRS.Our retrospective multicenter case series included consecutive patients planned for SRS followed by resection of intracranial lesions with a confirmed primary malignancy. Concurrent SRS alone to other intracranial lesions was permitted. Exclusion criteria included previous local treatment to that particular lesion and Eastern Cooperative Oncology Group performance status ≥3. Outcomes reported included LC, distant intracranial control (DC), overall survival, LMD, and radionecrosis (RN) rates.Overall, 28 patients with 29 lesions were eligible for analysis. The median follow-up was 12.8 months. The mean age was 62.5 (range 43-80) years, and 55% were Eastern Cooperative Oncology Group performance status 0 to 1. The most common primary malignancies included non-small cell lung cancer (43%) and melanoma (32%). Hypofractionated SRS was used in 62.1%. The 12-month LC and LMD rates were 91.3% and 4.0%, respectively. The 12-month RN, DC, and overall survival rates were 5.0%, 51.5%, and 60.1%, respectively.Compared with postoperative SRS, our study suggests that NaSRS leads to comparable local control with a decreased risk of LMD and RN. This is the first NaSRS series with a majority of patients treated with fractionated SRS. NaSRS is a promising approach for appropriate patients where surgical resection is a component of local therapy.

BACKGROUND Image-guided radiotherapy (IGRT) has significantly improved the precision in which radiotherapy is delivered in cancer treatment. Typically, IGRT uses bony landmarks and key anatomical structures to locate the tumor. Recent studies have demonstrated the feasibility of peri-tumor fiducials in enabling even more accurate delineation of target and normal tissue. The use of gold coils as fiducials in gastrointestinal tumors has been extensively studied. However, placement requires expertise and specialized endoscopic ultrasound equipment. This article reports the long-term outcomes of using a standard gastroscopy to inject liquid fiducials for the treatment of oesophageal and gastric tumors with IGRT. AIM To assess the long-term outcomes of liquid fiducial-guided IGRT in a cohort of oesophageal and gastric cancer patients. METHODS A retrospective cohort study of consecutive adults with Oesophagogastric cancers referred for liquid fiducial placement before definitive/neo-adjuvant or palliative IGRT between 2013 and 2021 at a tertiary hospital in Melbourne, Australia was conducted. Up to four liquid fiducials were inserted per patient, each injection consisting of 0.2-0.5mL of a 1:1 mixture of iodized oil (Lipiodol; Aspen Pharmacare) and n-butyl 2-cyanoacrylate (Histoacryl®; B. Braun). A 23-gauge injector (Cook Medical) was used for the injection. All procedures were performed by or under the supervision of a gastroenterologist. Liquid fiducial-based IGRT (LF-IGRT) consisted of computer-assisted direct matching of the fiducial region on cone-beam computerised tomography at the time of radiotherapy. Patients received standard-IGRT (S-IGRT) if fiducial visibility was insufficient, consisting of bone match as a surrogate for tumor position. Radiotherapy was delivered to 54Gy in 30 fractions for curative patients and up to 45Gy in 15 fractions for palliative treatments. RESULTS 52 patients were referred for liquid fiducial placement within the study period. A total of 51 patients underwent liquid fiducial implantation. Of these a total of 31 patients received radiotherapy. Among these, the median age was 77.4 years with a range between 57.5 and 88.8, and 64.5% were male. Twenty-seven out of the 31 patients were able to have LF-IGRT while four had S-IGRT. There were no complications after endoscopic implantation of liquid fiducials in our cohort. The cohort overall survival (OS) post-radiotherapy was 19 mo (range 0 to 87 mo). Whilst the progression-free survival (PFS) post-radiotherapy was 13 mo (range 0 to 74 mo). For those treated with curative intent, the median OS was 22.0 mo (range 0 to 87 mo) with a PFS median of 14.0 mo (range 0 to 74 mo). Grade 3 complication rate post-radiotherapy was 29%. CONCLUSION LF-IGRT is feasible in 87.1% of patients undergoing liquid fiducial placement through standard gastroscopy injection technique. Our cohort has an overall survival of 19 mo and PFS of 13 mo. Further studies are warranted to determine the long-term outcomes of liquid-fiducial based IGRT.

Second primary malignancy (SPM) may occur after index head and neck cancer (HNC) treatment. This study evaluated the prevalence and outcome of SPM in patients with HNC treated with definitive radiotherapy. Eligible patients include those with index mucosal HNC treated with definitive radiotherapy between 2000 and 2010. SPM was defined as an invasive cancer at a noncontiguous site diagnosed at least 6 months after completion of radiotherapy. Clinical data were collected, and the Kaplan–Meier method was used to estimate overall survival. In total, 1512 patients were studied. The majority of patients had index oropharyngeal cancer (86%). In all, 130 (9%) patients developed a SPM. The risk of SPM increased exponentially with time with 5-, 10-, and 15-year rates of 4, 10, and 25%. Half of SPMs were within the head and neck or thoracic regions. SPM rates were significantly higher (p

Introduction Extranodal follicular lymphoma (E-FL) is a rare entity that has distinct characteristics and outcomes compared with nodal follicular lymphoma. Patients and Methods This cohort comprised 37 patients with stages I/II E-FL, diagnosed from 2003 to 2013. Outcomes included progression-free survival (PFS), and overall survival (OS). Survival outcomes were calculated using Kaplan–Meier methods. Results Median age was 60 years (range, 37-84 years). Disease was stage I in 29 (78.4%). The Follicular Lymphoma International Prognostic Index score was 0 to 1 in 31 (83.8%), 2 in 2 (5.4%), 3 in 1 (2.7%), and missing in 3 (8.1%). Sites of involvement included the gastrointestinal (GI) tract in 22 (59.5%), and non-GI sites in 15 (40.5%). Initial management consisted of chemotherapy (CHT) alone in 21 (56.8%), radiation therapy (RT) alone in 2 patients (5.4%), RT and rituximab in 1 (2.7%), CHT and RT in 7 (18.9%), and observation in 6 (16.2%). RT was to a median dose of 30.6 Gy (range, 23.4-44.0 Gy). At a median follow-up of 69 months (range, 8-157 months), 5-year PFS and OS were 70.4% and 94.4%, respectively. Although the 5-year PFS of those observed was worse than for those who received therapy (33.3% vs. 77.6%; P = .011), that did not translate into an OS difference. Patients who received RT as part of upfront management had a 100% local control (LC) rate and a trend toward improved 5-year PFS (90% vs. 62.2%; P = .067). Conclusion Early stage E-FL is an indolent disease and is associated with excellent OS. Treatment strategies should be individualized with RT prioritized when LC is a significant goal.

Controversy exists regarding the optimal management of limited stage grade 3 follicular lymphoma (FL3). We assessed the treatment outcomes of 190 consecutive patients with stage I-II FL. Fifty two patients had FL3 disease, in whom the median age was 55 years. At a median follow-up of 65 months, 5-year progression-free survival (PFS) and overall survival (OS) rates were 76.6% and 87.6%, respectively. Patients receiving systemic therapy followed by radiation therapy (RT) had a significantly better PFS (

Background The current study was performed to assess the efficacy of surveillance imaging in patients with head and neck cancer (HNC) who are treated definitively with radiotherapy. Methods Eligible patients included those with a demonstrable disease-free interval (≥1 follow-up imaging procedure without evidence of disease and a subsequent visit/imaging procedure) who underwent treatment of HNC from 2000 through 2010. Results A total of 1508 patients were included. The median overall survival was 99 months, with a median imaging follow-up period of 59 months. Of the 1508 patients, 190 patients (12.6%) experienced disease recurrence (107 patients had locoregional and 83 had distant disease recurrence). A total of 119 patients (62.6%) in the group with disease recurrence were symptomatic and/or had an adverse clinical finding associated with the recurrence. Approximately 80% of patients with locoregional disease recurrences presented with a clinical finding, whereas 60% of distant disease recurrences were detected by imaging in asymptomatic patients. Despite the earlier detection of disease recurrence via imaging, those patients in the group of patients with clinically detected disease recurrence were significantly more likely to undergo salvage therapy compared with those whose recurrence was detected on imaging (odds ratio, 0.35). There was no difference in overall survival noted between those patients with disease recurrences that were detected clinically or with imaging alone. Approximately 70% of disease recurrences occurred within the first 2 years. In those patients who developed disease recurrence after 2 years, the median time to recurrence was 51 months. After 2 years, the average number of imaging procedures per patient for the detection of a salvageable recurrence for the imaging-detected group was 1539. Conclusions Surveillance imaging in asymptomatic patients with HNC who are treated definitively with radiotherapy without clinically suspicious findings beyond 2 years has a low yield and a high cost. Physicians ordering these studies must use judicious consideration and discretion.

BACKGROUND: The objective of the current study was to characterize the incidence, pattern, and impact on oncologic outcomes of retropharyngeal lymph node (RPLN) involvement in HPV-associated oropharyngeal cancer (OPC). METHODS: Data regarding patients with HPV-associated OPC who were treated at The University of Texas MD Anderson Cancer Center with intensity-modulated radiotherapy from 2004 through 2013 were analyzed retrospectively. RPLN status was determined by reviewing pretreatment imaging and/or reports. Outcomes analysis was restricted to patients with lymph node-positive (+) disease. Kaplan-Meier survival estimates were generated and survival curves were compared using the log-rank test. Bayesian information criterion assessed model performance changes with the addition of RPLN status to current American Joint Committee on Cancer staging. Competing risk analysis compared modes of disease recurrence. RESULTS: The incidence of radiographic RPLN involvement was 9% (73 of 796 patients) and was found to vary by primary tumor site. The 5-year rates of freedom from distant metastases (FDM) and overall survival were lower in patients with RPLN(+) status compared with those with RPLN-negative (−) status (84% vs 93% [P = .0327] and 74% vs 87% [P = .0078], respectively). RPLN(+) status was not found to be associated with outcomes on multivariate analysis. Bayesian information criterion analysis demonstrated that current American Joint Committee on Cancer staging was not improved with the inclusion of RPLN. Locoregional and distant disease recurrence probabilities for those patients with RPLN(+) status were 8% and 13%, respectively, compared with 10% and 6%, respectively, for those with RPLN(−) status. RPLN(+) status portended worse 5-year FDM in the low-risk subgroup (smoking history of

Objectives To implement a system for unsupervised extraction of tumor stage and prognostic data in patients with genitourinary cancers using clinicopathological and radiology text. Methods A corpus of 1054 electronic notes (clinician notes, radiology reports and pathology reports) was annotated for tumor stage, prostate specific antigen (PSA) and Gleason grade. Annotations from five clinicians were reconciled to form a gold standard dataset. A training dataset of 386 documents was sequestered. The Medtex algorithm was adapted using the training dataset. Results Adapted Medtex equaled or exceeded human performance in most annotations, except for implicit M stage (F-measure of 0.69 vs 0.84) and PSA (0.92 vs 0.96). Overall Medtex performed with an F-measure of 0.86 compared to human annotations of 0.92. There was significant inter-observer variability when comparing human annotators to the gold standard. Conclusions The Medtex algorithm performed similarly to human annotators for extracting stage and prognostic data from varied clinical texts.

Highlights • Unilateral radiotherapy is utilised in T1-2, N0-N1 lateralised tonsillar tumours. • The role of unilateral radiotherapy in more advanced nodal disease is less clear. • Higher symptom burden and lower QoL was reported by patients treated with bilateral radiotherapy. • In the IMRT era, bilateral treatment for tonsillar cancer may have an enduring impact on the patient. • Prospective evaluation of unilateral radiotherapy with lateralised tumours and N2-3 is needed., Purpose The purpose of this study was to compare self-reported health-related quality of life (QoL) and symptom burden in early stage tonsillar carcinoma patients treated with unilateral (URT) and bilateral radiotherapy (BRT). Methods and materials This is a secondary analysis of a larger study assessing patient reported outcomes in human papillomavirus (HPV) oropharyngeal cancer (OPC) patients. Recruited patients were ≥12 months from completion of radiotherapy. This analysis included only patients with T1-2, N1-2b tonsil cancer and excluded patients with base of tongue involvement or recurrent disease. QoL and patient reported toxicity was measured using the EORTC QLQ-C30 module and the MDASI-HN. Results Patients were enrolled from November 2018 to May 2019. Of the 136 patients recruited to the main study, 43 were eligible for this substudy (22 URT, 21 BRT), with a median age and follow up of 58.2 and 3.0 years respectively. The two groups were balanced with respect to patient, tumor and treatment factors with the exception of higher rates of T2 disease (27% v 71%, p = 0.006) and more extensive GTV nodal volumes (11.0 v 25.5cc, p = 0.006) in the BRT group. BRT patients had lower global health status/QoL (84 v 69, p = 0.0005) and social functioning scores (93 vs 78, p = 0.033) on the EORTC QLQ-C30, and higher symptom severity (0.6 vs. 2.0, p = 0.001) and symptom interference scores (0.8 vs. 2.0, p = 0.010) on the MDASI-HN. Four of the six largest differences observed on MDASI-HN items were attributable to radiotherapy technique (dry mouth, mucous, difficulty swallowing/chewing and taste), with corresponding dose differences to the respective organs (contralateral parotid, oral cavity and pharyngeal constrictors). In every instance, severity of symptoms was worse on average for patients treated with BRT. Conclusions In the highly conformal radiotherapy era, BRT in early HPV tonsillar cancer survivors has an enduring impact on long-term QoL and toxicity.

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Head and neck squamous cell carcinoma (HNSCC) treatment response relies heavily on macroscopic clinical findings. Blood monitoring of circulating markers during treatment may improve earlier detection of responders versus non-responders during radiotherapy. In this study, patients with intact tumour of HNSCC were enrolled in the prospective PREDICT-HN study. Pre-, after first treatment, weekly, and post-treatment blood samples were collected. CTC was enumerated using the CellSearch system. cfDNA was quantified from cfNA isolated at pre-, mid- and post-treatment timepoints. Blood samples were collected from 45 patients. Of the 339 samples analysed for CTC, 31% had detectable CTCs. Nine patients had detectable CTCs (1-3/7.5ml blood) in pre-treatment samples. After 1 fraction, 16 patients had CTCs detected, with 12 who had no pre-treatment CTC. Sixteen (36%) patients had detectable CTC in final week of treatment. There was no correlation between cancer stage, nodal status and tumour burden with CTC. cfDNA levels increased during treatment, with its highest level in the final week and lowest at post-treatment. Our results showed in HNSCC that CTCs can be detected during radiotherapy, suggesting mobilization into circulation during treatment, with as-yet-unknown viability. cfDNA kinetics during treatment correlated with CTC release, and may indicate apoptotic change.Simple SummaryHead and neck squamous cell carcinoma (HNSCC) treatment response relies heavily on macroscopic clinical findings. Blood monitoring of circulating markers such as circulating tumour cell (CTC) and cell-free DNA (cfDNA) during treatment may improve earlier detection of responders versus non-responders during definitive radiotherapy. Although the detection of CTCs and cfDNA in patients with HNSCC has been described, there is minimal data on the kinetics of CTC counts and cfDNA levels during radiotherapy in patients with HNSCC. Here, our study prospectively describes the changes in CTC and cfDNA enumeration during radiotherapy in patients with HNSCC. Our results showed, for the first time to our knowledge, in HNSCC, that CTCs can be detected during radiotherapy, suggesting mobilization into peripheral circulation during treatment, with as-yet-unknown viability. cfDNA kinetics during treatment correlated with CTC release, may indicate apoptotic change during radiotherapy. Combined cfDNA-CTC as an early marker of treatment response should be investigated further.

Osteoradionecrosis (ORN) is a major side-effect of radiation therapy in oropharyngeal cancer (OPC) patients. In this study, we demonstrate that early prediction of ORN is possible by analyzing the temporal evolution of mandibular subvolumes receiving radiation. For our analysis, we use computed tomography (CT) scans from 21 OPC patients treated with Intensity Modulated Radiation Therapy (IMRT) with subsequent radiographically-proven ≥ grade II ORN, at three different time points: pre-IMRT, 2-months, and 6-months post-IMRT. For each patient, radiomic features were extracted from a mandibular subvolume that developed ORN and a control subvolume that received the same dose but did not develop ORN. We used a Multivariate Functional Principal Component Analysis (MFPCA) approach to characterize the temporal trajectories of these features. The proposed MFPCA model performs the best at classifying ORN vs Control subvolumes with an area under curve (AUC) = 0.74 (95% confidence interval (C.I.): 0.61-0.90), significantly outperforming existing approaches such as a pre-IMRT features model or a delta model based on changes at intermediate time points, i.e. at 2- and 6-month follow-up. This suggests that temporal trajectories of radiomics features derived from sequential pre- and post-RT CT scans can provide markers that are correlates of RT-induced mandibular injury, and consequently aid in earlier management of ORN.

Head and neck squamous cell carcinoma (HNSCC) is a deadly disease which in many cases is managed with a combination of radiation and chemotherapy. Unfortunately, the ability to monitor treatment response in real time is limited. Thus, truly individualized therapy remains an unrealized goal. We have previously investigated the possibility of combining advanced imaging using magnetic resonance imaging (MRI) combined with the analysis of circulating tumor cells to classify response in HNSCC as part of a prospective trial (PREDICT-HN). An adaption of the methodology from that trial is described herein in hopes of allowing for recapitulation and further development of this exciting methodology.

Head and neck squamous cell carcinoma (HNSCC) is a deadly disease which in many cases is managed with a combination of radiation and chemotherapy. Unfortunately, the ability to monitor treatment response in real time is limited. Thus, truly individualized therapy remains an unrealized goal. We have previously investigated the possibility of combining advanced imaging using magnetic resonance imaging (MRI) combined with the analysis of circulating tumor cells to classify response in HNSCC as part of a prospective trial (PREDICT-HN). An adaption of the methodology from that trial is described herein in hopes of allowing for recapitulation and further development of this exciting methodology.

In many applications based on kinetic evaluation analysis and model fitting, quantitative mapping retrieved on data series from modalites such as MRI is completed on a voxel-by-voxel basis, where motion and low signal to noise ratio (SNR) would considerably degenerate the reliability of estimations. The coherence of image series in space and time can be used as prior knowledge to mitigate this occurrence. In this study, spatial and temporal higher-order total variations (HOTVs) are applied on a data series of MRI signal (e.g. dynamic contrast-enhanced (DCE) MRI and intravoxel incoherent motion (IVIM) MRI) to exploit the coherence of signal in space and time to minimize the variabilities caused by motion as well as improving quality of images with low SNR while retaining the physical details of original data properly. Simultaneously applying spatial and temporal HOTVs on images is non-trivial in implementation since it is a non-smooth optimization problem with multiple regularizers. Therefore, we use the proximal gradient method as well as a primal-dual split proximal mechanism to address the problem properly. In addition to increase the reliability of quantitative parametric map estimations, this preprocessing procedure can be included into many existing map estimation algorithms and pipelines effortlessly. We demonstrate our method on the parametric maps estimation for DCE MRI and IVIM MRI.

Background and purpose The chemotherapy exposure during chemoradiotherapy for rectal cancer is adequate for radiosensitization but suboptimal for treatment of distant micrometastasis. This study aimed to determine tolerability, dose intensity, response, and toxicity of a novel intensified neoadjuvant treatment approach. Materials and Methods Eligible patients were MRI-staged T3-4NxM0 rectal adenocarcinoma. Treatment consisted of FOLFOX chemotherapy given in weeks 1, 6, and 11 with pelvic radiotherapy (25.2 Gy in 3 weeks in 1.8 Gy/fraction with oxaliplatin and 5-FU continuous infusion) given in weeks 3–5, and weeks 8–10. Surgery was performed 4–6 weeks later. The primary endpoint was tolerability defined as the percentage of patients who were able to complete the planned treatment course. Survival rates were estimated using the Kaplan-Meier method. Results Median age of the 40 patients was 61.5 years. Rectal MRI-stage was T3 in 88%. Overall, 95% completed the regimen. All patients received 50.4 Gy. Relative dose intensity (≥75%) was 92% and 98% for oxaliplatin and 5-FU, respectively. High grade toxicities included neutropenia (25% grade 3; 7.5% grade 4) and diarrhoea (10%). Pathologic CR rate was 20%. Median follow-up was 54 months. The 5-year overall survival, freedom from relapse, locoregional control, and freedom from distant metastasis of the cohort was 82%, 72%, 97% and 72%. Conclusions Delivery of intensified neoadjuvant treatment with interdigitating chemotherapy and radiotherapy is feasible with no increase in acute perioperative complications. A larger prospective study is required to further evaluate the potential survival benefit of this design.

PurposeTo describe the baseline and serial tumor microbiome in HPV-associated oropharynx cancer (OPC) over the course of radiotherapy (RT).MethodsPatients with newly diagnosed HPV-associated OPC treated with definitive radiotherapy +/- concurrent chemotherapy were enrolled in this prospective study. Using 16S rRNA gene sequencing, dynamic changes in tumor microbiome during RT were investigated. Surface tumor samples were obtained before RT and at week 1, 3 and 5 of RT. Radiological primary tumor response at mid-treatment was categorized as complete (CR) or partial (PR).ResultsTen patients were enrolled. Mean age was 63 years (range: 51-71). As per AJCC 8th Ed, 50%, 20% and 30% of patients had stage I, II and III, respectively. At 4-weeks, 7 patients had CR and 3 patients had PR; at follow-up imaging post treatment, all patients had CR. Baseline diversity of tumoral and buccal microbiomes was not statistically different. For the entire cohort, alpha diversity was significantly decreased over the course of treatment (p=0.02). There was a significant alteration in the bacterial community within the first week of radiation. Baseline tumor alpha diversity of patients with CR was significantly higher than those with PR (p=0.03). While patients with CR had significant reduction in diversity over the course of radiation (p=0.02), the diversity remained unchanged in patients with PR. Patients with history of smoking had significantly increased abundance of Granulicatella (p=0.04), and Kingella (0.05) and lower abundance of Alloprevotella (p=0.04) compared to never smokers.ConclusionsThe tumor microbiome of HPV-associated OPC exhibits reduced alpha diversity and altered taxa abundance over the course of radiotherapy. The baseline bacterial profiles of smokers vs. non-smokers were inherently different. Baseline tumor alpha diversity of patients with CR was higher than patients with PR, suggesting that the microbiome as a biomarker of radiation response deserves further investigation.

Purpose/Objective Radiation-induced lymphopenia has been associated with poor survival outcomes in certain solid tumors such as esophageal, lung, cervical and pancreatic cancers. We aim to determine the effect of treatment-related lymphopenia during radiotherapy on outcomes of patients with oropharyngeal cancer. Materials/Methods A retrospective analysis of all patients who completed definitive radiotherapy for oropharyngeal cancer at The University of Texas MD Anderson Cancer Center and had blood counts taken during radiotherapy from 2002 to 2013 were included. Patient, tumor and treatment characteristics, clinical outcomes and lymphocyte counts during radiotherapy were recorded. Lymphopenia was graded according to the CTCAE v4.0. Survival rates were estimated using the Kaplan-Meier method and compared with log-rank tests. Results 850 patients were evaluated. The median age was 57 years. The majority of the cohort had p16/HPV-positive disease (71%), 8% had HPV-negative disease and 21% were unknown. The median radiation total dose was 70 Gy. 45% of patients had induction chemotherapy, and 87% had concurrent chemotherapy. 703 (83%) patients developed ≥grade 3 (G3) lymphopenia and 209 (25%) had grade 4 (G4) lymphopenia during radiotherapy. The median follow-up was 59 months; the 5-year overall survival rate was 81%. There were no significant differences in overall survival rates nor in disease control rates, in those who developed G3/G4 lymphopenia compared with those who did not. No significant effect of lymphopenia on survival was observed when analyzed according to p16/HPV status. Conclusion In this large cohort of patients with oropharyngeal cancer, the development of lymphopenia during radiotherapy did not impact outcomes.

Purpose Patients with p16/human papilloma virus (HPV)–associated oropharyngeal squamous cell carcinoma have a favorable outcome after treatment. In this group of patients who could have a long life expectancy, the optimal surveillance strategy and modality is not well established. We aim to determine the ability of a negative postradiation positron emission tomography (PET)/computed tomography scan to predict the risk of subsequent relapse in these patients. Materials and Methods A retrospective analysis of patients with p16/HPV-associated oropharyngeal squamous cell carcinoma who completed definitive (chemo)radiation therapy and had a posttreatment PET/computed tomography scan from 2006 to 2013 was performed. Patient, tumor, and treatment characteristics and clinical outcomes were recorded. Tumors were considered HPV/p16 positive if either HPV (by in situ hybridization) or p16 (by immunohistochemistry) was positive. Disease-free survival and overall survival rates were estimated using the Kaplan-Meier method. Results In our study, 327 patients were evaluated. The median age was 57 years. The most common primary sites were base of tongue (50%) and tonsil (48%). Of the patients evaluated, 291 (89%) had a negative posttreatment PET scan. For these 291 patients who had a complete metabolic response after treatment, the 5-year disease-free survival and overall survival rates were 91% and 89%, respectively. The median time to development of recurrence was 16 months. Of the 291 patients, 24 patients (8%) had disease recurrence; 13 recurrences were locoregional, and 13 were distant. Eleven (4%) patients with recurrence had further surgery or radiation, and 8 patients (3%) were without disease as of the last follow-up. Conclusions Patients who achieve a complete metabolic response on posttreatment PET imaging have an excellent prognosis, and the risk of developing a recurrence in the future is very low. Therefore, a more cost effective surveillance program should be considered for this subgroup of patients.

Highlights • Treatment de-escalation in HPV+ oropharynx cancer is an active area of research. • A Bayesian phase II trial of MR-guided radiotherapy dose adaptation is proposed. • High dose volume will be adapted on weekly MRI based on tumor response. • The non-inferiority of dose adaptation compared to standard IMRT will be assessed., Background Current standard radiotherapy for oropharynx cancer (OPC) is associated with high rates of severe toxicities, shown to adversely impact patients’ quality of life. Given excellent outcomes of human papilloma virus (HPV)-associated OPC and long-term survival of these typically young patients, treatment de-intensification aimed at improving survivorship while maintaining excellent disease control is now a central concern. The recent implementation of magnetic resonance image – guided radiotherapy (MRgRT) systems allows for individual tumor response assessment during treatment and offers possibility of personalized dose-reduction. In this 2-stage Bayesian phase II study, we propose to examine weekly radiotherapy dose-adaptation based on magnetic resonance imaging (MRI) evaluated tumor response. Individual patient’s plan will be designed to optimize dose reduction to organs at risk and minimize locoregional failure probability based on serial MRI during RT. Our primary aim is to assess the non-inferiority of MRgRT dose adaptation for patients with low risk HPV-associated OPC compared to historical control, as measured by Bayesian posterior probability of locoregional control (LRC). Methods Patients with T1-2 N0-2b (as per AJCC 7th Edition) HPV-positive OPC, with lymph node

Key Clinical Message This study highlights gamma knife stereotactic radiosurgery (GK‐SRS) as boost therapy in a patient with adenoid cystic carcinoma of the parotid involving the skull base and invasion of the facial nerve. Using GK‐SRS, dose to the brainstem and temporal lobe were reduced when compared to less conformal radiotherapy techniques.

Basal cell carcinoma accounts for up to 80% of all non-melanoma skin cancers and is the most common cancer in the world. The primary aim of treatment for basal cell carcinomas is local control, as regional and distant spread is very rare. Although surgery remains the preferred modality for definitive treatment at most centers, radiotherapy is frequently considered for those patients who are medically inoperable and who have unresectable tumors or for those who decline surgery. Other relative indications for radiotherapy include cases where it would be difficult to achieve clear surgical margins and where surgery would result in unacceptable functional or cosmetic morbidity.

To evaluate the impact of positron emission tomography (PET) staging on overall survival (OS) and progression-free survival (PFS) in patients with early-stage (stages I and II) follicular lymphoma (ESFL) treated with radiation therapy alone. Eighty-five patients with ESFL treated with curative-intent radiation therapy (RT) between December 2000 and May 2011 were identified. Of those, 13 who had no PET staging and 25 who received additional systemic therapy were excluded from the analysis. Thus, we analyzed 47 patients with PET-staged ESFL treated with definitive radiation therapy alone (dose > 23Gy). Tumour features, pre-treatment computed tomography (CT) and PET stage, dose fractionation, and radiation therapy field extent were recorded. The Kaplan–Meier method was used to estimate the OS and PFS. Patterns of failure were assessed as cumulative incidences assuming competing risks. Median age was 57 years (range 24–83); 43% were females. Most were PET stage 1 (76.6%). Median maximum nodal diameter was 3 cm. Median pre-treatment lactate dehydrogenase (LDH) was 327.5 (range 123–607, upper normal limit = 220). Twenty-six patients (55.3%) had infra-diaphragmatic disease. All received 30–36Gy in 15–24 fractions, with 59.6% treated with involved-field radiation therapy (IFRT) techniques. There was no significant difference in PFS between CT stage I and stage II (HR 1.30 95% CI [0.25–6.72], p = 0.75) with a 5-year PFS of 77% and 78% respectively. However, stage I on PET staging had a significantly better PFS than stage II (HR 4.66 95% CI [1.15–18.8], p = 0.038), with 5-year PFS of 84% and 60% respectively. Ten patients had recurrent disease, with distant disease being the first site of failure in seven patients. Seven-year OS was 91% (95% CI 79–100) for the whole cohort. FDG-PET should be considered an essential element in the evaluation of patients with ESFL being considered for RT.

Background There are few published studies to guide the treatment of carcinoma metastatic to the neck from an unknown primary (CUP). In this regard, the objective of the current study was to share the authors' current experience treating patients with CUP using intensity-modulated radiation therapy (IMRT), which principally targeted both sides of the neck, the nasopharynx, and the oropharynx. Methods This was a retrospective study in which an institutional database search was conducted to identify patients with CUP who received IMRT. Data analysis included frequency tabulation, survival analysis, and multivariable analysis. Results Two-hundred sixty patients met inclusion criteria. The most common lymph node category was N2b (54%). IMRT volumes included the entire pharyngolaryngeal mucosa in 78 patients, the nasopharynx and oropharynx in 167 patients, and treatment limited to the involved neck in 11 patients. Eighty-four patients underwent neck dissections. The 5-year overall survival, regional control, and distant metastases-free survival rates were 84%, 91%, and 94%, respectively. Over 40% of patients had gastrostomy tubes during therapy, and 7% patients were diagnosed with chronic radiation-associated dysphagia. Higher lymph node burden was associated with worse disease-related outcomes, and in subgroup analysis, patients with human papillomavirus-associated disease had better outcomes. No therapeutic modality was statistically associated with either disease-related outcomes or toxicity. Conclusions Comprehensive IMRT with treatment to both sides of the neck and to the oropharyngeal and nasopharyngeal mucosa results in high rates of disease control and survival. The investigators were unable to demonstrate that treatment intensification with chemotherapy or surgery added benefit or excessive toxicity. Cancer 2018;124:1415-27. © 2018 American Cancer Society.

The FIG study is a prospective non-randomised study now recruiting up to 210 newly diagnosed GBM participants across ten Australian sites. Study outcomes will address the role of [18F] fluoroethyl-L-tyrosine positron emission tomography (FET-PET) in radiotherapy (RT) planning, evaluation of post-treatment changes versus disease progression and prognostication. We describe here the methodology and preliminary outcomes for site credentialing. Eligible participants with GBM undergo FET-PET imaging at three time-points: FET-PET1-post-operative pre-chemo-RT, FET-PET2 acquired one month post-chemo-RT and FET-PET3 (+/-FDG-PET) triggered when clinical and/or radiological (MRI) progression is suspected. Dynamic and static FET-PET images are analysed qualitatively and quantitatively. Radiotherapy is as per standard care with the treating Radiation Oncologist (RO) blinded to FET-PET1. Site nuclear medicine (NM) physicians are required to delineate a biological target volume (BTV) based on FET-PET1 with hybrid RT volumes derived post-hoc. Pre-trial NM quality assurance comprises certification from the Australasian Radiopharmaceutical Trials Network encompassing FET-PET radiochemistry Quality Control and PET camera calibration. Site and central integrated workflows incorporating multi-modality image registration, target volume/region of interest contouring and analysis have been developed. NM benchmarking involves delineation of FET-PET BTVs in 3 cases with another 3 cases addressing response criteria interpretation harmonized across FET-PET, FDG-PET and MRI. Site ROs complete 3 cases involving standard and hybrid target volume delineation based on pre-derived FET-PET volumes. All NM and RO credentialing cases undergo central expert review. To date, of six sites which have submitted full credentialing data, 19/21 RO and 6/6 planning cases were passed. Of 72 NM cases, 18/72 (25%) required resubmission, primarily related to ensuring standardisation of background regions and time activity curve interpretation. The FIG study will be pivotal in establishing the role of FET-PET in GBM management. The robust NM and RO credentialing program will build capacity and expertise in FET-PET production, acquisition and image interpretation.

Purpose/Objective(s) In the setting of head and neck (HN) re-irradiation (reRT), the goal is to adequately cover disease with as small a volume as appropriate to minimize normal tissue toxicity without compromising local control. However, it can be a challenge to gauge the extent microscopic disease beyond the gross tumor to be included in the reRT volume. Here, we aim to determine the patterns of failure after HN reRT. Materials/Methods Patients treated with curative intent intensity modulated radiation therapy (IMRT) or proton reRT from September 1999 – June 2015 were evaluated. A total of 148 patients with inoperable tumors received definitive reRT (intact) and 61 who underwent salvage surgery received post-operative reRT (postop). Those who had locoregional recurrence (LRR) and intact imaging data were analyzed. Using deformable imaging registration, diagnostic images at time of recurrence were overlaid on reRT treatment plans. The site of recurrence was delineated and evaluated by at least 2 radiation oncologists/radiologist with HN expertise. The patterns of failure were classified into five types based on spatial and dosimetric criteria: A (central high dose, or “in-field”), B (peripheral high dose), C (central elective dose), D (peripheral elective dose), and E (extraneous dose, or “out-of-field”). For patients who had multiple sites of recurrences, each site was classified independently. The kappa statistic was used to assess the inter-observer agreement on failure classification. Results Of the 209 patients treated, 67 developed LRR. This represented 44 of 148 (30%) intact patients (median dose 66 Gy) and 23 of 61 (38%) postop patients (median dose 60 Gy). Of these, 41 (61%) had imaging data for analysis, representing 47 sites of failures. Median time to failure was 21 weeks (range: 4 – 220 weeks). Patterns of failure among intact reRT were as follows: 13 Type A (39%), 6 Type B (18%), 1 Type C (3%), and 13 Type E (39%). The majority (79%) of failures were either in the high dose field or completely out of field. Interobserver agreement was 0.92. Patterns of failure among postop reRT were as follows: 4 type A (17%), 5 type B (22%), 5 type C (22%) and 5 type D (22%). The majority (56%) of recurrences were within 1 cm of the reconstructive flap bed, 40% recurred in the same primary subsite, and 17% recurred in the 1st echelon nodal level. Interobserver agreement was 0.68. Conclusion In patients who recurred after reRT, the majority was either within the central high-dose region, or completely outside the high-dose region suggesting poor disease biology. Biologic dose-escalation and or the addition of systemic therapies may offer improved disease control.

Background The purpose of this study was to present our experience with retropharyngeal node reirradiation using highly conformal radiotherapy (RT). Methods A retrospective screen of 2504 consecutively irradiated patients with head and neck malignancies between 2005 and 2015 identified 19 patients who underwent reirradiation for retropharyngeal node metastasis. Clinical and toxicity outcomes were assessed in these patients. Results Thirteen patients (68%) had squamous cell carcinoma. Eleven patients (58%) received conventionally fractionated intensity-modulated radiotherapy (IMRT) or proton therapy, and 8 patients (42%) received single-fractionated or hypofractionated stereotactic RT. Fourteen patients (74%) received chemotherapy. Median follow-up was 14.7 months. The 1-year local control, locoregional control, overall survival, and progression-free survival rates were 100%, 94%, 92%, and 92%, respectively. Three patients (16%) experienced acute grade 3 toxicity and occurred in those treated with IMRT. There was no late grade ≥3 toxicity. Conclusion Retropharyngeal node reirradiation with conformal therapy is well tolerated and associated with excellent short-term disease control.

Background: Prostate cancer management involves a balance between the risks of cancer death against those from other causes. To evaluate the performance of several comorbidity indices in predicting comorbid death in a prostate cancer radiotherapy cohort. Methods: 2,131 men with localised prostate cancer treated with radical radiotherapy between 1999 and 2007 were studied. Tumour features, androgen deprivation usage, age, number of prescription medications (PMN) and Adult Comorbidity Evaluation-27 Index (ACE-27) were recorded. Death from prostate cancer (DPC) and death from other causes (DOC) were analysed as competing causes of death using a competing risks model, with discrimination assessed using the concordance index. Results: ACE-27 scores correlated with patient’s PMN (median PMN = 2). Tumour features were independent of ACE-27 scores. Estimated cumulative incidences of DOC and DPC at 10 years were 16.4% and 7.7% respectively. In the low/intermediate risk group (n = 1026) there was a 3.4-fold predominance of DOC inside 10 years (cumulative incidence: 15.8% DOC vs 3.4% DPC). High-risk men had approximately equal rates of DPC and DOC at 10 years. Multivariable analysis showed age, ACE-27 score ≥ 1 and PMN to have significant associations with DOC (P

Purpose We evaluated the geometric and dosimetric-based distribution of mucosal and nodal recurrences in patients with metastatic head and neck squamous cell carcinoma to cervical lymph nodes of unknown primary after intensity modulated radiation therapy using validated typology-indicative taxonomy. Methods and Materials We reviewed the data of 260 patients who were irradiated between 2000 and 2015 and had a median follow-up time for surviving patients of 61 months. The mucosal and nodal recurrences were manually delineated on computed tomography images demonstrating the recurrences. The images were overlaid on the treatment plan using deformable image registration. The locations of the recurrences were determined relative to the original planning target volumes and doses using centroid-based approaches. Subsequently, the pattern of failures were classified into 5 types based on combined spatial and dosimetric criteria: A (central high dose), B (peripheral high dose), C (central elective dose), D (peripheral elective dose), and E (extraneous dose). For patients with type A failure with simultaneous nontype A lesions, the overall pattern of failures was defined as type A. Results Thirty-two patients had mucosal or nodal recurrences. The most common clinical nodal stage was N2b (66%). Preradiation therapy neck dissections were performed in 6 patients. The median dose delivered to clinical tumor volume 1 was 66 Gy. The majority (84%) had total/partial pharyngeal mucosa elective irradiation. Twenty-three patients had nodal recurrences, 8 had mucosal recurrences, and 1 had both nodal and mucosal recurrences. Twenty-one patients (91%) had type A nodal failure, and 7 of the mucosal failures (89%) were type C. Conclusions The majority of nodal recurrences occurred within the high-dose area, demanding the need for identification of radioresistant areas within malignant nodes. Future studies should focus on either dose escalation of high-risk volumes or novel radiosensitizers.

Purpose The use of magnetic resonance imaging (MRI) in radiotherapy treatment planning has rapidly increased due to its ability to evaluate patient's anatomy without the use of ionizing radiation and due to its high soft tissue contrast. For these reasons, MRI has become the modality of choice for longitudinal and adaptive treatment studies. Automatic segmentation could offer many benefits for these studies. In this work, we describe a T2-weighted MRI dataset of head and neck cancer patients that can be used to evaluate the accuracy of head and neck normal tissue auto-segmentation systems through comparisons to available expert manual segmentations. Acquisition and validation methods T2-weighted MRI images were acquired for 55 head and neck cancer patients. These scans were collected after radiotherapy computed tomography (CT) simulation scans using a thermoplastic mask to replicate patient treatment position. All scans were acquired on a single 1.5 T Siemens MAGNETOM Aera MRI with two large four-channel flex phased-array coils. The scans covered the region encompassing the nasopharynx region cranially and supraclavicular lymph node region caudally, when possible, in the superior-inferior direction. Manual contours were created for the left/right submandibular gland, left/right parotids, left/right lymph node level II, and left/right lymph node level III. These contours underwent quality assurance to ensure adherence to predefined guidelines, and were corrected if edits were necessary. Data format and usage notes The T2-weighted images and RTSTRUCT files are available in DICOM format. The regions of interest are named based on AAPM's Task Group 263 nomenclature recommendations (Glnd_Submand_L, Glnd_Submand_R, LN_Neck_II_L, Parotid_L, Parotid_R, LN_Neck_II_R, LN_Neck_III_L, LN_Neck_III_R). This dataset is available on The Cancer Imaging Archive (TCIA) by the National Cancer Institute under the collection "AAPM RT-MAC Grand Challenge 2019" (https://doi.org/10.7937/tcia.2019.bcfjqfqb). Potential applications This dataset provides head and neck patient MRI scans to evaluate auto-segmentation systems on T2-weighted images. Additional anatomies could be provided at a later time to enhance the existing library of contours.

BACKGROUND A possible surveillance model for patients with head and neck cancer (HNC) who received definitive radiotherapy was created using a partially observed Markov decision process. The goal of this model is to guide surveillance imaging policies after definitive radiotherapy. METHODS The partially observed Markov decision process model was formulated to determine the optimal times to scan patients. Transition probabilities were computed using a data set of 1508 patients with HNC who received definitive radiotherapy between the years 2000 and 2010. Kernel density estimation was used to smooth the sample distributions. The reward function was derived using cost estimates from the literature. Additional model parameters were estimated using either data from the literature or clinical expertise. RESULTS When considering all forms of relapse, the model showed that the optimal time between scans was longer than the time intervals used in the institutional guidelines. The optimal policy dictates that there should be less time between surveillance scans immediately after treatment compared with years after treatment. Comparable results also held when only locoregional relapses were considered as relapse events in the model. Simulation results for the inclusive relapse cases showed that

Purpose Active Breathing Coordinator (Elekta AB, Crawley, UK) is a motion management strategy for radiation treatment. During setup, aligning the patient to the bony spine alone does not necessarily lead to an accurate alignment to soft tissue targets, and further adjustment is necessary. Determining a safe range of values for such adjustments is an important quality assurance measure and was the purpose of this study, with focus on stereotactic body radiation therapy in patients with pancreatic cancer. Methods and Materials The retrospective study included 19 previously treated patients. For each fraction, a free-breathing cone beam computed tomography scan was registered to a reference breath-hold computed tomography for alignment to the spine. Two perpendicular breath-hold kV projection images were then acquired and compared with corresponding reference digitally reconstructed radiographs for additional alignment with a surrogate fiducial marker. By comparing the breath-hold kV projection images from subsequent treatment fractions with those from the first fraction, we derived the 3-dimensional variability of the fiducial position with respect to the reference image. Results We observed intrafraction setup error to be within 2.0 mm. For interfraction, we observed average reproducibility of 1.7 ± 0.8 mm, 2.0 ± 1.4 mm, and 3.2 ± 2.5 mm in the left–right (LR), anterior–posterior (AP), and superior–inferior (SI) directions, respectively. The average excursion values from free breathing spine to breath-hold fiducial alignment were 1.5 ± 1.4 mm, 2.0 ± 1.9 mm, and 3.0 ± 2.0 mm in the LR, AP and SI directions, respectively. The observed ranges of average excursions among all patients were 0.2 to 5.1 mm, 0.1 to 5. 9 mm, and 0.6 to 7.8 mm in the LR, AP, and SI directions, respectively. Conclusions This study demonstrates that intrafraction targeting errors can be within 2 mm, and interfraction shifts from free-breathing spine to Active Breathing Coordinator breath-hold target can be as high as 8 mm. Values that deviate significantly would need further investigation to rule out factors such as local progression, bowel gas, or fiducial shift before treatment.

Patients with early-stage nodal follicular lymphoma (FL) may be rendered free of detectable disease by a diagnostic excisional biopsy. We reviewed the management and outcomes of 48 patients with FL, diagnosed from 2003-2013, treated at a single institution. The primary endpoints were local control (LC) and progression-free survival (PFS).Median age at diagnosis was 54.5 years (range 15-74 years). Forty-seven patients were stage I (97.9%); 15 patients (31.3%) had grade 3 disease. Initial management consisted of observation (12 patients; 25.0%), radiation therapy (RT) alone (12 patients; 25.0%), systemic therapy alone (9 cases; 18.8%), or both (15 patients; 31.3%). Median follow-up was 4.92 years (range 0.5-13.83 years). 4-year PFS and OS were 80.9% and 97.1%, respectively. Patients treated with additional therapy experienced significantly better 4-year LC (100% vs. 81.8%

Highlights • MRI-CT deformable image registration was not superior to rigid registration. • Dice similarity coefficients were 0.65, 0.62, and 0.63 for deformable registrations. • Dice similarity coefficient was 0.63 for rigid registration. • Registration quality was superior in muscle and gland compared to bone and vessel., Background MRI-guided radiotherapy planning (MRIgRT) may be superior to CT-guided planning in some instances owing to its improved soft tissue contrast. However, MR images do not communicate tissue electron density information necessary for dose calculation and therefore must either be co-registered to CT or algorithmically converted to synthetic CT. No robust quality assessment of commercially available MR-CT registration algorithms is yet available; thus we sought to quantify MR-CT registration formally. Methods Head and neck non-contrast CT and T2 MRI scans acquired with standard treatment immobilization techniques were prospectively acquired from 15 patients. Per scan, 35 anatomic regions of interest (ROIs) were manually segmented. MRIs were registered to CT rigidly (RIR) and by three commercially available deformable registration algorithms (DIR). Dice similarity coefficient (DSC), Hausdorff distance mean (HD mean) and Hausdorff distance max (HD max) metrics were calculated to assess concordance between MRI and CT segmentations. Each DIR algorithm was compared to DIR using the nonparametric Steel test with control for individual ROIs (n = 105 tests) and for all ROIs in aggregate (n = 3 tests). The influence of tissue type on registration fidelity was assessed using nonparametric Wilcoxon pairwise tests between ROIs grouped by tissue type (n = 12 tests). Bonferroni corrections were applied for multiple comparisons. Results No DIR algorithm improved the segmentation quality over RIR for any ROI nor all ROIs in aggregate (all p values >0.05). Muscle and gland ROIs were significantly more concordant than vessel and bone, but DIR remained non-different from RIR. Conclusions For MR-CT co-registration, our results question the utility and applicability of commercially available DIR over RIR alone. The poor overall performance also questions the feasibility of translating tissue electron density information to MRI by CT registration, rather than addressing this need with synthetic CT generation or bulk-density assignment.

Purpose The aim of this study was to evaluate outcomes of patients who received reirradiation for small skull base tumors utilizing either intensity modulated radiotherapy (IMRT), stereotactic body radiotherapy (SBRT), and proton radiotherapy (PRT). Methods Patients who received IMRT, SBRT or PRT reirradiation for recurrent or new small skull base tumors ( Results Of the 75 patients eligible, 30 (40%) received SBRT, 30 (40%) received IMRT, and 15 (20%) received PRT. The median retreatment volume was 28 cc. The median reirradiation dose was 66 Gy in 33 fractions for IMRT/PRT, and 45 Gy in 5 fractions for SBRT. The median time to reirradiation was 41 months. With a median follow-up of 24 months, the LC, RC, DC, PFS, and OS rates were 84%, 79%, 82%, 60%, and 87% at 1 year, and 75%, 72%, 80%, 49%, and 74% at 2 years. There was no difference in OS between radiation modalities. The 1- and 2-year late Grade 3 toxicity rates were 3% and 11% respectively.. Conclusions Reirradiation of small skull base tumors utilizing IMRT, PRT, or SBRT provided good local tumor control and low rates of Grade 3 late toxicity. A prospective clinical trial is needed to guide selection of radiation treatment modalities.

Magnetic resonance imaging (MRI) has improved capacity to visualize tumor and soft tissue involvement in head and neck cancers. Using advanced MRI, we can interrogate cell density using diffusion weighted imaging, a quantitative imaging that can be used during radiotherapy, when diffuse inflammatory reaction precludes PET imaging, and can assist with target delineation as well. Correlation of circulating tumor cells (CTCs) measurements with 3D quantitative tumor characterization could potentially allow selective, patient-specific response-adapted escalation or de-escalation of local therapy, and improve the therapeutic ratio, curing the greatest number of patients with the least toxicity. The proposed study is designed as a prospective observational study and will collect pretreatment CT, MRI and PET/CT images, weekly serial MR imaging during RT and post treatment CT, MRI and PET/CT images. In addition, blood sample will be collected for biomarker analysis at those time intervals. CTC assessments will be performed on the CellSave tube using the FDA-approved CellSearch® Circulating Tumor Cell Kit (Janssen Diagnostics), and plasma from the EDTA blood samples will be collected, labeled with a de-identifying number, and stored at − 80 °C for future analyses. The primary objective of the study is to evaluate the prognostic value and correlation of weekly tumor response kinetics (gross tumor volume and MR signal changes) and circulating tumor cells of mucosal head and neck cancers during radiation therapy using MRI in predicting treatment response and clinical outcomes. This study will provide landmark information as to the utility of CTCs (‘liquid biopsy) and tumor-specific functional quantitative imaging changes during treatment to guide personalization of treatment for future patients. Combining the biological information from CTCs and the structural information from MRI may provide more information than either modality alone. In addition, this study could potentially allow us to determine the optimal time to obtain MR imaging and/ or CTCs during radiotherapy to assess tumor response and provide guidance for patient selection and stratification for future dose escalation or de-escalation strategies. Clinicaltrials.gov ( NCT03491176 ). Date of registration: 9th April 2018. (retrospectively registered). Date of enrolment of the first participant: 30th May 2017.