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Background: Interest in the oligometastatic prostate cancer (OMPC) is increasing, and various clinical studies have reported the benefits of metastasis-directed radiation therapy (MDRT) in OMPC. However, the recognition regarding the adopted definitions, methodologies of assessment, and therapeutic approaches is diverse among radiation oncologists. This study aims to evaluate the level of agreement for issues in OMPC among radiation oncologists. Methods: We generated 15 key questions (KQs) for OMPC relevant to definition, diagnosis, local therapies, and endpoints. Additionally, three clinical scenarios representing synchronous metastatic prostate cancer (mPC) (case 1), metachronous mPC with visceral metastasis (case 2), and metachronous mPC with castration-resistance and history of polymetastasis (case 3) were developed. The 15 KQs were adapted according to each scenario and transformed into 23 questions with 6–9 per scenario. The survey was distributed to 80 radiation oncologists throughout the Republic of Korea. Answer options with 0.0–29.9%, 30–49.9%, 50–69.9%, 70–79.9%, 80–89.9%, and 90–100% agreements were considered as no, minimal, weak, moderate, strong, and near perfect agreement, respectively. Results: Forty-five candidates voluntarily participated in this study. Among 23 questions, near perfect (n = 4), strong (n = 3), or moderate (n = 2) agreements were shown in nine. For the case recognized as OMPC with agreements of 93% (case 1), near perfect agreements on the application of definitive radiation therapy (RT) for whole metastatic lesions were achieved. While ≥70% agreements regarding optimal dose-fractionation for metastasis-directed RT (MDRT) has not been achieved, stereotactic body RT (SBRT) is favored by clinicians with higher clinical volume. Conclusion: For the case recognized as OMPC, near perfect agreement for the application of definitive RT for whole metastatic lesions was reached. SBRT was more favored as a MDRT by clinicians with a higher clinical volume.

Summary: Background: Lung cancer diagnostic guidelines advocate for invasive mediastinal nodal staging (IMNS), but the survival benefits of this approach in patients with non-small cell lung cancer (NSCLC) without radiologic evidence of lymph node metastasis (rN0) remain uncertain. We aimed to investigate the impact of IMNS in patients with rN0 NSCLC by comparing the long-term survival between patients who underwent IMNS and those who did not (non-IMNS). Methods: In this retrospective cohort study, we included patients with NSCLC but without radiologic evidence of lymph node metastasis from the Registry for Thoracic Cancer Surgery and the clinical data warehouse at the Samsung Medical Centre, Republic of Korea between January 2, 2008 and December 31, 2016. We compared the 5-year overall survival (OS) rate as the primary outcome after propensity score matching between the IMNS and non-IMNS groups. The age, sex, performance statue, tumor size, centrality, solidity, lung function, FDG uptake in PET-CT, and histological examination of the tumor before surgery were matched. Findings: A total of 4545 patients (887 in the IMNS group and 3658 in the non-IMNS group) who received curative treatment for NSCLC were included in this study. By the mediastinal node dissection, the overall incidence of unforeseen mediastinal node metastasis (N2) was 7.2% (317/4378 patients). Despite the IMNS, 67% of pathological N2 was missed (61/91 patients with unforeseen N2). Based on propensity score matching, 866 patients each for the IMNS and non-IMNS groups were assigned. There was no significant difference in 5-year OS and recurrence-free survival (RFS) between two groups: 5-year OS was 73.9% (95% confidence interval, CI: 71%–77%) for IMNS and 71.7% (95% CI: 68.6%–74.9%; p = 0.23), for non-IMNS (hazard ratio, HR 0.90, 95% CI: 0.77–1.07), while 5-year RFS was 64.7% (95% CI: 61.5%–68.2%) and 67.5% (95% CI: 64.3%–70.9%; p = 0.35 (HR 1.08, 95% CI: 0.92–1.27), respectively. Moreover, the timing and locations of recurrence were similar in both groups. Interpretation: IMNS might not be required before surgery for patients with NSCLC without LN suspicious of metastasis. Further randomised trials are required to validate the findings of the present study. Funding: None.

Abstract Positron emission tomography/computed tomography (PET/CT) with 18F-fluorodeoxyglucose (FDG) is widely used for management of nasopharyngeal carcinoma (NPC). Combining the radiomic features of pre- and post-treatment FDG PET images may improve tumor characterization and prognostic predication. We investigated prognostic value of radiomic features from pre- and post-radiotherapy FDG PET images in patients with NPC. Quantitative radiomic features of primary tumors were extracted from the FDG PET images of 145 NPC patients and the delta values were also calculated. The study population was divided randomly into two groups, the training and test sets (7:3). A random survival forest (RSF) model was adopted to perform analyses of progression-free survival (PFS) and overall survival (OS). There were 37 (25.5%) cases of recurrence and 16 (11.0%) cases of death during a median follow-up period of 54.5 months. Both RSF models with clinical variables and radiomic PET features for PFS and OS showed comparable predictive performance to RSF models with clinical variables and conventional PET parameters. Tumoral radiomic features of pre- and post-treatment FDG PET and the corresponding delta values may predict PFS and OS in patients with NPC.

PurposeTo understand the current practice of radiation oncologists (ROs) and orthopedic surgeons (OSs) regarding spine metastasis.MethodsIn 2022, an internet-based survey was conducted for ROs and OSs who treat spinal metastasis in Korea. Respondents were asked to choose the treatment option for two clinical scenarios. Scenario 1 involved a case displaying symptoms of leg weakness due to spinal cord compression and Scenario 2 involved a case with back pain due to pathologic compression fracture. The survey also included a question that required respondents to rank the importance of 11 clinical factors that affect treatment decisions.ResultsForty-nine ROs and 30 OSs responded to the survey. There were significant differences in treatment choices between two groups for both scenarios (P = 0.001). In Scenario 1, more OSs chose surgical resection than ROs (43.3% vs. 16.7%), while more ROs chose radiotherapy than OSs (83.3% vs. 53.3%). In Scenario 2, a similar proportion of OSs and ROs chose radiotherapy (OSs, 71.4% vs. ROs, 67.3%), while more OSs opted for prophylactic fixation after radiotherapy than ROs (95.0% vs. 42.4%). The top three factors influencing treatment decisions were general performance status, life expectancy, and spinal instability for both ROs and OSs. In both Scenarios 1 and 2, the treatment decisions of ROs changed significantly when clinical conditions related to these top three factors were altered.ConclusionAlthough ROs and OSs share the same factors influencing treatment decisions for spinal metastases, notable differences exist in their actual treatment preferences, with ROs preferring radiotherapy and OSs opting for surgical resection. Multidisciplinary discussions may be necessary to reduce the gap in decision-making.

Abstract Background To compare the dosimetric profiles of volumetric modulated arc therapy (VMAT) plans using the fast-rotating O-ring linac (the Halcyon system) based on a dual-layer stacked multi-leaf collimator and helical tomotherapy (HT) for nasopharyngeal cancer (NPCa). Methods For 30 NPCa patients, three sets of RT plans were generated, under the same policy of contouring and dose constraints: HT plan; Halcyon VMAT plan with two arcs (HL2arc); and Halcyon VMAT plan with four arcs (HL4arc), respectively. The intended dose schedule was to deliver 67.2 Gy to the planning gross target volume (P-GTV) and 56.0 Gy to the planning clinical target volume (P-CTV) in 28 fractions using the simultaneously integrated boost concept. Target volumes and organ at risks dose metrics were evaluated for all plans. Normal tissue complication probabilities (NTCP) for esophagus, parotid glands, spinal cord, and brain stem were compared. Results The HT plan achieved the best dose homogeneity index for both P_GTV and P_CTV, followed by the HL4arc and L2arc plans. No significant difference in the dose conformity index (CI) for P_GTV was observed between the HT plan (0.80) and either the HL2arc plan (0.79) or the HL4arc plan (0.83). The HL4arc plan showed the best CI for P_CTV (0.88), followed by the HL2arc plan (0.83) and the HT plan (0.80). The HL4arc plan (median, interquartile rage (Q1, Q3): 25.36 (22.22, 26.89) Gy) showed the lowest Dmean in the parotid glands, followed by the HT (25.88 (23.87, 27.87) Gy) and HL2arc plans (28.00 (23.24, 33.99) Gy). In the oral cavity (OC) dose comparison, the HT (22.03 (19.79, 24.85) Gy) plan showed the lowest Dmean compared to the HL2arc (23.96 (20.84, 28.02) Gy) and HL4arc (24.14 (20.17, 27.53) Gy) plans. Intermediate and low dose regions (40–65% of the prescribed dose) were well fit to the target volume in HL4arc, compared to the HT and HL2arc plans. All plans met the dose constraints for the other OARs with sufficient dose margins. The between-group differences in the median NTCP values for the parotid glands and OC were

The aim of this study was to evaluate the dosimetric characteristics of a semi-customized tongue displacement device (SCTDD) fabricated using a 3D printer for patients receiving unilateral head and neck irradiation with intensity-modulated proton therapy (IMPT) and assess its feasibility as a proton beam stopper compared to a standard mouthpiece (SMP). Seven consecutive patients, three with tonsil cancer, and four with oral cavity cancer were included in this retrospective study. Planning computed tomography (CT) images of each patient were acquired for each device. Both the SCTDD and SMP plans were generated using a single-field optimized IMPT. The clinically relevant dose-volume parameters for the organs at risk (OARs), especially the tongue, were compared between the SCTDD and SMP plans. Additionally, to assess the feasibility of SCTDD as a proton beam stopper, the dose to the contralateral oral mucosa (COM) was compared with that from sMP use. The use of scTDD resulted in a statistically significant decrease in the radiation dose to the tongue and COM compared to sMP. The median mean dose to the tongue was significantly reduced with SCTDD (18.3 Gy(RBE)) compared to the SMP (22.9 Gy(RBE)) (p = 0.016). The percentages of tongue volume receiving doses between 15 and 60 Gy(RBE) were significantly lower with SCTDD. In the COM, SCTDD resulted in a significantly lower median mean (2.9 Gy(RBE) vs. 7.9 Gy(RBE), p = 0.018) and maximum dose (39.1 Gy(RBE) vs. 41.6 Gy(RBE), p = 0.018) doses compared to SMP. The SCTDD effectively decreased the radiation dose to the tongue compared to SMP in patients undergoing unilateral head and neck irradiation with IMPT and acted as a proton beam stopper to protect normal tissues located behind the target volume, such as the COM.

Abstract Background and objective This study aims to evaluate the impact of diffusing capacity of the lung for carbon monoxide (DLco) before and after neoadjuvant concurrent chemoradiotherapy (CCRT) on postoperative pulmonary complication (PPC) among stage IIIA/N2 non-small-cell lung cancer (NSCLC) patients. Methods We retrospectively studied 324 patients with stage IIIA/N2 NSCLC between 2009 and 2016. Patients were classified into 4 groups according to DLco before and after neoadjuvant CCRT; normal-to-normal (NN), normal-to-low (NL), low-to-low (LL), and low-to-very low (LVL). Low DLco and very low DLco were defined as DLco

Purpose: There is increasing interest in the efficacy of stereotactic ablative radiotherapy (SABR) for treating colorectal cancer (CRC) patients with oligometastases (OM), recently. The purpose of this meta-analysis was to evaluate local control (LC), progression-free survival (PFS), and overall survival (OS) of CRC patients with pulmonary OM treated with SABR and toxicities. Materials and Methods: Studies that reported SABR for CRC patients with pulmonary OM were searched from MEDLINE and Embase. Treatment outcomes including LC, PFS, OS, and toxicities of grade 3 or higher were assessed. Results: A total of 19 studies with 1,668 patients were chosen for this meta-analysis. Pooled 1-, 2-, and 3-year LC rates were 83.1%, 69.3%, and 63.9%, respectively. PFS rates were 44.8%, 26.5%, and 21.5% at 1, 2, and 3 years, respectively. OS rates at 1-, 2-, and 3-year were 87.5%, 69.9%, and 60.5%, respectively. The toxicity rate of grade 3 or higher was 3.6%. The effect of dose escalation was meta-analyzed using available studies. Conclusion Application of SABR to CRC patients with pulmonary OM achieved modest local control with acceptable toxicity according to the present meta-analysis. Further studies establishing the clinical efficacy of SABR are guaranteed. [ABSTRACT FROM AUTHOR]

Abstract Purpose To reduce radiation doses to the tongue, a patient-specific semi-customized tongue displacement device (SCTDD) was developed using a 3D printer (3DP) for head and neck (H&N) radiation therapy (RT). Dosimetric characteristics of the SCTDD were compared with those of a standard mouthpiece (SMP). Materials and methods The SCTDD consists of three parts: a mouthpiece, connector with an immobilization mask, and tongue displacer, which can displace the tongue to the contralateral side of the planning target volume. Semi-customization was enabled by changing the thickness and length of the SCTDD. The instrument was printed using a 3DP with a biocompatible material. With the SCTDD and SMP, two sets of planning computed tomography (CT) and tomotherapy plans were obtained for seven H&N cancer patients. Dosimetric and geometric characteristics were compared. Results Using the SCTDD, the tongue was effectively displaced from the planning target volume without significant tongue volume change compared to the SMP. The median tongue dose was significantly reduced (29.6 Gy vs. 34.3 Gy). The volumes of the tongue receiving a dose of 15 Gy, 30 Gy, 35 Gy, 45 Gy, and 60 Gy were significantly lower than using the SMP. Conclusion The SCTDD significantly decreased the radiation dose to the tongue compared to the SMP, which may potentially reduce RT-related tongue toxicity.

Objectives: This analysis was performed to evaluate the incidence of vertebral compression fracture (VCF) and determine the contributing factors for VCF in patients undergoing single-fraction stereotactic body radiotherapy (SBRT) for spinal bone metastases (SBM). Methods: A retrospective review of medical records was conducted for patients undergoing SBRT for SBM at our institution between January 2010 and December 2018. Patients who had undergone neither pre-SBRT surgical excision nor post-SBRT prophylactic fixation were included. The effects of clinical and dosimetric parameters were analyzed with respect to VCF risk. The following dosimietric parameters of the planning target volume (PTV) were calculated: mean/minimum/maximum dose, radiation dose to 10–90% volume, and irradiated volume receiving more than 10–25 Gy (PTV_V10 – 25 Gy). Results: Among 163 patients (179 vertebrae), 21 (12.8%) experienced VCF. The 1-year and 2-year VCF rates were 12.1% and 13.2%, respectively. Among dosimetric parameters, PTV_V15 Gy was the most significant for VCF prediction. In a univariate analysis, breast or prostate primary, no vertebral body collapse, and PTV_V15 Gy ≤42 cm3 were significantly associated with a lower incidence rate of VCF. In a multivariate analysis, PTV_V15 Gy was the only significant factor for VCF risk. The 1-year VCF rate was 3.8% in patients with PTV_V15 Gy ≤42 cm3, while it was 22.1% in those with PTV_V15 Gy > 42 cm3 (p

Background/Aims Clinical trials have not consistently supported the use of induction chemotherapy (IC) for locally advanced head and neck squamous cell cancer. Hypopharynx and base of tongue (BOT) cancer has shown relatively poor survival. We investigated the role of IC in improving outcome over current chemoradiotherapy (CRT) in patients with hypopharynx and BOT cancer. Methods Treatment-naïve patients with stage III/IV (M0) hypopharynx or BOT cancer were randomly assigned to receive CRT alone (CRT arm: cisplatin 100 mg/m2 on D1 3-weekly, two times plus radiotherapy 68.4 Gy/30 fractions on weekdays) versus two 21-day cycles of IC with TPF (docetaxel & cisplatin 75 mg/m2 on D1, and fluorouracil 75 mg/m2 on D1-4) followed by the same CRT regimen (IC arm). The primary endpoint was progression-free survival (PFS). Results This study closed early after enrollment of 36 patients (19 in the CRT arm, 17 in the IC arm). After a median follow-up of 47.2 months, there was no significant difference in PFS: the median PFS was 26.8 months for the CRT arm and was not reached for the IC arm (p = 0.13). However, the survival curves were widely separated with a plateau after 3 years, suggesting a potential survival benefit from IC: 3-year PFS rates were 45% and 68%, and 3-year overall survival rates were 56% and 86%, in the CRT and IC arms, respectively. Conclusions This study failed to demonstrate that induction TPF chemotherapy improves survival in patients with BOT and hypopharynx cancer. However, it suggested a favorable outcome with IC to this population.

This study evaluated the toxicity associated with radiation techniques on curative re-irradiation (re-RT) in patients with thoracic recurrence of non-small cell lung cancer (NSCLC). From 2011 to 2019, we retrospectively reviewed the data of 63 patients with salvage re-RT for in-field or marginal recurrence of NSCLC at two independent institutions. Re-RT techniques using X-ray beams and proton beam therapy (PBT) were also included. Re-RT had a 2-year overall survival (OS) and local progression-free survival of 48.0% and 52.0%, respectively. Fifteen patients experienced grade 3 or higher toxicity after re-RT. The complication rates were 18.2% (4/22) and 26.8% (11/41) in PBT patients and X-ray patients, respectively. Airway or esophageal fistulas occurred in seven patients (11.1%). Fistulas or severe airway obstruction occurred in patients with tumors adjacent to the proximal bronchial tree and esophagus, who underwent hypofractionated radiotherapy (RT) or concurrent chemotherapy, and with a higher dose exposure to the esophagus. In conclusion, salvage re-RT was feasible even in patients with local recurrence within the previous RT field. PBT showed similar survival outcomes and toxicity to those of other techniques. However, thoracic re-RT should be performed carefully considering tumor location and RT regimens such as the fraction size and concurrent chemotherapy.

Abstract Background Oesophageal cancer with airway invasion presents a challenge for therapy and often has serious complications. We analysed the clinical outcomes of radiation therapy (RT) in patients with clinical T4b oesophageal cancer with airway invasion. Methods We retrospectively reviewed the medical records of 73 patients with oesophageal cancer who had clinical T4 disease and who received RT between January 1994 and June 2017. Among them, 47 patients with clinical T4b disease with airway invasion were included in this study; 31 had gross invasion on bronchoscopy and 16 had extrinsic compression with mucosal change. We investigated the survival outcomes, clinical courses, and toxicities. Results The median survival (MS) time was 9 months. The 1- and 2-year overall survival (OS) rates were 41.4 and 27.4%, respectively. The MS times for patients treated with curative or palliative aims were 15 and 4 months, respectively (p = 0.001). Seven patients (14.9%) had fistulae at diagnosis; after RT, three had no change in size, three closed, and one had increased. Newly developed oesophageal fistulae after treatment were observed in 13 patients (27.7%). The median time to a newly developed fistula was 3 months (range, 1–15). Among them, a fistula was closed in only one patient. Death from aspiration pneumonia occurred in one patient who had a fistula at diagnosis and in nine patients who newly developed fistulae after treatment. Severe oesophageal bleeding causing death occurred in two patients. Patients with gross invasion on bronchoscopy had a higher risk of developing a fistula than did patients with mucosal change (37.5% vs. 25.0%, respectively). Conclusions Even for clinical T4b disease with airway invasion, RT with a curative aim showed acceptable survival outcomes in patients with good performance status and no distant metastasis at initial diagnosis. However, the risk of fistula development associated with fatal events remains high. Further study is warranted to decrease the risks of treatment and improve clinical outcomes. Trial registration Retrospectively registered.

Purpose: This retrospective study aimed to compare clinical outcomes and dosimetric parameters between radiation therapy (RT) techniques in patients with thymic epithelial tumor (TET). Materials and Methods: From January 2016 to December 2020, 101 patients with TET received adjuvant RT (median, 52.8 Gy; range, 48.4 to 66.0). Three different RT techniques were compared: three-dimensional conformal RT (3D-CRT; n = 59, 58.4%), intensity-modulated RT (IMRT; n = 23, 22.8%), and proton beam therapy (PBT; n = 19, 18.8%). Results: The median age of the patients and the follow-up period were 55 years (range, 28 to 79) and 43.4 months (range, 7.7 to 77.2). Patients in the PBT group were of the youngest age (mean age, 45.4 years), while those in IMRT group had the largest clinical target volume (mean volume, 149.6 mL). Patients in the PBT group had a lower mean lung dose (4.4 Gy vs. 7.6 Gy vs. 10.9 Gy, respectively; p < 0.001), lower mean heart dose (5.4 Gy vs. 10.0 Gy vs. 13.1 Gy, respectively; p = 0.003), and lower mean esophageal dose than patients in the 3D-CRT and IMRT groups (6.3 Gy vs. 9.8 Gy vs. 13.5 Gy, respectively; p = 0.011). Twenty patients (19.8%) showed disease recurrence, and seven patients (6.9%) died. The differences in the survival rates between RT groups were not statistically significant. Conclusion: In patients with TET who underwent adjuvant RT, PBT resulted in a lower dose of exposure to adjacent organs at risk. Survival outcomes for patients in PBT group were not significantly different from those in other groups. [ABSTRACT FROM AUTHOR]

Abstract Purpose Radiation pneumonitis (RP) has been a challenging obstacle in treating stage III lung cancer patients. Beam angle optimization (BAO) technique for Tomotherapy was developed to reduce the normal lung dose for stage III non-small cell lung cancer (NSCLC). Comparative analyses on plan quality by 3 different Intensity-modulated radiation therapy (IMRT) methods with BAO were done. Materials and methods Ten consecutive stage IIIB NSCLC patients receiving linac-based static IMRT (L-IMRT) with total 66 Gy in 33 fractions to the PTV were selected. Two additional Tomotherapy-based IMRT plans (helical beam (TH-IMRT) and static beam (TD-IMRT)) were generated on each patient. To reduce the normal lung dose, Beam angles were optimized by using complete and directional block functions in Tomotherapy based on knowledge based statistical analysis. Plan quality was compared with target coverage, normal organ sparing capability, and normal tissue complication probability (NTCP). Actual beam delivery times and risk of RP related with planning target volume (PTV) were also evaluated. Results The best PTV coverage measured by conformity index and homogeneity index was achievable by TH-IMRT (0.82 and 1.06), followed by TD-IMRT (0.81 and 1.07) and L-IMRT (0.75 and 1.08). Mean lung dose was the lowest in TH-IMRT plan followed by TD-IMRT and L-IMRT, all of which were ≤20 Gy. TH-IMRT plan could significantly lower the lung volumes receiving low to medium dose levels: V5~30 when compared to L-IMRT plan; and V5~20 when compared to TD-IMRT plan, respectively. TD-IMRT plan was significantly better than L-IMRT with respects to V20 and V30 and there was no significant difference with respect to V40 among three plans. The NTCP of the lung was the lowest in TH-IMRT plan, followed by TD-IMRT and L-IMRT (6.42% vs. 6.53% vs. 8.11%). Beam delivery time was the shortest in TD-IMRT plan followed by L-IMRT. As PTV length increased, NTCP and Mean lung dose proportionally increased significantly in all three plans. Conclusion Advantageous profiles by TH-IMRT could be achieved by BAO by complete and directional block functions. Current observation could help radiation oncologists to make wise selection of IMRT method for stage IIIB NSCLC.

Abstract Background Treatment of tonsil cancer, a subset of oropahryngeal cancer, varies between surgery and radiotherapy. Well-designed studies in tonsil cancer have been rare and it is still controversial which treatment is optimal. This study aimed to assess the outcome and failure patterns in tonsil cancer patients treated with either approaches. Methods We retrospectively reviewed medical records of 586 patients with tonsil cancer, treated between 1998 and 2010 at 16 hospitals in Korea. Two hundred and one patients received radiotherapy and chemotherapy (CRT), while 385 patients received surgery followed by radiotherapy and/or chemotherapy (SRT). Compared with the SRT group, patients receiving CRT were older, with more advanced T stage and received higher radiotherapy dose given by intensity modulation techniques. Overall survival (OS), disease-free survival (DFS), locoregional recurrence-free survival (LRRFS), distant metastasis-free survival (DMFS), and clinicopathologic factors were analyzed. Results At follow-up, the 5-year OS, DFS, LRRFS and DMFS rates in the CRT group were 82, 78, 89, and 94%, respectively, and in the SRT group were 81, 73, 87, and 89%, respectively. Old age, current smoking, poor performance status, advanced T stage, nodal involvement, and induction chemotherapy were associated with poor OS. Induction chemotherapy had a negative prognostic impact on OS in both treatment groups (p = 0.001 and p = 0.033 in the CRT and SRT groups, respectively). Conclusions In our multicenter, retrospective study of tonsil cancer patients, the combined use of radiotherapy and chemotherapy resulted in comparable oncologic outcome to surgery followed by postoperative radiotherapy, despite higher-risk patients having been treated with the definitive radiotherapy. Induction chemotherapy approaches combined with either surgery or definitive radiotherapy were associated with unfavorable outcomes.

Purpose: We aimed to compare the oncological outcomes and toxicities of definitive proton beam therapy (PBT) and photon beam therapy in patients with limited-stage small cell lung cancer (LSSCLC). Materials and Methods: We retrospectively reviewed 262 patients with newly diagnosed LS-SCLC who underwent definitive PBT (n = 20; proton group) or photon beam therapy (n = 242; photon group) with concurrent chemotherapy between January 2016 and February 2021 and compared overall survival (OS), progression-free survival (PFS), dose-volume parameters, and toxicities between the groups. Results: The median follow-up duration was 24.5 months (range, 3.7 to 78.7). Baseline lung function was significantly worse and clinical target volume (CTV) was larger in the proton group (CTV: 296.6 vs. 215.3 mL; p = 0.080). The mean lung V10 was 37.7% ± 16.8% and 51.6% ± 24.5% in the proton and photon groups, respectively (p = 0.002). Two-year OS and PFS rates were 57.2% and 35.7% in the proton group and 65.3% and 40.8% in the photon group, respectively (p = 0.542 and 0.748, respectively). Grade =2 radiation pneumonitis and esophagitis occurred in 5 (25.0%) and 7 (35.0%) PBT-treated patients and 66 (27.3%) and 40 (16.5%) photon beam therapy-treated patients, respectively (p = 0.826 and 0.062, respectively). Conclusion: Although the proton group had poorer lung function and a larger CTV than that in the photon group, both groups exhibited comparable treatment outcomes and radiation-related toxicities in LS-SCLC. PBT may be a valuable therapeutic modality in patients with poor pulmonary function or extensive disease burden owing to its lung-sparing ability. [ABSTRACT FROM AUTHOR]

Purpose: In outbreaks of infectious disease, medical students are easily overlooked in the management of healthcare personnel protection although they serve in clinical clerkships in hospitals. In the early summer of 2015, Middle East respiratory syndrome (MERS) struck South Korea, and students of Sungkyunkwan University School of Medicine (SKKUSOM) were at risk of contracting the disease. The purpose of this report is to share SKKUSOM’s experience against the MERS outbreak and provide suggestions for medical schools to consider in the face of similar challenges. Methods: Through a process of reflection-on-action, we examined SKKUSOM’s efforts to avoid student infection during the MERS outbreak and derived a few practical guidelines that medical schools can adopt to ensure student safety in outbreaks of infectious disease. Results: The school leadership conducted ongoing risk assessment and developed contingency plans to balance student safety and continuity in medical education. They rearranged the clerkships to another hospital and offered distant lectures and tutorials. Five suggestions are extracted for medical schools to consider in infection outbreaks: instant cessation of clinical clerkships; rational decision making on a school closure; use of information technology; constant communication with hospitals; and open communication with faculty, staff, and students. Conclusion: Medical schools need to take the initiative and actively seek countermeasures against student infection. It is essential that medical schools keep constant communication with their index hospitals and the involved personnel. In order to assure student learning, medical schools may consider offering distant education with online technology.

ObjectivesThe aim of this study was to evaluate the prognostic value of volume-based metabolic parameters measured by 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) in patients with nasopharyngeal carcinoma (NPC).MethodsForty-four NPC patients who underwent 18F-FDG PET/CT for initial staging work-up before concurrent chemoradiotherapy (CCRT) were retrospectively evaluated. Maximum standardized uptake value (SUV), mean SUV, metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of the primary tumors were measured. The prognostic significance and predictive performance of these parameters were assessed by Cox proportional hazards regression analysis and time-dependent receiver operating characteristics (ROC) curve analysis.ResultsMultivariate analysis showed that American Joint Committee on Cancer stage 7th edition (hazard ratio [HR], 1.525; 95% confidence interval [CI], 1.062 to 2.188; P=0.022), and TLG (HR, 7.799; 95% CI, 2.622 to 23.198; P≤0.001) were independent predictive factors associated with decreased disease-free survival (DFS). Time-dependent ROC curve analysis indicated that TLG was a better predictor of DFS than MTV (P=0.008).ConclusionThe TLG of the primary tumor was a significant independent metabolic prognostic factor of DFS in patients with NPC treated with CCRT.

Purpose Stereotactic body radiotherapy (SBRT) had been increasingly recognized as a favorable alternative to surgical resection in patients with high risk for surgery. This study compared survival outcomes between sublobar resection (SLR) and SBRT for clinical stage I non--small cell lung cancer (NSCLC). Materials and Methods Data were obtained from the Korean Association of Lung Cancer Registry, a sampled nationwide database. This study retrospectively reviewed 382 patients with clinical stage I NSCLC who underwent curative SLR or SBRT from 2014 to 2016. Results Of the patients, 43 and 339 underwent SBRT and SLR, respectively. Patients in the SBRT group were older and had worse pulmonary function. The 3-year overall survival (OS) rate was significantly better in the SLR group compared with the SBRT group (86.6% vs. 57%, log-rank p < 0.001). However, after adjusting for age, sex, tumor size, pulmonary function, histology, smoking history, and adjuvant therapy, treatment modality was not an independent prognostic factor for survival (hazard ratio, 0.99; 95% confidence interval, 0.43 to 2.77; p=0.974). We performed subgroup analysis in the following high-risk populations: patients who were older than 75 years; patients who were older than 70 years and had diffusing capacity of lung for carbon monoxide ≤ 80%. In each subgroup, there were no differences in OS and recurrence-free survival between patients who underwent SLR and those who received SBRT. Conclusion In our study, there were no significant differences in terms of survival or recurrence between SBRT and SLR in medically compromised stage I NSCLC patients. Our findings suggest that SBRT could be considered as a potential treatment option for selected patients. [ABSTRACT FROM AUTHOR]

Purpose Despite numerous studies on the optimal treatments for oligometastatic disease (OMD), there is no established interdisciplinary consensus on its diagnosis or classification. This survey-based study aimed to analyze the differential opinions of colorectal surgeons and radiation oncologists regarding the definition and treatment of OMD from the colorectal primary. Materials and Methods A total of 141 participants were included in this study, consisting of 63 radiation oncologists (44.7%) and 78 colorectal surgeons (55.3%). The survey consisted of 19 questions related to OMD, and the responses were analyzed using the chi-square test to determine statistical differences between the specialties. Results The radiation oncologists chose "bone" more frequently compared to the colorectal surgeons (19.2% vs. 36.5%, p=0.022), while colorectal surgeons favored "peritoneal seeding" (26.9% vs. 9.5%, p=0.009). Regarding the number of metastatic tumors, 48.3% of colorectal surgeons responded that "irrelevant, if all metastatic lesions are amendable to local therapy", while only 21.8% of radiation oncologist chose same answer. When asked about molecular diagnosis, most surgeons (74.8%) said it was important, but only 35.8% of radiation oncologists agreed. Conclusion This study demonstrates that although radiation oncologists and colorectal surgeons agreed on a majority of aspects such as diagnostic imaging, biomarker, systemic therapy, and optimal timing of OMD, they also had quite different perspectives on several aspects of OMD. Understanding these differences is crucial to achieving multidisciplinary consensus on the definition and optimal management of OMD. [ABSTRACT FROM AUTHOR]

Introduction of the concept for oligometastasis led to wide application of metastasis-directed local ablative therapies for metastatic colorectal cancer (CRC). By application of the metastasis-directed local ablative therapies including surgical resection, radiofrequency ablation (RFA), and stereotactic ablative body radiotherapy (SABR), the survival outcomes of patients with metastatic CRC have improved. The liver is the most common distant metastatic site in CRC patients, and recently various metastasis-directed local therapies for hepatic oligometastasis from CRC (HOCRC) are widely used. Surgical resection is the first line of metastatic-directed local therapy for HOCRC, but its eligibility is very limited. Alternatively, RFA can be applied to patients who are ineligible for surgical resection of liver metastasis. However, there are some limitations such as inferior local control (LC) compared with surgical resection and technical feasibility based on location, size, and visibility on ultrasonography of the liver metastasis. Recent advances in radiation therapy technology have led to an increase in the use of SABR for liver tumors. SABR is considered complementary to RFA for patients with HOCRC who are ineligible for RFA. Furthermore, SABR can potentially result in better LC for liver metastases > 2-3 cm compared with RFA. In this article, the previous studies regarding curative metastasis-directed local therapies for HOCRC based on the radiation oncologist's and surgeon's perspective are reviewed and discussed. In addition, future perspectives regarding SABR in the treatment of HOCRC are suggested. [ABSTRACT FROM AUTHOR]

Purpose This study aimed to investigate cumulative incidence and risk factors associated with chronic pulmonary infection (CPI) development after radiotherapy for lung cancer. Materials and Methods We retrospectively analyzed 1,872 patients with lung cancer who received radiotherapy for lung cancer from 2010-2014, had a follow-up period of = 3 months after radiotherapy, and did not have CPI at the time of radiotherapy. CPI was defined as pulmonary tuberculosis, non-tuberculous mycobacterial pulmonary disease, chronic pulmonary aspergillosis, or pulmonary actinomycosis. The cumulative incidence of CPI and overall survival (OS) were estimated using the Kaplan-Meier method, and a multivariable Cox proportional hazards analysis was performed to identify risk factors associated with CPI development. Results The median follow-up period was 2.3 years with OS rates of 55.6% and 37.6% at 2 and 5 years, respectively. CPI developed in 59 patients at a median of 1.8 years after radiotherapy, with cumulative incidence rates of 1.1%, 3.4%, 5.0%, and 6.8% at 1, 3, 5, and 7 years, respectively. A lower body mass index, interstitial lung disease, prior pulmonary tuberculosis, larger clinical target volume, history of lung cancer surgery or radiation pneumonitis, and use of inhaled corticosteroids were independent risk factors for CPI development. Conclusion The long-term survival rate of lung cancer patients receiving radiotherapy was not low, but the cumulative incidence of CPI gradually increased to 6.8% at 7 years after radiotherapy. Therefore, close monitoring of CPI development is required in surviving patients with risk factors. [ABSTRACT FROM AUTHOR]

ObjectivesThe authors would report the results of definitive radiation therapy (RT) for early glottic cancer by two different radiation dose schedules.MethodsFrom February of 1995 till June of 2008, 157 patients with T1-2N0 glottic cancer were treated with curative RT at Samsung Medical Center. All patients had squamous cell carcinoma, and there were 89 patients (56.7%) with T1a, 36 (22.9%) with T1b, and 32 (20.4%) with T2. Two different radiation dose schedules were used: 70 Gy in 35 fractions to 64 patients (40.8%, group A); and 67.5 Gy in 30 fractions to 93 patients (59.2%, group B). The median treatment durations were 50 days (range, 44 to 59 days) and 44 days (range, 40 to 67 days) in the groups A and B, respectively.ResultsThe median follow-up durations were 85 and 45 months for the groups A and B. No severe late complication of RTOG grade 3 or higher was observed, and there was no difference in acute or chronic complication between the groups. Twenty-four patients experienced treatment failure: local recurrence only in 19 patients; regional recurrence only in one; combined local and regional recurrence in four; and systemic metastasis in none. The overall 5-year disease-free survival and disease-specific survival rates were 84.7% and 94.8%. The disease-free survival rate in the group B was better (78.3% vs. 90.8%, P=0.031). This difference was significant only in T1 stage (83.4% vs. 94.6%, P=0.025), but not in T2 (62.7% vs. 60.6%, P=0.965). Univariate analysis showed that the tumor extent, cord mobility, T-stage, and the dose schedule had significant influence on the disease-free survival, and multivariate analysis showed that only the tumor extent and the dose schedule were associated with the disease-free survival.ConclusionSuperior disease-free survival could be achieved by 2.25 Gy per fraction without increased toxicity over shorter RT duration, when compared with 2.0 Gy per fraction.

ObjectivesThis is to report treatment results of major salivary gland cancer by surgery with or without postoperative radiation therapy (PORT).MethodsBetween March 1995 and January 2006, 94 patients with primary major salivary cancer underwent curative surgical resection at Samsung Medical Center. The parotid gland was the most commonly involved (73, 77.7%), followed by the submandibular and the sublingual. Neck dissection was added in 28 patients, and PORT was individually recommended to those with risk factors. Seventy-five (79.8%) patients received PORT. PORT volume included primary tumor bed and pathologically involved regional lymphatics, and no additional effort was made for elective nodal irradiation. The median total doses were 56.0 Gy to primary site and 58.7 Gy to regional lymphatics.ResultsAfter median follow-up of 49 months, 21 patients had relapsed: 20 in PORT; and one in surgery alone group. As the first site of failure, distant metastasis was the most common (17 patients). Local recurrence occurred in three, and regional relapse in one. The lung was the most common site (10 patients), followed by the bone, and the brain. Five-yr disease free survival (DFS), local control, and overall survival (OS) rates were 74.4% and 94.7%, 96.0% and 100%, and 78.2% and 100% in PORT and surgery alone groups, respectively. On multivariate analysis, DFS was significantly affected by pN+ (hazard ratio [HR], 3.624; P=0.0319), while OS was by pN+ (HR, 7.138; P=0.0034) and perineural invasion (HR, 5.073; P=0.0187).ConclusionBased on our experience, the patients with early stage major salivary gland cancer with low risk can be effectively treated by surgery alone, and those who with risk factors can achieve excellent local and regional control by adding PORT. Omitting elective neck irradiation in patients with N0 disease seems a feasible strategy under accurate clinical evaluation. An effort is needed to decrease distant metastasis through further clinical trials.