Patients who receive radiation therapy sometimes complain of a light flash during irradiation. The details of the characteristics of this light have not been described. To evaluate light flashes during photon and proton radiotherapy. A prospective observational study was performed in all adult patients (≥20 years old) who received photon and proton therapy at two centers between January 2019 and August 2020, except for patients who could not communicate and those with visual abnormality. Evaluations were obtained for the presence or absence of light flashes, light darkness (7 levels), light intensity (5 levels), frequency, light movement, light flashing, and time seeing the light, using a weekly checklist. A total of 650 courses were examined for 621 patients, of whom 416 received photon radiotherapy and 205 received proton beam therapy. The checklist indicated that 88 patients (16.1%) sensed light during photon or proton radiotherapy. In multivariate logistic regression analysis, the factors that were significantly associated with a light flash were a higher retina dose and younger age (p < 0.001). Light flashes were seen by only 35/524 patients (6.7%) for whom the retina was not irradiated, but by 13/33 (39.4%) and 41/64 (64.1%) with maximum isodose lines for the retina of 10–50% and 60–100%, respectively. The numbers of patients who sensed blue, purple, yellow, red, white and other colors were 52, 15, 15, 9, 16 and 8, respectively (multiple selections possible). Light movement was observed by 52 patients (59%). The location of the light was defined as near, far, and middle by 70, 13, and 5 patients, respectively. The median time the light was seen was 10 s. Many patients sense light flashes during radiotherapy. The retina dose and a younger age were significantly associated with the frequency of light flashes.

[Proposal] Here, we retrospectively evaluate risk factors for radiation necrosis and local recurrence after PBT for skull base chordoma or chondrosarcoma. [Patients and Methods] We analyzed 101 patients who received PBT for skull base chordomas and chondrosarcomas from January 1989 to February 2021. Multivariable logistic regression models were applied for local recurrence, temporal lobe radiation necrosis rates, and temporal lobe radiation necrosis. [Results] In multivariate analysis, chordoma and large tumor size were independent significant factors for local recurrence. The 1-, 2-, 3-, 4- and 5-year local recurrence rates were 3.9%, 16.9%, 20.3%, 28.5% and 44.0% for chordoma and 0%, 0%, 0%, 0% and 7.1% for chondrosarcoma, respectively. The local recurrence rates of small tumors (<30 mm) were 4.3%, 14.7%, 17.7%, 17.7% and 25.9%, and those for large tumors were 3.6%, 15.1%, 19.2%, 32.7% and 59.6%, respectively. In multivariate analysis, BED Gy₁₀ and total dose were risk factors for radiation necrosis. [Conclusions] For skull base chordoma and chondrosarcoma, the risk factors of local recurrence were chordoma and large tumor size, and those of radiation necrosis were BED Gy₁₀ and total dose, respectively. DVH analysis is needed to investigate the risk factors for brain necrosis in more detail.

Background: The aim of this study was to develop nomograms predicting 5- and 7-year biochemical-recurrence (BCR)-free survival in high-risk prostate cancer (PCa) patients treated with carbon-ion radiotherapy (CIRT) and androgen deprivation therapy (ADT). Methods: We retrospectively evaluated 785 high-risk PCa patients treated with CIRT and ADT. Based on the least absolute shrinkage and selection operator model, two nomograms predicting 5- and 7-year BCR-free survival were developed and internally validated. The ability of each nomogram to predict BCR-free survival was determined by calculating the area under the survival curve (AUC). Results: The 5- and 7-year BCR-free survival rates were 92.1% and 89.3%, respectively. Age, prostate-specific antigen level, clinical T stage, and Gleason score were incorporated into the nomogram predicting 5-year BCR-free survival. In addition to these variables, the percentage of positive biopsy cores was also added to the nomogram predicting 7-year BCR-free survival. The AUC value of each nomogram showed suboptimal-to-good discrimination. Conclusions: We developed the first nomograms accurately predicting BCR-free survival in high-risk PCa patients treated with CIRT and ADT. These nomograms will enable adequate understanding and explanation of BCR-free survival to patients when clinicians use them.

Background/Objectives: This study evaluated the efficacy and safety of salvage interstitial brachytherapy (S-ISBT) for isolated local recurrence (ILR) of cervical and endometrial carcinoma, stratifying patients by pelvic irradiation history (PIH). Methods: Patients with ILR treated with S-ISBT were retrospectively reviewed and categorized by initial treatment: Group A (surgery alone); Group B (surgery + postoperative radiotherapy (RT)); and Group C (definitive RT). Overall survival (OS), progression-free survival (PFS), local control (LC) rates, and the cumulative incidence functions (CIFs) for Grade ≥ 3 late adverse events (AEs) were estimated. Multivariate analysis identified prognostic factors. Results: The study included 70 patients (A: 28, B: 17, C: 25) with a median follow-up of 33.4 months. The 3-year OS, PFS, LC, and CIFs for Grade ≥ 3 late AEs for Groups A, B, and C were 80.8%, 66.7%, and 30.4% (p < 0.001); 56.4%, 41.5%, and 11.6% (p < 0.001); 89.1%, 61.4%, and 43.0% (p = 0.002); and 26.4%, 13.3%, and 32.0% (p = 0.40), respectively. Multivariate analysis suggested the type of PIH, disease-free interval, and tumor volume as independent prognostic factors. While no significant differences were observed between Groups A and B (OS: HR = 0.47, p = 0.19; PFS: HR = 0.60, p = 0.28), Group C exhibited a significantly higher risk than Group B (OS: HR = 3.08, p = 0.018; PFS: HR = 3.41, p = 0.004). Conclusions: S-ISBT could be considered for patients with prior postoperative RT, whose outcomes are significantly better than those with prior definitive RT.

This study aimed to quantify the continuous association of the mid-treatment MRI-based tumor volume reduction rate (TVRR) with oncologic outcomes after chemoradiation for cervical cancer and to develop prognostic models assessed by two-center internal-external cross-validation (IECV). A retrospective analysis was performed in patients with FIGO 2009 stage IB–IVA disease treated with definitive chemoradiation at two centers from 2010 to 2021 with both pre- and mid-treatment pelvic MRI during external beam radiotherapy (24–36 Gy). Pre- and mid-treatment volumes (Vpre, Vmid) were derived and TVRR was defined as (Vpre − Vmid)/Vpre × 100%. Cox models were used to evaluate overall survival (OS) and progression-free survival (PFS), and a Fine-Gray model was used for local control (LC), modeling TVRR with a penalized spline and adjusting for key covariates. IECV assessed discrimination and 60-month calibration for OS and PFS. The analysis included 281 patients (median age 59 years; squamous cell carcinoma 85%; FIGO 2009 stage III–IV 60%; node-positive 56%) with 65 deaths, 97 PFS events, and 27 local failures over a median follow-up period of 69.6 months. Higher TVRR was independently associated with better outcomes: per 10-percentage-point (pp) increase, OS hazard ratio (HR) 0.71 (95% CI, 0.64–0.79; P < 0.001), PFS HR 0.74 (0.68–0.81; P < 0.001), and LC subdistribution HR 0.68 (0.58–0.80; P < 0.001). Non-linear components were not significant. Discrimination was moderate-high (C 0.73–0.81 internally; 0.72–0.79 in IECV) with acceptable 60-month calibration. In conclusion, mid-treatment MRI-based TVRR provides a strong, near-linear prognostic signal and enables threshold-free, calibrated risk estimation and supports design of risk-adapted trials.

There are no reports on shrinkage of multiple hepatocellular carcinomas (HCCs) after simultaneous treatment with radiotherapy. The purpose of the study was to examine the relationship between tumor shrinkage and treatment outcomes for several HCCs irradiated simultaneously using proton beam therapy (PBT). The subjects were 46 patients with multiple HCCs (95 lesions) who received PBT between January 2008 and December 2018. Overall survival (OS), local control (LC) and complete+partial response (CR + PR) rates were determined using the Kaplan–Meier method. The median follow-up period was 29.2 months and the 3-year OS was 50.3%. For the 95 lesions, the 3-year LC rate was 90.4% and the CR + PR rate was 85.2% at 3 years. Three combination protocols (referred to as A, B and C) were used for different lesions in the same patient: A (66 Gray (Gy) Relative biological effectiveness (RBE) in 10 fractions (fr))-B (72.6 Gy(RBE) in 22 fr) (22 lesions), A-C (74 Gy(RBE) in 37 fr) (15 lesions) and B-C (2 lesions). The 1-year CR + PR rates were 75.8% for A and 56.4% for B in A-B cases (P = 0.14), and 62.5% for A and 57.1% for C in A-C cases (P = 0.35). In the B-C group, there was only one patient with 2 lesions. The lesion treated with the B protocol reached CR + PR, while that treated with the C protocol did not reach CR + PR. These results show that some cases can have differences in tumor shrinkage after concurrent PBT for multiple HCCs, and that there is no significant relationship between dose and tumor shrinkage.