BACKGROUND:In boron neutron capture therapy (BNCT), Monte Carlo (MC) dose calculations are commonly employed because of the complicated neutron reactions. However, MC dose calculations are generally time-consuming. Recently, deep learning (DL)-based dose prediction/calculation has attracted increasing attention; however, the applications of DL models in BNCT are limited and have not been investigated extensively. In addition, there are no practical DL models that can be employed in BNCT clinical practice. PURPOSE:We propose a practical DL model for head and neck cancers using a commercial treatment planning system (TPS) for BNCT. To increase the speed of the MC dose calculations, the proposed DL model converts the BNCT dose components calculated by the coarse dose calculation grid size and low statistical uncertainty in the MC calculation into the dose components calculated under the fine setting. METHODS:In this study, we considered 114 head and neck cancer patients who underwent accelerator-based BNCT at our center. Here, we randomly divided 102 patients for training/validation and 12 patients for testing. The BNCT dose components (i.e., boron, nitrogen, hydrogen, and gamma doses) were calculated for all patients using a commercial TPS for BNCT. We employed the hierarchically dense U-net and converted the BNCT dose components calculated by the coarse setting (grid size/uncertainty = 5 mm/10%) into doses calculated by the fine setting (2 mm/5%). In addition, a physical density map was added to the DL input to improve the conversion accuracy. Taking the fine dose as the ground truth, we evaluated the γ-passing rates with various criteria for each dose component of the coarse and DL doses. The calculation time was also measured in the fine, coarse, and DL doses. RESULTS:In the boron dose, the DL dose exhibited significantly higher γ-passing rates of ≥ 95% with a criterion of 1%/2 mm (dose difference/distance to agreement) than the coarse dose. In the nitrogen and hydrogen doses, the DL dose also demonstrated high γ-passing rates of 95.3% and 94.7% with a criterion of 5%/2 mm. The density map was effective for the hydrogen and nitrogen doses. In addition, the average γ-passing rate with the criterion of 3%/2 mm in the gamma dose achieved 96.2% for the DL dose. The average calculation times for the fine and coarse settings were 984.2 ± 470.2 min and 11.0 ± 2.9 min, respectively, and the average conversion time in the DL model was 0.091 ± 0.020 min. CONCLUSIONS:In this study, the proposed DL model was developed to convert each dose component calculated in the coarse setting to the fine dose to increase the speed of commercial MC dose calculations in BNCT for head and neck cancers. The conversion speed from the coarse dose to the fine dose was considerably rapid, and its performance was highly accurate. The proposed DL model can provide accurate BNCT dose distributions at high speed, thereby contributing to improving the quality of BNCT treatment planning.

The feasibility and safety of a second course of boron neutron capture therapy (BNCT) are unknown. In this study, we retrospectively analyzed the treatment outcomes and toxicities in recurrent head and neck cancer (RHNC) patients who underwent BNCT twice at Southern TOHOKU BNCT Research Center. In total, 33 patients who underwent BNCT twice for RHNC at Southern TOHOKU BNCT Research Center between June 2020 and March 2024 were included. The indications for second BNCT were local recurrence or residual tumor after the first course. Eligible patients either declined salvage surgery or had no curative treatment options other than second BNCT. The median age was 65 years (range, 23-84 years), and the median interval from the first to the second BNCT was 4.1 months (range, 2.3-14.2 months). The median follow-up period after second BNCT was 27.3 months (range, 3.8-60.4 months), and the median survival time after second BNCT was 33.6 months. The 1-year/2-year overall survival and local control after second BNCT were 81.8%/57.1% and 38.3%/22.3%, respectively. The response rates to the first and second courses of BNCT were 81.8% and 70%, respectively. Acute and late Grade 3 or higher toxicities were observed in 5 (15.1%) and 20 patients (60.6%), respectively. Only one patient developed Grade 5 aspiration pneumonia. A second course of BNCT developed a high incidence of late Grade 3 or higher toxicities with limited clinical benefit. Therefore, it may be considered only in carefully selected patients without alternative treatment options.

BACKGROUND:Boron neutron capture therapy (BNCT) is a cell-selective cancer treatment in which cancer cells are irradiated by charged particles produced by the nuclear reaction within the cells. The development of accelerator-based BNCT (AB-BNCT) has made hospital-based treatment possible, expanding its clinical applications. In AB-BNCT, epithermal neutrons penetrate tissues and slow down, with thermal neutron flux peaking at a depth of approximately 20 mm. Unlike reactor-based BNCT, which enables selection between thermal and epithermal neutron beams, AB-BNCT exclusively utilizes epithermal neutrons. Therefore, optimizing surface-dose distribution is essential for the effective treatment of superficial tumors. In conventional radiotherapy, bolus materials are used to enhance the surface dose; however, their application in BNCT remains unestablished. Although custom-made boluses, such as paraffin, hydrophilic polymer gels, and polyurethane foam, have been investigated for BNCT, their labor-intensive fabrication limits to clinical implementation. The feasibility of commercially available boluses for BNCT, particularly regarding dosimetric accuracy and activation risks, remains largely unexplored. PURPOSE:This study evaluates the feasibility of using a commercial bolus for BNCT by assessing its impact on the thermal neutron flux, gamma-dose distribution, treatment planning accuracy, and neutron-induced activation. Additionally, a quality assurance (QA) framework for the bolus materials used in BNCT is examined. METHODS:The feasibility of using a commercial bolus (Clearfit bolus, Fujidenolo Co., Ltd.) in the AB-BNCT field was evaluated using the NeuCure (Sumitomo Heavy Industries, Ltd.) system. Thermal neutron flux and gamma-dose rate distributions were measured on a water phantom, both with and without the bolus, using the gold activation method and thermoluminescent dosimeters. NeuCure Dose Engine (Sumitomo Heavy Industries, Ltd.), integrated with RayStation (RaySearch Laboratories), validated calculation accuracy. Activation analysis was conducted using a high-purity germanium detector, residual radioactivity was monitored with a Geiger-Müller (GM) counter, and dose rate variations were measured using a NaI(Tl) scintillation survey meter. RESULTS:The bolus exhibited near-water equivalence in BNCT, indicating only a slight reduction (≤3%) in peak thermal neutron flux and a parallel shift in the flux distribution. The treatment planning system accurately reproduced the measured neutron- and gamma-dose distributions when the correct bolus composition was specified. Activation analysis identified primarily short-lived radionuclides, including 11C, 13N, 15O, and 125mSn, with half-lives of 20.4, 10.0, 2.0, and 9.5 min, respectively. Residual radioactivity measurements confirmed that the GM count rate decreased to 1% of its initial value within 5 h and background levels within 2 days. The scintillation survey meter recorded background gamma-dose rates within 6 h. These findings confirm that the bolus is safe for clinical reuse following a short cooling period. CONCLUSIONS:This study is the first to comprehensively evaluate a commercially available bolus for BNCT and establish a QA framework. Three key findings demonstrate that a commercial bolus material used in radiation therapy is suitable for BNCT, offering dosimetric accuracy, precise treatment planning, and minimal activation risk. The evaluation QA framework established in this study provides basic QA items for the bolus materials used in BNCT and can be applied when introducing other new materials.

BACKGROUND:Although BNCT is a novel therapy for head and neck cancers, its efficacy in patients with oral cancer remains unclear. PATIENTS AND METHODS:Nine patients with oral cancer underwent BNCT at Southern Tohoku BNCT Research Center. We reviewed the charts and diagnostic images of these patients and analyzed their responses and adverse events associated with the therapy. RESULTS:All patients underwent surgery and/or radiotherapy as initial treatment for head and neck cancer. No patients had distant metastases at the time of BNCT. The median observation period was 16 months. Grade 3 and 4 adverse events were observed in six patients who recovered within one month. Treatment responses were complete in seven patients and partial in two. Overall survival, disease-specific survival, and local control rates of the patients at one year were 76.2, 76.2, and 87.5 %, respectively. CONCLUSION:Our study suggested that BNCT is a relatively safe and effective treatment for patients with recurrent and/or advanced oral cancer.

Markerless tumor tracking in x-ray fluoroscopic images is an important technique for achieving precise dose delivery for moving lung tumors during radiation therapy. However, accurate tumor tracking is challenging due to the poor visibility of the target tumor overlapped by other organs such as rib bones. Dual-energy (DE) x-ray fluoroscopy can enhance tracking accuracy with improved tumor visibility by suppressing bones. However, DE x-ray imaging requires special hardware, limiting its clinical use. This study presents a deep learning-based DE subtraction (DES) synthesis method to avoid hardware limitations and enhance tracking accuracy. The proposed method employs a residual U-Net model trained on a simulated DES dataset from a digital phantom to synthesize DES from single-energy (SE) fluoroscopy. Experimental results using a digital phantom showed quantitative evaluation results of synthesis quality. Also, experimental results using clinical SE fluoroscopic images of ten lung cancer patients showed improved tumor tracking accuracy using synthesized DES images, reducing errors from 1.80 to 1.68 mm on average. The tracking success rate within a 25

This study aims to evaluate the feasibility of using a commercially available boron neutron capture therapy (BNCT) dose calculation program (NeuCure® Dose Engine) in terms of calculation accuracy and computation time. Treatment planning was simulated under the following calculation parameters: 1.5–5.0 mm grid sizes and 1–10

BACKGROUND:Accelerator-based boron neutron capture therapy (AB-BNCT) systems are becoming commercially available and are expected to be widely used in hospitals. To ensure the safety of BNCT, establishing a quality assurance (QA) program and properly managing the stability of the system are necessary. In particular, a high level of beam output stability is required to avoid accidents because beam output is a major factor in patient dose. However, no studies have analyzed the long-term beam output stability of AB-BNCT systems. PURPOSE:This study aimed to retrospectively analyze the long-term stability of the beam output by statistical process control (SPC) based on the QA results over 3 years. METHODS:The data analyzed are the results of daily QA (DQA) and weekly QA (WQA) in an AB-BNCT system and were taken between June 2020 and September 2023. The evaluation of the stability of the beam output was based on the reaction rate between gold and neutrons calculated using the activation foil method using a gold foil. In DQA, which can be performed in a short time, the gold foil was applied directly to the beam irradiation aperture in air. In WQA, measurements were performed at the phantom surface, 2-cm depth, and 6-cm depth using a dedicated water phantom. The acquired data were retrospectively analyzed by individuals and a moving range chart (I-MR chart), exponentially weighted moving average control chart (EWMA chart), and several process capability indexes (PCIs). RESULTS:Over 99% of the DQA I-MR chart results were within control limits, whereas the WQA I-MR chart results showed that 1.8%, 4.1%, and 2.0% of the measurements exceeded the control limits at the surface, 2-cm depth, and 6-cm depth, respectively. The variation in the reaction rate of the gold foil before and after the replacement of the target was <0.5%. The EWMA chart results revealed no significant beam output drift for either DQA or WQA. Most measured data were normal based on the results of the Anderson-Darling test and met the requirements for PCI evaluation; most PCI values were >1.0; however, the Cpmk of DQA and the 2- and 6-cm depth WQAs between August 2021 and November 2022 in treatment course 2 were 0.83, 0.77, and 0.87, respectively, which were <1.0. CONCLUSIONS:The long-term stability of beam output was confirmed using SPC in an AB-BNCT system. The results of the control chart revealed no significant variation or drift in the beam output, and the quantitative evaluation using PCI revealed high stability. A routine QA program will enable us to provide safe BNCT.

The neutron beam in boron neutron capture therapy (BNCT) exhibits poor directionality and significantly decreasing neutron flux with increasing distance. Therefore, the treatment site must be close to the irradiation aperture. Some patients with head and neck cancer may benefit from a sitting-position setup. The study aim was to evaluate the treatment-positioning accuracy and dose error in sitting patients receiving BNCT. Thirty-two patients with head and neck cancer who underwent sitting-position BNCT at Southern Tohoku BNCT Research Center were included in the study. Horizontal (Delta X) and vertical (Delta Y) errors were defined as the displacement between the treatment planning system (TPS) digital reconstructed radiograph and the pre-treatment X-ray image. Using in-house software, image matching was performed. The beam-axial directional (Delta Z) error was compared with the parameters entered into the TPS and the actual pre-treatment measured values. The translational-position error was reflected in the TPS's patient coordinate system with respect to the reference plan. Re-dose calculations were performed to evaluate the effect of positional error on tumor and normal-tissue doses. The [Delta X, Delta Y, Delta Z] (DRR-CR) mean +/- 1SD were - 0.40 +/- 2.0, 0.30 +/- 2.3, and - 1.4 +/- 1.5 mm, respectively. The D-mean and D-98% tumor-dose errors were 1.22 % +/- 1.44 % and 0.99 % +/- 1.63 %, respectively. The D-2% pharyngeal and oral mucosal-dose errors were 0.98 % +/- 1.91 % and 1.21 % +/- 1.78 %, respectively. The tumor- and normal-tissue dose errors were typically < 5 %. High-precision treatment was feasible in sitting-positioned BNCT.

This study aimed to identify the required capabilities and workload of medical staff in accelerator-based boron neutron capture therapy (BNCT). From August to September 2022, a questionnaire related to the capabilities and workload in the accelerator-based BNCT was administered to 12 physicians, 7 medical physicists and 7 radiological technologists engaged in BNCT and 6 other medical physicists who were not engaged in BNCT to compare the results acquired by those engaged in BNCT. Only 6-21% of patients referred for BNCT received it. Furthermore, 30-75% of patients who received BNCT were treated at facilities located within their local district. The median required workload per treatment was 55 h. Considering additional workloads for ineligible patients, the required workload reached similar to 1.2 times longer than those for only eligible patients' treatment. With respect to capabilities, discrepancies were observed in treatment planning, quality assurance and quality control, and commissioning between medical physicists and radiological technologists. Furthermore, the specialized skills required by medical physicists are impossible to acquire from the experience of conventional radiotherapies as physicians engaged in BNCT were specialized not only in radiation oncology, but also in other fields. This study indicated the required workload and staff capabilities for conducting accelerator-based BNCT considering actual clinical conditions. The workload required for BNCT depends on the occupation. It is necessary to establish an educational program and certification system for the skills required to safely and effectively provide BNCT to patients.

Head and neck cancer (HNC) accounts for approximately 5% of all malignancies, and >90% of these cases are squamous cell carcinoma. The primary treatment usually comprises surgery and radiation therapy administered with or without chemotherapy. Because the head and neck region has physiological and cosmetic functions, such as respiration, vocalization, mastication, and swallowing, treatment is selected while considering the balance between curability and deterioration of the quality of life. However, few treatment options are available for recurrent HNC after standard therapy, which indicates an urgent need to develop a treatment method that can be highly curative while preserving organ function in patients with HNC. In this context, boron neutron capture therapy (BNCT) is considered to have great potential.

NeuCure & REG; is the only accelerator-based boron neutron capture therapy (BNCT) system in the world with pharmaceutical approval. Until now, only flat collimators (FCs) on the patient side have been installed. However, in some cases of head and neck cancer patients, positioning the patient close enough to the collimator when using FCs was difficult. Thus, there are concerns about the prolongation of the irradiation time and overdose to normal tissues. To address these issues, a collimator with a convex-extended section on the patient side (extended collimators [ECs]) was developed, and its pharmaceutical approval was obtained in February 2022. This study evaluated the physical characterization and usefulness of each collimator using a simple geometry water phantom model and human model. In the water phantom model, the thermal neutron fluxes at 2 cm depth on the central axis were 5.13 x 108, 6.79 x 108, 1.02 x 109, and 1.17 x 109n/cm2/s for FC(120), FC(150), EC50(120), and EC100(120), respectively, when the distance from the irradiation aperture was kept constant at 18 cm. With ECs, the relative off-axis thermal neutron flux decreased steeply. In the hypopharyngeal cancer human model, the tumor dose changes were within <2%, but the maximum oral mucosa doses were 7.79, 8.51, 6.76, and 4.57 Gy-Eq, respectively. The irradiation times were 54.3, 41.3, 29.2, and 24.8 min, respectively. In cases where positioning the patient close to the collimator is difficult, the use of ECs may reduce the dose to normal tissues and shorten the irradiation time.

Background and purpose Boron neutron capture therapy (BNCT) has been routinely practiced for treatment of head and neck cancer in Japan. However, differences in contouring the oral and pharyngeal mucosa can lead to discrepancies in treatment. This study aimed to introduce a standardized approach using an MRI-based atlas, aiming to minimize inter-observer error and improve dose precision. Materials and Methods An MRI atlas of the head and neck mucosa was developed using water/fat-separated images from a healthy man. Using CT images from three patients, seven radiation oncologists performed contouring of the head and neck mucosa twice over a 3-week period. Contouring was first performed using CT alone, then later using fused T2-weighted images with the mucosal atlas for guidance. Contouring errors were assessed and their impacts on tumor dose were evaluated. Results The introduction of the MRI-based mucosal atlas significantly reduced inter-observer variation in mucosal volume (the coefficient of variation, abbreviated with COV, decreased from 0.61 with CT alone to 0.21 with the MRI atlas; p=0.003). Moreover, the atlas resulted in improved contour homology among observers and reduced variations in tumor dose. For all cases, COVs for maximum, mean, and minimum tumor doses were all below 5%. Conclusion Utilizing an MRI-based mucosal atlas in BNCT contouring can significantly reduce inter-observer variation, improve contour homology, and decrease variations in tumor dose. These findings suggest strong potential for standardizing and enhancing the quality of BNCT for head and neck cancer.

The dosimetric effect of set-up error in boron neutron capture therapy (BNCT) for head and neck cancer remains unclear. In this study, we analyzed the tendency of dose error by treatment location when simulating the set-up error of patients. We also determined the tolerance level of the set-up error in BNCT for head and neck cancer. As a method, the distal direction was shifted with an interval of 2.5 mm, from 0.0 mm to +20.0 mm and compared with the dose at the reference position. Similarly, the horizontal direction and vertical direction were shifted, with an interval of 5.0 mm, from -20.0 mm to +20.0 mm. In addition, cases with 3.0 mm and 5.0 mm simultaneous shifts in all directions were analyzed as the worst-case scenario. The dose metrics of the minimum dose of the tumor and the maximum dose of the mucosa were evaluated. From unidirectional set-up error analysis, in most cases, the set-up errors with dose errors within +/- 5% were Delta distal < +2.5 mm, Delta horizontal < +/- 5.0 mm and Delta vertical < +/- 5.0 mm. In the simulation of 3.0 mm shifts in all directions, the errors in the minimum tumor dose and maximum mucosal dose were -3.6% +/- 1.4% (range, -5.4% to -0.6%) and 2% +/- 1.4% (range, 0.4% to 4.5%), respectively. From these results, if the set-up error was within +/- 3.0 mm in each direction, the dose errors of the tumor and mucosa could be suppressed within approximately +/- 5%, which is suggested as a tolerance level.

Abstract The purpose of this study was to outline the course and profile of adverse events specific to boron neutron capture therapy (BNCT) for head and neck cancer. This was a sub-analysis of the phase II JHN002 trial. Patients received 400 mg/kg borofalan(10B), followed by neutron irradiation. The course of adverse events after BNCT was documented in the JHN002 Look Up study. Patients were grouped into face/front (FF), face/lateral (FL) and neck (N) beam groups according to the point of skin incidence of the epithermal neutron beam axis, and the profile of adverse events dependent on beam incidence position was examined. The courses of adverse events in eight recurrent squamous cell carcinoma (R-SCC) and 13 recurrent or locally advanced non-SCC cases were analyzed. Median interval to complete recovery was 23 days (interquartile range (IQR), 14–48 days) for oral mucositis, 40 days (IQR, 24–56 days) for dermatitis, 58 days (IQR, 53–80 days) for dysgeusia and 156 days (IQR, 82–163 days) for alopecia. In the FF beam group, parotitis (P = 0.007) was less frequent, while oral mucositis (P = 0.032), fatigue (P = 0.002), conjunctivitis (P = 0.001), epistaxis (P = 0.001) and abdominal discomfort (P = 0.029) tended to be more frequent than in the FL and N beam groups. Courses and irradiation site-specific profiles of adverse events in BNCT for head and neck cancer were identified. This profile may be useful for considering interventions to prevent exacerbation of treatment-related adverse events on BNCT.

The irradiation field of boron neutron capture therapy (BNCT) consists of multiple dose components including thermal, epithermal and fast neutron, and gamma. The objective of this work was to establish a methodology of dosimetric quality assurance (QA), using the most standard and reliable measurement methods, and to determine tolerance level for each QA measurement for a commercially available accelerator-based BNCT system. In order to establish a system of dosimetric QA suitable for BNCT, the following steps were taken. First, standard measurement points based on tissue-administered doses in BNCT for brain tumors were defined, and clinical tolerances of dosimetric QA measurements were derived from the contribution to total tissue relative biological effectiveness factor-weighted dose for each dose component. Next, a QA program was proposed based on TG-142 and TG-198, and confirmed that it could be assessed whether constancy of each dose component was assured within the limits of tolerances or not by measurements of the proposed QA program. Finally, the validity of the BNCT QA program as an evaluation system was confirmed in a demonstration experiment for long-term measurement over 1 year. These results offer an easy, reliable QA method that is clinically applicable with dosimetric validity for the mixed irradiation field of accelerator-based BNCT.

Boron neutron capture therapy (BNCT) selectively kills tumor cells using the energy of alpha rays (He nuclei) and Li recoil nuclei emitted by the transmutation reaction between boron 10B and thermal neutrons. Currently, 10B-boronophenylalanine, generally named borofalan(10B), in which a boron group is attached to phenylalanine, is used as a boron agent, and is taken up into tumor cells based on increased amino acid metabolism. Depending on the tumor selectivity of this boron agent, it will produce a large dose difference from the adjacent normal cells. While the principle is clear, there are several difficulties: the physics aspect that the irradiated neutrons is not straightforward, the biology aspect that the cell response to the boron/neutron reaction is different for each cell type, and the clinical aspect that it is difficulty to assess the actual concentration of boron in the tissues, as accumulation of boron agent varies from tissue to tissue. The most significant clinical difficulty is the limited reach of neutrons into deep tissues. Therefore, the tumor conditions that can be treated effectively is limited, and in clinical practice, it is necessary not to miss the appropriate time to perform this therapy in each patient in order to utilize this therapy effectively. In this presentation, we will review the actual treatment of recurrent head and neck cancer that is currently being performed at our hospital.

We aimed to evaluate dosimetric effects of ipsilateral shoulder position variations (ISPVs) in sitting-positioned boron neutron capture therapy (BNCT) for lower neck tumor. The ISPVs were simulated using deformed shoulder images that can simulate arbitrary shape. The dose-volume parameters for the tumor in the rotated shoulder plans considerably varied compared with that for the mucosa. Even in a small number of cases, these differences were clearly observed among patients. The ISPVs in lower neck BNCT have great dosimetric effects.

Lung cancer with low average iodine density measured via contrast-enhanced computed tomography (CT) using dual-energy CT technology has shown a reduced local control rate after stereotactic body radiotherapy (SBRT). The current study therefore investigated the relationship between low iodine density tumor area and its ratio and local recurrence after SBRT. Dual-energy CT was performed on the day before SBRT initiation, with a low iodine density tumor area being defined as that with an iodine density of <1.81 mg cm(-)(3). The low iodine density tumor area, the ratio between the low iodine density tumor area and the entire tumor, and the local recurrence rate were then determined. No correlation was observed between the low iodine density tumor area and the local recurrence rate. However, tumors with a large low iodine density tumor area ratio showed an increased local recurrence rate, with the prognostic accuracy almost similar to that in previous studies using average iodine densities. Our results therefore suggest that the low iodine density tumor area ratio was a useful prognostic index after SBRT, with an accuracy comparable with that of the average iodine density.

Background and purpose: Boron neutron capture therapy (BNCT) can be performed without reactors due to development of cyclotron-based epithermal neutron source (C-BENS), which is optimized for treatment for deeper-seated tumors. The purpose of this study was to evaluate efficacy and safety of cyclotron-based BNCT with borofalan (B-10) for recurrent or locally advanced head and neck cancer. Materials and methods: In this open-label, phase II JHN002 trial of BNCT using C-BENS with borofalan (B-10), patients with recurrent squamous cell carcinoma (R-SCC) or with recurrent/locally advanced non-squamous cell carcinoma (R/LA-nSCC) of the head and neck were intravenously administered 400 mg/kg borofalan (B-10), followed by neutron irradiation. The tumor dose was determined passively as the mucosal maximum dose of 12 Gy-Eq. The primary endpoint was the objective response rate (ORR). Post-trial observational JHN002 Look Up study was planned for evaluating locoregional progression-free survival (LRPFS). Results: Eight R-SCC and 13 R/LA-nSCC patients were enrolled. All R-SCC patients had prior radiotherapy with a median dose of 65.5 Gy (range, 59.4-76.0 Gy). The ORR for all patients was 71%, and complete response/partial response were 50%/25% in R-SCC and 8%/62% in R/LA-nSCC. The 2-year overall survival for R-SCC and R/LA-nSCC were 58% and 100%, respectively. The median LRPFS was 11.5 months for R-SCC. Frequently observed adverse events included alopecia (95%), hyperamylasemia (86%), and nausea (81%). Conclusion: These data suggest that BNCT using C-BENS with borofalan (B-10) is a promising treatment option for patients with R-SCC or R/LA-nSCC of the head and neck. (C) 2020 The Authors. Published by Elsevier B.V.

2536 Background: Boron neutron capture therapy (BNCT) is tumor-selective particle radiation and theoretically efficacious especially for tumors with infiltrative nature, such as glioblastoma (GBM). The aim of this study is to assess safety and efficacy of accelerator-based BNCT (AB-BNCT) using cyclotron-based neutron generator, BNCT30, and 10 B-boronophenylalanine (borofalan( 10 B)) agent, SPM-011, in patients with recurrent malignant gliomas, chiefly GBM. Methods: The multi-institutional open-label, phase II clinical trial for recurrent 27 cases of malignant gliomas (MG) (24 cases were GBM) was conducted with above mentioned AB-BNCT system, using 500mg/kg of SPM-011 (study code, JG002). The patients were enrolled from February 2016 to June 2018. The inclusion criteria are bevacizumab-naïve MG, recurrent after standard treatment composed of XRT and chemotherapy with TMZ. Neutron-irradiation time were determined not to exceed to 8.5 Gy-Eq for scalp dose which was decided by preceding phase I trial. Primary endpoint was 1-year survival rate and secondary ones were median overall survival (mOS), median progression free survival (mPFS) and so on. The results were compared to previous Japanese domestic bevacizumab trial for recurrent GBM (JO22506) which had the similar inclusion criteria with JG002. Results: 1-year survival rate and mOS of recurrent GBM cases in JG002 was 79.2% (95% CI:57.0-90.8) and 18.7 months (95% CI:12.9-23.4) (data cutoff = 20 Jun 2019) respectively, while those of JO22506 was 34.5% (90% CI:20.0-49.0) and 10.5 months (95% CI:8.2-12.4), respectively. Median PFS of JG002 and JO22506 were 0.9 and 3.3 months, respectively. Most important adverse event in JG002 was brain edema. 21 out of 27 cases were treated with bevacizumab after progress disease. Conclusions: AB-BNCT demonstrated acceptable safety and prolonged survival for recurrent MG chiefly GBM. AB-BNCT might produce brain edema somewhat after the treatment, which might be the unavoidable adverse event of re-irradiation for recurrent MG, however that seemed to be controlled with bevacizumab. Clinical trial information: JapicCTI-194742 . [Table: see text]