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Background and Purpose: Definitive radiotherapy for patients with scalp angiosarcoma has a poor prognosis, often resulting in severe skin adverse events. Additionally, malignant melanoma is known for its radioresistant nature. Boron neutron capture therapy (BNCT) may address these challenges due to the high uptake capacity of boron drugs in these cancer types. We aimed to determine the treatment dose for BNCT and evaluate the incidence of acute adverse events AEs following BNCT in patients with primary or recurrent angiosarcoma/malignant melanoma of the skin., Materials and Methods: This was a single-center, non-randomized clinical trial with a three-step dose escalation plan, involving maximum skin doses of 12, 15, and 18 Gy-Eq following a 3 + 3 design. The patients underwent BNCT between November 2019 and April 2022. The primary endpoint was to evaluate the incidence of acute adverse events., Results: Ten patients (scalp angiosarcomanine, forefinger malignant melanoma: one) were included. The median target lesion size was 46.5 (range: 20-145) mm. A transient asymptomatic increase in serum amylase level was the only grade 3 adverse event. The best overall response rate within 180 days was 70 % (median tumor shrinkage rate: 77.5 % [4.9-100 %])., Conclusions: BNCT with a dose of 18 Gy-Eq is a feasible treatment option, demonstrating a favorable safety profile and a high response rate in patients with primary or recurrent angiosarcoma or malignant melanoma of the skin., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: [Dr. Kashihara reports lecture fees from AstraZeneca and HIMEDIC, Inc. outside the submitted manuscript. Dr. Igaki reports honoraria and a research grant from Cancer Intelligence Care Systems, Inc. and HIMEDIC, Inc. outside the submitted manuscript. Dr. Nakamura received a research grant from Cancer Intelligence Care Systems, Inc. The authors declare that they have no competing financial interests or personal relationships that could have influenced the work reported in this study]., (Copyright © 2024 The Author(s). Published by Elsevier B.V. All rights reserved.)

Purpose: The normal brain is an important dose-limiting organ for brain cancer patients undergoing radiotherapy. This study aims to develop a model to calculate photon isoeffective doses (D IsoE ) to normal brain that can explain the incidence of grade 2 or higher somnolence syndrome (SS⩾2) after Boron Neutron Capture Therapy (BNCT)., Methods: A D IsoE model was constructed to find the reference photon dose that equals the Normal Tissue Complication Probability (NTCP) of the absorbed dose from BNCT. Limb paralysis rates from the rat spinal cord model exposed to conventional or BNCT irradiation were used to determine model parameters. NTCP expressions for both irradiations were constructed based on Lyman's model accordingly. D IsoE values were calculated for BNCT treatments performed in Finland and USA. An equivalent uniform dose (EUD) based on peak and average whole-brain doses and treatment fields was also introduced. Combining D IsoE and EUD models, a dose-response curve for SS⩾2 in BNCT patients was constructed and compared to conventional radiotherapy outcomes., Results: The D IsoE model reveals higher than expected photon-equivalent doses in the brain, indicating the need to modify standard dose calculation methods. Neither peak dose nor average whole-brain dose alone predicts SS⩾2 development. However, the dose-response curve derived from combining D IsoE and EUD models effectively explains the incidence of SS⩾2 after BNCT., Conclusions: The introduced D IsoE and EUD models predict the incidence of somnolence syndrome after BNCT. The first dose-response relationship for SS⩾2 derived entirely from brain tumour patients treated with BNCT, consistent with photon radiotherapy responses, is presented., Competing Interests: Declaration of competing interest None, (Copyright © 2024. Published by Elsevier Ltd.)

Background and Purpose: Head and neck cancer patients undergoing boron neutron capture therapy (BNCT) often experience BNCT-induced nausea and vomiting (BINV). This study aimed to construct a BINV risk prediction model., Materials and Methods: In this retrospective study, 237 patients were randomly divided into a training and test cohort. In the training cohort, a univariate analysis was performed to identify factors associated with BINV. Multivariate analysis was used to identify factors and calculate coefficients for the model. The Hosmer-Lemeshow test was used to assess the goodness of fit, and receiver operating characteristic curves were plotted to evaluate the accuracy of the model. For both the training and test cohort, the predictive model was used to generate the scores and calculate the sensitivity and specificity., Results: The incidence of nausea and vomiting was 50% and 18%, respectively. Female sex, younger age, non-squamous cell carcinoma, no prior chemotherapy, and beam entry from the face/lateral region were associated with the occurrence of BINV. The prediction model showed a good fit (P = 0.96) and performance (area under the curve = 0.75). The sensitivity and specificity were 83% and45 % for the training cohort (n = 193) and 86% and 59% for the test cohort (n = 44), respectively., Conclusion: We developed a simple model that predicts BINV. This will enable appropriate care to be implemented based on increased risk to prevent its occurrence., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: K.H. reports personal research funding from Stella Pharma Corporation., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The role of external beam radiotherapy (EBRT) in thyroid cancer (TC) remains contentious due to limited data. Retrospective studies suggest adjuvant EBRT benefits high-risk differentiated thyroid cancer (DTC) and limited-stage anaplastic thyroid carcinoma (ATC), enhancing locoregional control and progression-free survival when combined with surgery and chemotherapy. Intensity-modulated radiotherapy (IMRT) and particle therapy (PT), including protons, carbon ions, and Boron Neutron Capture Therapy (BNCT), represent advances in TC treatment. Following PRISMA guidelines, we reviewed 471 studies from January 2002 to January 2024, selecting 14 articles (10 preclinical, 4 clinical). Preclinical research focused on BNCT in ATC mouse models, showing promising local control rates. Clinical studies explored proton, neutron, or photon radiotherapy, reporting favorable outcomes and manageable toxicity. While PT shows promise supported by biological rationale, further research is necessary to clarify its role and potential combination with systemic treatments in TC management., Competing Interests: Declaration of Competing Interest None declared, (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background and Purpose: Patients with hypopharyngeal cancer (HPC)/laryngeal cancer (LCA) with a history of head and neck irradiation are often difficult to treat with conventional radiotherapy. This study aimed to clarify the efficacy and safety of boron neutron capture therapy (BNCT) for HPC/LCA., Materials and Methods: In this retrospective study, HPC/LCA with local lesions were analyzed, including both recurrent cases after treatment and second primary cases. The primary endpoints were tumor response and incidence of adverse events (AEs) after BNCT. The secondary endpoints were local control (LC), progression-free survival (PFS), and overall survival (OS). Evaluation of tumor response was terminated when any additional treatment was administered, and only survival data were collected., Results: The analysis included 25 and 11 cases of HPC and LCA, respectively. All had a history of head and neck irradiation, and median dose of prior radiotherapy was 70 Gy. The complete response (CR) rate was 72%, overall response rate was 84%, and the 1-year LC and PFS were 63.1% and 53.7%, respectively. The median survival time was 15.5 months, and the 2-year OS was 79.8%. Of the 27 patients with CR, 11 cases recurred at a median of 6.0 months. The acute G3 AEs were oral mucositis (6%), pharyngeal mucositis (3%), and soft tissue infection (3%). Acutely, there were no G4-5 AEs, except hyperamylasemia, and in the late phase, there were no G3 or higher AEs., Conclusion: BNCT can be achieve good tumor response while preserving the larynx without severe AEs., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: KH has received personal research funding from Stella Pharma Corporation., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Purpose: Pediatric diffuse malignant glioma located in the brainstem was officially named "diffuse midline glioma" (DMG) by the World Health Organization in 2016. For this disease, radical surgery is not beneficial, and the only major treatment strategy is radiotherapy. However, the dose limitations to brainstem tissue mean that treatment by radiotherapy can only control and not eradicate the tumors, and there is no effective treatment for recurrence, resulting in short overall survival of 6-12 months. This paper reports our experience with boron neutron capture therapy (BNCT), a new treatment process, and its efficacy in treating children with recurrent DMG., Methods: From September 2019 to July 2022, we treated 6 children affected by recurrent DMG. With the collaboration of Taipei Veteran General Hospital (TVGH) and National Tsing-Hua University (NTHU), each patient received two sessions of BNCT within 1 month., Results: Among the six patients, three showed partial response and the rest had stable disease after the treatment. The overall survival and recurrence-free survival duration after treatment were 6.39 and 4.35 months, respectively. None of the patients developed severe side effects, and only one patient developed brain necrosis, which was most likely resulted from previous hypofractionated radiotherapy received., Conclusion: BNCT elicited sufficient tumor response with low normal tissue toxicity; it may benefit vulnerable pediatric patients with DMG., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Radiation-induced liver diseases, including liver fibrosis, occurs when radiation damages the liver. Basic research on hepatic fibrosis, which is a late radiation injury, is necessary for evaluating adverse liver events occurring after boron neutron capture therapy. This study was conducted to establish a method for analyzing the negative effect such as fibrosis in the liver tissue after boron neutron capture therapy. Female C57BL6 mice were injected with p-boronophenylalanine solution subcutaneously at 2 h before neutron irradiation. Masson trichrome staining was performed to determine the degree of liver fibrosis. The degree of fat accumulation in mouse normal liver tissue after boron neutron capture therapy was evaluated using hematoxylin and eosin staining and triglyceride quantification. Western blotting was performed to determine the expression level of Sonic Hedgehog. Liver fat accumulation and fibrosis were significantly increased in the neutron irradiation group injected with p-boronophenylalanine compared with control group. In addition, Sonic Hedgehog expression was increased in response to boron neutron capture therapy-induced liver injury and was involved in liver fibrosis. Hepatocellular fat accumulation and Hedgehog signaling activation may be indicators of adverse events related to boron neutron capture therapy associated with liver fibrosis., (©2022 by Radiation Research Society. All rights of reproduction in any form reserved.)

Local recurrence of colorectal cancer (CRC) can occur in patients after curative resection, and additional surgical resection may therefore be required; however, this is a significant burden for patients, because additional surgical resection may necessitate the resection of other organs such as the bladder, prostate, uterus, or sacral bone. Therefore, there is a need for alternative therapeutic strategies. We focused on boron neutron capture therapy (BNCT) as a treatment modality that can selectively target tumor cells without excessive damage to normal tissues. The usefulness of BNCT to pelvic CRC remains unknown. This study investigated the anti-cancer effect of boronophenylalanine (BPA)-mediated BNCT in a previously established mouse model of pelvic recurrence of CRC. Uptake of BPA in CRC was observed both in vitro and in vivo, and the concentrations were sufficient for BNCT. Our results are the first to show that BPA-mediated BNCT prolonged the survival of experimental mice with pelvic tumors; moreover, it did not cause any obvious severe side effects in the treated animals. In conclusion, BPA-mediated BNCT could contribute to treating local recurrence of pelvic CRC., Competing Interests: Conflict of interest statement The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Masashi Yamamoto reports financial support was provided by Japan society for the promotion of science., (Copyright © 2022 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

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 Author(s) 2022. Published by Oxford University Press on behalf of The Japanese Radiation Research Society and Japanese Society for Radiation Oncology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Background: Although boron neutron capture therapy has shown excellent survival data, previous studies have shown an increase in radiation necrosis against recurrent malignant glioma. Herein, we proposed that bevacizumab may reduce radiation injury from boron neutron capture therapy by re-irradiation. We evaluated the efficacy and safety of a boron neutron capture therapy and add-on bevacizumab combination therapy in patients with recurrent malignant glioma., Methods: Patients with recurrent malignant glioma were treated with reactor-based boron neutron capture therapy. Treatment with bevacizumab (10 mg/kg) was initiated 1-4 weeks after boron neutron capture therapy and was administered every 2-3 weeks until disease progression. Initially diagnosed glioblastomas were categorized as primary glioblastoma, whereas other forms of malignant glioma were categorized as non-primary glioblastoma., Results: Twenty-five patients (14 with primary glioblastoma and 11 with non-primary glioblastoma) were treated with boron neutron capture therapy and add-on bevacizumab. The 1-year survival rate for primary glioblastoma and non-primary glioblastoma was 63.5% (95% confidence interval: 33.1-83.0) and 81.8% (95% confidence interval: 44.7-95.1), respectively. The median overall survival was 21.4 months (95% confidence interval: 7.0-36.7) and 73.6 months (95% confidence interval: 11.4-77.2) for primary glioblastoma and non-primary glioblastoma, respectively. The median progression-free survival was 8.3 months (95% confidence interval: 4.2-12.1) and 15.6 months (95% confidence interval: 3.1-29.8) for primary glioblastoma and non-primary glioblastoma, respectively. Neither pseudoprogression nor radiation necrosis were identified during bevacizumab treatment. Alopecia occurred in all patients. Six patients experienced adverse events ≥grade 3., Conclusions: Boron neutron capture therapy and add-on bevacizumab provided a long overall survival and a long progression-free survival in recurrent malignant glioma compared with previous studies on boron neutron capture therapy alone. The add-on bevacizumab may reduce the detrimental effects of boron neutron capture therapy, including pseudoprogression and radiation necrosis. Further studies of the combination therapy with a larger sample size and a randomized controlled design are warranted., (© The Author(s) 2022. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Boron neutron capture therapy (BNCT) is a targeted therapy, which consists of preferential accumulation of boron carriers in tumor followed by neutron irradiation. Each oral cancer patient has different risks of developing one or more carcinomas and/or oral mucositis induced after treatment. Our group proposed the hamster oral cancer model to study the efficacy of BNCT and associated mucositis. Translational studies are essential to the advancement of novel boron delivery agents and targeted strategies. Herein, we review our work in the hamster model in which we studied BNCT induced mucositis using three different cancerization protocols, mimicking three different clinical scenarios. The BNCT-induced mucositis increases with the aggressiveness of the carcinogenesis protocol employed, suggesting that the study of different oral cancer patient scenarios would help to develop personalized therapies.

Purpose: Boron neutron capture therapy (BNCT) combines selective accumulation of 10 B carriers in tumor tissue with subsequent neutron irradiation. BNCT has been proposed for the treatment of multiple, non-resectable, diffuse tumors in lung. The aim of the present study was to evaluate the therapeutic efficacy and toxicity of BNCT in an experimental model of lung metastases of colon carcinoma in BDIX rats and perform complementary survival studies., Materials and Methods: We evaluated tumor control and toxicity in lung 2 weeks post-BNCT at 2 dose levels, including 5 experimental groups per dose level: T0 (euthanized pre-treatment), Boronophenylalanine-BNCT (BPA-BNCT), BPA + Sodium decahydrodecaborate-BNCT ((BPA + GB-10)-BNCT), Beam only (BO) and Sham (no treatment, same manipulation). Tumor response was assessed employing macroscopic and microscopic end-points. An additional experiment was performed to evaluate survival and oxygen saturation in blood., Results and Conclusions: No dose-limiting signs of short/medium-term toxicity were observed in lung. All end-points revealed statistically significant BNCT-induced tumor control vs Sham at both dose levels. The survival experiment showed a statistically significant 45% increase in post-treatment survival time in the BNCT group (48 days) versus Sham (33 days). These data consistently revealed growth suppression of lung metastases by BNCT with no manifest lung toxicity. Highlights Boron Neutron Capture Therapy suppresses growth of experimental lung metastases No BNCT-induced short/medium-term toxicity in lung is associated with tumor control Boron Neutron Capture Therapy increased post-treatment survival time by 45.

In boron neutron capture therapy, it is important to evaluate the dose administered to a patient's body outside the tumour area. The exposure dose is evaluated by calculation; however, the calculated value must be validated using a measured value. The dose evaluations based on the measured neutron spectrum are investigated. Multi-foil activation, combined with a LiCaAlF 6 scintillation detector and an imaging plate, is proposed as a measurement method. The proposed method can measure the neutron spectrum at various points quickly., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Aim: Determination of boron neutron capture therapy in-phantom parameters by response matrix (RM) method., Materials and Methods: In this study, various in-phantom figures-of-merit including therapeutic gain, advantage depth dose rate, advantage depth, therapeutic depth, treatment time, skin dose rate, and skull dose rate have been analyzed using the RM method. This method is based on the division of neutron/gamma spectrum and calculation of various dose components of each energy group. Summation of these dose responses is equal to the total dose of the whole spectrum. Based on this method, in-phantom parameters could be calculated by a computer program in a very short time., Results: There is a good agreement between direct calculation and RM method. The maximum allowable contaminations of the thermal and fast neutrons in a neutron beam have been calculated by RM method. It was found that these values are 17.4% and 2.6%, for thermal and fast neutron, respectively., Conclusion: The results confirm that the RM method is a fast method to evaluate in-phantom parameters without repeating simulations due to change in neutron spectrum and treatment conditions., Competing Interests: There are no conflicts of interest

Boron neutron capture therapy (BNCT) is a promising modality for biochemically targeted, highly selective radiation treatment of various cancers, including malignant gliomas. Currently available results demonstrate the beneficial effect of such therapy on survival of patients with both recurrent and newly diagnosed glioblastomas. The main drawback of BNCT in cases of previously irradiated neoplasms is high rates of symptomatic pseudoprogression and radiation necrosis. For prevention of these complications, concurrent administration of bevacizumab may be helpful. Further studies are needed to establish the optimal therapeutic protocols and to define the exact role of this management option in multimodality treatment strategies. Recent technological developments of accelerator-based neutron sources may simplify placement of the device for BNCT within clinical facilities and lead to wider application of this technique in cases of various cancers., (© 2018 S. Karger AG, Basel.)

Boron neutron capture therapy (BNCT) is based on selective accumulation of B-10 carriers in tumor followed by neutron irradiation. We demonstrated, in 2001, the therapeutic effect of BNCT mediated by BPA (boronophenylalanine) in the hamster cheek pouch model of oral cancer, at the RA-6 nuclear reactor. Between 2007 and 2011, the RA-6 was upgraded, leading to an improvement in the performance of the BNCT beam (B2 configuration). Our aim was to evaluate BPA-BNCT radiotoxicity and tumor control in the hamster cheek pouch model of oral cancer at the new "B2" configuration. We also evaluated, for the first time in the oral cancer model, the radioprotective effect of histamine against mucositis in precancerous tissue as the dose-limiting tissue. Cancerized pouches were exposed to: BPA-BNCT; BPA-BNCT + histamine; BO: Beam only; BO + histamine; CONTROL: cancerized, no-treatment. BNCT induced severe mucositis, with an incidence that was slightly higher than in "B1" experiments (86 vs 67%, respectively). BO induced low/moderate mucositis. Histamine slightly reduced the incidence of severe mucositis induced by BPA-BNCT (75 vs 86%) and prevented mucositis altogether in BO animals. Tumor overall response was significantly higher in BNCT (94-96%) than in control (16%) and BO groups (9-38%), and did not differ significantly from the "B1" results (91%). Histamine did not compromise BNCT therapeutic efficacy. BNCT radiotoxicity and therapeutic effect at the B1 and B2 configurations of RA-6 were consistent. Histamine slightly reduced mucositis in precancerous tissue even in this overly aggressive oral cancer model, without compromising tumor control.

Rheumatoid arthritis is a chronic autoimmune pathology characterized by the proliferation and inflammation of the synovium. Boron neutron capture synovectomy (BNCS), a binary treatment modality that combines the preferential incorporation of boron carriers to target tissue and neutron irradiation, was proposed to treat the pathological synovium in arthritis. In a previous biodistribution study, we showed the incorporation of therapeutically useful boron concentrations to the pathological synovium in a model of antigen-induced arthritis (AIA) in rabbits, employing two boron compounds approved for their use in humans, i.e., decahydrodecaborate (GB-10) and boronophenylalanine (BPA). The aim of the present study was to perform low-dose BNCS studies at the RA-1 Nuclear Reactor in the same model. Neutron irradiation was performed post intra-articular administration of BPA or GB-10 to deliver 2.4 or 3.9 Gy, respectively, to synovium (BNCS-AIA). AIA and healthy animals (no AIA) were used as controls. The animals were followed clinically for 2 months. At that time, biochemical, magnetic resonance imaging (MRI) and histological studies were performed. BNCS-AIA animals did not show any toxic effects, swelling or pain on palpation. In BNCS-AIA, the post-treatment levels of TNF-α decreased in four of six rabbits and IFN-γ levels decreased in five of six rabbits. In all cases, MRI images of the knee joint in BNCS-AIA resembled those of no AIA, with no necrosis or periarticular effusion. Synovial membranes of BNCS-AIA were histologically similar to no AIA. BPA-BNCS and GB-10-BNCS, even at low doses, would be therapeutically useful for the local treatment of rheumatoid arthritis.

A boron delivery system with high therapeutic efficiency and low adverse effects is crucial for a successful boron neutron capture therapy (BNCT). In this study, we developed boron cluster-containing redox nanoparticles (BNPs) via polyion complex (PIC) formation, using a newly synthesized poly(ethylene glycol)-polyanion (PEG-polyanion, possessing a (10)B-enriched boron cluster as a side chain of one of its segments) and PEG-polycation (possessing a reactive oxygen species (ROS) scavenger as a side chain of one of its segments). The BNPs exhibited high colloidal stability, selective uptake in tumor cells, specific accumulation, and long retention in tumor tissue and ROS scavenging ability. After thermal neutron irradiation, significant suppression of tumor growth was observed in the BNP-treated group, with only 5-ppm (10)B in tumor tissues, whereas at least 20-ppm (10)B is generally required for low molecular weight (LMW) (10)B agents. In addition, increased leukocyte levels were observed in the LMW (10)B agent-treated group after thermal neutron irradiation, and not in BNP-treated group, which might be attributed to its ROS scavenging ability. No visual metastasis of tumor cells to other organs was observed 1 month after irradiation in the BNP-treated group. These results suggest that BNPs are promising for enhancing the BNCT performance., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Purpose: To investigate the safety and efficacy of boron neutron capture therapy (BNCT) as a larynx-preserving treatment option for patients with recurrent laryngeal cancer., Methods and Materials: Six patients with locally recurrent squamous cell laryngeal carcinoma and 3 patients with persistent laryngeal cancer after prior treatment were treated with BNCT at the FiR1 facility (Espoo, Finland) in 2006 to 2012. The patients had received prior radiation therapy with or without concomitant chemotherapy to a cumulative median dose of 66 Gy. The median tumor diameter was 2.9 cm (range, 1.4-10.9 cm) before BNCT. Boron neutron capture therapy was offered on a compassionate basis to patients who either refused laryngectomy (n=7) or had an inoperable tumor (n=2). Boronophenylalanine-fructose (400 mg/kg) was used as the boron carrier and was infused over 2 hours intravenously before neutron irradiation., Results: Six patients received BNCT once and 3 twice. The estimated average gross tumor volume dose ranged from 22 to 38 Gy (W) (mean; 29 Gy [W]). Six of the 8 evaluable patients responded to BNCT; 2 achieved complete and 4 partial response. One patient died early and was not evaluable for response. Most common side effects were stomatitis, fatigue, and oral pain. No life-threatening or grade 4 toxicity was observed. The median time to progression within the target volume was 6.6 months, and the median overall survival time 13.3 months after BNCT. One patient with complete response is alive and disease-free with a functioning larynx 60 months after BNCT., Conclusions: Boron neutron capture therapy given after prior external beam radiation therapy is well tolerated. Most patients responded to BNCT, but long-term survival with larynx preservation was infrequent owing to cancer progression. Selected patients with recurrent laryngeal cancer may benefit from BNCT., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Purpose: To investigate the efficacy and safety of fractionated boron neutron capture therapy (BNCT) for recurrent head and neck (H&N) cancer after photon radiation therapy., Methods and Materials: In this prospective phase 1/2 trial, 2-fraction BNCT with intravenous L-boronophenylalanine (L-BPA, 400 mg/kg) was administered at a 28-day interval. Before each fraction, fluorine-18-labeled-BPA-positron emission tomography was conducted to determine the tumor/normal tissue ratio of an individual tumor. The prescription dose (D80) of 20 Gy-Eq per fraction was selected to cover 80% of the gross tumor volume by using a dose volume histogram, while minimizing the volume of oral mucosa receiving >10 Gy-Eq. Tumor responses and adverse effects were assessed using the Response Evaluation Criteria in Solid Tumors v1.1 and the Common Terminology Criteria for Adverse Events v3.0, respectively., Results: Seventeen patients with a previous cumulative radiation dose of 63-165 Gy were enrolled. All but 2 participants received 2 fractions of BNCT. The median tumor/normal tissue ratio was 3.4 for the first fraction and 2.5 for the second, whereas the median D80 for the first and second fraction was 19.8 and 14.6 Gy-Eq, respectively. After a median follow-up period of 19.7 months (range, 5.2-52 mo), 6 participants exhibited a complete response and 6 exhibited a partial response. Regarding acute toxicity, 5 participants showed grade 3 mucositis and 1 participant showed grade 4 laryngeal edema and carotid hemorrhage. Regarding late toxicity, 2 participants exhibited grade 3 cranial neuropathy. Four of six participants (67%) receiving total D80 > 40 Gy-Eq had a complete response. Two-year overall survival was 47%. Two-year locoregional control was 28%., Conclusions: Our results suggested that 2-fraction BNCT with adaptive dose prescription was effective and safe in locally recurrent H&N cancer. Modifications to our protocol may yield more satisfactory results in the future., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Boron neutron capture therapy (BNCT) is a particle radiation therapy that involves the use of a thermal or epithermal neutron beam in combination with a boron ((10)B)-containing compound that specifically accumulates in tumor. (10)B captures neutrons and the resultant fission reaction produces an alpha ((4)He) particle and a recoiled lithium nucleus ((7)Li). These particles have the characteristics of high linear energy transfer (LET) radiation and therefore have marked biological effects. High-LET radiation is a potent inducer of DNA damage, specifically of DNA double-strand breaks (DSBs). The aim of the present study was to clarify the role of DNA ligase IV, a key player in the non-homologous end-joining repair pathway, in the repair of BNCT-induced DSBs. We analyzed the cellular sensitivity of the mouse embryonic fibroblast cell lines Lig4-/- p53-/- and Lig4+/+ p53-/- to irradiation using a thermal neutron beam in the presence or absence of (10)B-para-boronophenylalanine (BPA). The Lig4-/- p53-/- cell line had a higher sensitivity than the Lig4+/+ p53-/-cell line to irradiation with the beam alone or the beam in combination with BPA. In BNCT (with BPA), both cell lines exhibited a reduction of the 50 % survival dose (D 50) by a factor of 1.4 compared with gamma-ray and neutron mixed beam (without BPA). Although it was found that (10)B uptake was higher in the Lig4+/+ p53-/- than in the Lig4-/- p53-/- cell line, the latter showed higher sensitivity than the former, even when compared at an equivalent (10)B concentration. These results indicate that BNCT-induced DNA damage is partially repaired using DNA ligase IV.

Boron neutron capture therapy (BNCT) is high linear energy transfer (LET) radiation and tumor-selective radiation that does not cause serious damage to the surrounding normal tissues. BNCT might be effective and safe in patients with inoperable, locally advanced head and neck cancers, even those that recur at previously irradiated sites. However, carotid blowout syndrome (CBS) is a lethal complication resulting from malignant invasion of the carotid artery (CA); thus, the risk of CBS should be carefully assessed in patients with risk factors for CBS after BNCT. Thirty-three patients in our institution who underwent BNCT were analyzed. Two patients developed CBS and experienced widespread skin invasion and recurrence close to the carotid artery after irradiation. Careful attention should be paid to the occurrence of CBS if the tumor is located adjacent to the carotid artery. The presence of skin invasion from recurrent lesions after irradiation is an ominous sign of CBS onset and lethal consequences., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Of the 180 patients with malignant brain tumors whom we treated with boron neutron capture therapy (BNCT) since 1968, only one (0.56%) developed multiple radiation-induced meningiomas. The parasagittal meningioma that had received 42 Gy (w) for BNCT showed more rapid growth on Gd-enhanced MRI scans and more atypical features on histopathologic studies than the temporal convexity tumor that had received 20 Gy (w). Long-term follow up MRI studies are necessary in long-survivors of malignant brain tumors treated by BNCT., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Localized dose delivery techniques to establish a brain radiation necrosis model are described. An irradiation field was designed by using accelerated protons or helium ions with a spread-out Bragg peak. Measurement of the designed field confirmed that a high dose can be confined to a local volume of an animal brain. The irradiation techniques described here are very useful for establishing a necrosis model without existence of extraneous complications., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Objectives: Searching for more effective and selective therapies for head and neck cancer, we demonstrated the therapeutic effect of boron neutron capture therapy (BNCT) to treat oral cancer and inhibit long-term tumor development from field-cancerized tissue in the hamster cheek pouch model. However, BNCT-induced mucositis in field-cancerized tissue was dose limiting. In a clinical scenario, oral mucositis affects patients' treatment and quality of life. Our aim was to evaluate different radioprotectors, seeking to reduce the incidence of BNCT-induced severe mucositis in field-cancerized tissue., Materials and Methods: Cancerized pouches treated with BNCT mediated by boronophenylalanine at 5 Gy were treated as follows: control: saline solution; Hishigh : histamine 5 mg kg(-1) ; Hislow : histamine 1 mg kg(-1) ; and JNJ7777120: 10 mg kg(-1)., Results: Hislow reduced the incidence of severe mucositis in field-cancerized tissue to 17% vs, Control: 55%; Hishigh : 67%; JNJ7777120: 57%. Hislow was non-toxic and did not compromise the long-term therapeutic effect of BNCT or alter gross boron concentration., Conclusion: Histamine reduces BNCT-induced mucositis in experimental oral precancer without jeopardizing therapeutic efficacy. The fact that both histamine and boronophenylalanine are approved for use in humans bridges the gap between experimental work and potential clinical application to reduce BNCT-induced radiotoxicity in patients with head and neck cancer., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

High-energy neutrons, named fast neutrons which have a number of undesirable biological effects on tissue, are a challenging problem in beam designing for Boron Neutron Capture Therapy, BNCT. In spite of this fact, there is not a widely accepted criterion to guide the beam designer to determine the appropriate contribution of fast neutrons in the spectrum. Although a number of researchers have proposed a target value for the ratio of fast neutron flux to epithermal neutron flux, it can be shown that this criterion may not provide the optimum treatment condition. This simulation study deals with the determination of the optimum contribution of fast neutron flux in the beam for BNCT of deep-seated tumors. Since the dose due to these high-energy neutrons damages shallow tissues, delivered dose to skin is considered as a measure for determining the acceptability of the designed beam. To serve this purpose, various beam shaping assemblies that result in different contribution of fast neutron flux are designed. The performances of the neutron beams corresponding to such configurations are assessed in a simulated head phantom. It is shown that the previously used criterion, which suggests a limit value for the contribution of fast neutrons in beam, does not necessarily provide the optimum condition. Accordingly, it is important to specify other complementary limits considering the energy of fast neutrons. By analyzing various neutron spectra, two limits on fast neutron flux are proposed and their validity is investigated. The results show that considering these limits together with the widely accepted IAEA criteria makes it possible to have a more realistic assessment of sufficiency of the designed beam. Satisfying these criteria not only leads to reduction of delivered dose to skin, but also increases the advantage depth in tissue and delivered dose to tumor during the treatment time. The Monte Carlo Code, MCNP-X, is used to perform these simulations., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The application of boron neutron capture therapy (BNCT) mediated by liposomes containing (10)B-enriched polyhedral borane and carborane derivatives for the treatment of head and neck cancer in the hamster cheek pouch oral cancer model is presented. These liposomes are composed of an equimolar ratio of cholesterol and 1,2-distearoyl-sn-glycero-3-phosphocholine, incorporating K[nido-7-CH3(CH2)15-7,8-C2B9H11] (MAC) in the bilayer membrane while encapsulating the hydrophilic species Na3[ae-B20H17NH3] (TAC) in the aqueous core. Unilamellar liposomes with a mean diameter of 83 nm were administered i.v. in hamsters. After 48 h, the boron concentration in tumors was 67 ± 16 ppm whereas the precancerous tissue contained 11 ± 6 ppm, and the tumor/normal pouch tissue boron concentration ratio was 10:1. Neutron irradiation giving a 5-Gy dose to precancerous tissue (corresponding to 21 Gy in tumor) resulted in an overall tumor response (OR) of 70% after a 4-wk posttreatment period. In contrast, the beam-only protocol gave an OR rate of only 28%. Once-repeated BNCT treatment with readministration of liposomes at an interval of 4, 6, or 8 wk resulted in OR rates of 70-88%, of which the complete response ranged from 37% to 52%. Because of the good therapeutic outcome, it was possible to extend the follow-up of BNCT treatment groups to 16 wk after the first treatment. No radiotoxicity to normal tissue was observed. A salient advantage of these liposomes was that only mild mucositis was observed in dose-limiting precancerous tissue with a sustained tumor response of 70-88%.

The potential of boron-containing lipids with three different structures, which were intended for use in boron neutron capture therapy, was investigated. All three types of boron lipids contained the anionic dodecaborate cluster as the headgroup. Their effects on two different tumor models in mice following intravenous injection were tested; for this, liposomes with boron lipid, distearoyl phosphatidylcholine, and cholesterol as helper lipids, and containing a polyethylene glycol lipid for steric protection, were administered intravenously into tumor-bearing mice (C3H mice for SCCVII squamous cell carcinoma and BALB/c mice for CT26/WT colon carcinoma). With the exception of one lipid (B-THF-14), the lipids were well tolerated, and no other animal was lost due to systemic toxicity. The lipid which led to death was not found to be much more toxic in cell culture than the other boron lipids. All of the lipids that were well tolerated showed hemorrhage in both tumor models within a few hours after administration. The hemorrhage could be seen by in vivo magnetic resonance and histology, and was found to occur within a few hours. The degree of hemorrhage depended on the amount of boron administered and on the tumor model. The observed unwanted effect of the lipids precludes their use in boron neutron capture therapy.

The therapeutic effect of surgery and/or combination of conventional chemoradiotherapy is limited in the patients with recurrent squamous cell carcinoma (SCC) and locally advanced non-squamous cell carcinoma without malignant melanoma (non-SCC) of the head and neck. Currently, clinical trials of BNCT for head and neck cancers are being conducted in some institutes to verify its the effectiveness. BNCT was performed in 10 patients with recurrent SCC, 7 patients with recurrent non-SCC and 3 patients with newly diagnosed non-SCC in our university between October 2003 and September 2007. Eleven patients showed complete remission and 7 patients showed partial remission of irradiated site. The effective rate [(CR+PR)/total cases] was 90%. No severe acute or chronic normal-tissue reactions were observed in any patients. BNCT is effective and safe in the patients with recurrent SCC and locally advanced non-SCC., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

To introduce our experience of treating locally and regionally recurrent head and neck cancer patients with BNCT at Tsing Hua Open-Pool Reactor in Taiwan, 12 patients (M/F=10/2, median age 55.5 Y/O) were enrolled and 11 received two fractions of treatment. Fractionated BNCT at 30-day interval with adaptive planning according to changed T/N ratios was feasible, effective and safe for selected recurrent head and neck cancer in this trial., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Purpose: Boron neutron capture therapy (BNCT) is among the radiation treatments known to have a selective lethal effect on tumor cells. This study summarizes the tumor responses and the acute and late adverse effects of BNCT in the treatment of patients with both recurrent and newly diagnosed T4 salivary gland carcinoma., Methods: Two patients with recurrent cancer and 3 with newly diagnosed T4 advanced malignancy were registered between October 2003 and September 2007, with the approval of the medical ethics committees of Kawasaki Medical School and Kyoto University. BNCT was performed, in a single fraction using an epithermal beam, at Japan Research Reactor 4., Results: All patients achieved a complete response within 6 months of treatment. The median duration of the complete response was 24.0 months; the median overall survival time was 32.0 months. Three of the 5 patients are still alive; the other 2 died of distant metastatic disease. Open biopsy of the parotid gland after BNCT was performed in 1 patient and revealed no residual viable cancer cells and no serious damage to the normal glandular system. Although mild alopecia, xerostomia, and fatigue occurred in all patients, there were no severe adverse effects of grade 3 or greater., Conclusions: Our preliminary results demonstrate that BNCT is a potential curative therapy for patients with salivary gland carcinoma. The treatment does not cause any serious adverse effects, and may be used regardless of whether the primary tumor has been previously treated.

Background: Bevacizumab, an anti-vascular endothelial growth factor antibody, has been used for the treatment of radiation necrosis. Thus far, however, there has been no definitive report on its use for the treatment of symptomatic pseudoprogression. Here we report 2 cases of successful treatment with bevacizumab for symptomatic pseudoprogression after boron neutron capture therapy (BNCT) was applied for recurrent malignant gliomas., Methods: Two recurrent malignant gliomas received BNCT. Both cases were treated with intravenous administration of bevacizumab at the deterioration that seemed to be symptomatic pseudoprogression., Results: The first case was recurrent glioblastoma multiforme and the second was recurrent anaplastic oligoastrocytoma. Both cases recurred after standard chemoradiotherapy and were referred to our institute for BNCT, which is tumor-selective particle radiation. Just prior to neutron irradiation, PET with an amino acid tracer was applied in each case to confirm tumor recurrence. Both cases showed deterioration in symptoms, as well as on MRI, at intervals of 4 months and 2 months, respectively, after BNCT. For the first case, a second PET was applied in order to confirm no increase in tracer uptake. We diagnosed both cases as symptomatic pseudoprogression and started the intravenous administration of 5 mg/kg bevacizumab biweekly with 6 cycles. Both cases responded well to this, showing rapid and dramatic improvement in neuroimaging and clinical symptoms. No tumor progression was observed 8 months after BNCT., Conclusions: Bevacizumab showed marked effects on symptomatic pseudoprogression after BNCT. BNCT combined with bevacizumab may prolong the survival of patients with recurrent malignant gliomas.

Boron Neutron Capture Therapy (BNCT) involves the selective accumulation of boron carriers in tumor tissue followed by irradiation with a thermal or epithermal neutron beam. This therapy is therefore a cellular irradiation suited to treat tumors that have infiltrated into healthy tissues. BNCT has been used clinically to treat patients with cutaneous melanomas which have a high mortality. Human normal melanocytes and melanoma cells were treated with BNCT at different boronophenylalanine concentrations for signaling pathways analysis. BNCT induced few morphological alterations in normal melanocytes, with a negligible increase in free radical production. Melanoma cells treated with BNCT showed significant extracellular matrix (ECM) changes and a significant cyclin D1 decrease, suggesting cell death by necrosis and apoptosis and cell cycle arrest, respectively. BNCT also induced a significant increase in cleaved caspase-3 and a decrease in the mitochondrial electrical potential with selectivity for melanoma cells. Normal melanocytes had no significant differences due to BNCT treatment, confirming the data from the literature regarding the selectivity of BNCT. The results from this study suggest that some signaling pathways are involved in human melanoma treatment by BNCT, such as cell cycle arrest, ECM changes and intrinsic apoptosis., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Boron neutron capture therapy (BNCT) was proposed for untreatable colorectal liver metastases. The present study evaluates tumor control and potential radiotoxicity of BNCT in an experimental model of liver metastasis. BDIX rats were inoculated with syngeneic colon cancer cells DHD/K12/TRb. Tumor-bearing animals were divided into three groups: BPA-BNCT, boronophenylalanine (BPA) + neutron irradiation; Beam only, neutron irradiation; Sham, matched manipulation. The total absorbed dose administered with BPA-BNCT was 13 ± 3 Gy in tumor and 9 ± 2 Gy in healthy liver. Three weeks post-treatment, the tumor surface area post-treatment/pre-treatment ratio was 0.46 ± 0.20 for BPA-BNCT, 2.7 ± 1.8 for Beam only and 4.5 ± 3.1 for Sham. The pre-treatment tumor nodule mass of 48 ± 19 mg fell significantly to 19 ± 16 mg for BPA-BNCT, but rose significantly to 140 ± 106 mg for Beam only and to 346 ± 302 mg for Sham. For both end points, the differences between the BPA-BNCT group and each of the other groups were statistically significant (ANOVA). No clinical, macroscopic or histological normal liver radiotoxicity was observed. It is concluded that BPA-BNCT induced a significant remission of experimental colorectal tumor nodules in liver with no contributory liver toxicity.

The early promise of boron neutron capture therapy as a method for the treatment of cancer has been inhibited by the inherent toxicity associated with therapeutically useful doses of ¹⁰B-containing pharmacophores, the need for target-tissue specificity and the challenges imposed by biological barriers. Although developments in the synthetic chemistry of polyhedral boranes have addressed issues of toxicity to a considerable extent, the optimisation of the transport and the delivery of boronated agents to the site of action--the subject of this review--is a challenge that is addressed by the development of innovative formulation strategies., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Purpose: To investigate the efficacy and safety of boron neutron capture therapy (BNCT) in the treatment of inoperable head-and-neck cancers that recur locally after conventional photon radiation therapy., Methods and Materials: In this prospective, single-center Phase I/II study, 30 patients with inoperable, locally recurred head-and-neck cancer (29 carcinomas and 1 sarcoma) were treated with BNCT. Prior treatments consisted of surgery and conventionally fractionated photon irradiation to a cumulative dose of 50 to 98 Gy administered with or without concomitant chemotherapy. Tumor responses were assessed by use of the RECIST (Response Evaluation Criteria in Solid Tumors) and adverse effects by use of the National Cancer Institute common terminology criteria version 3.0. Intravenously administered L-boronophenylalanine-fructose (400 mg/kg) was administered as the boron carrier. Each patient was scheduled to be treated twice with BNCT., Results: Twenty-six patients received BNCT twice; four were treated once. Of the 29 evaluable patients, 22 (76%) responded to BNCT, 6 (21%) had tumor growth stabilization for 5.1 and 20.3 months, and 1 (3%) progressed. The median progression-free survival time was 7.5 months (95% confidence interval, 5.4-9.6 months). Two-year progression-free survival and overall survival were 20% and 30%, respectively, and 27% of the patients survived for 2 years without locoregional recurrence. The most common acute Grade 3 adverse effects were mucositis (54% of patients), oral pain (54%), and fatigue (32%). Three patients were diagnosed with osteoradionecrosis (each Grade 3) and one patient with soft-tissue necrosis (Grade 4). Late Grade 3 xerostomia was present in 3 of the 15 evaluable patients (20%)., Conclusions: Most patients who have inoperable, locally advanced head-and-neck carcinoma that has recurred at a previously irradiated site respond to boronophenylalanine-mediated BNCT, but cancer recurrence after BNCT remains frequent. Toxicity was acceptable. Further research on novel modifications of the method is warranted., (Copyright © 2012 Elsevier Inc. All rights reserved.)

To introduce our preliminary experience of treating locally and regionally recurrent Head and Neck cancer patients at Tsing Hua Open-Pool Reactor in Taiwan, four patients (M/F=3/1, median age 68 Y/O) were enrolled. BNCT with BPA (400 mg/kg) injected in 2 phases and prescription dose of 12-35 Gy (Eq.)/fraction for 2 fractions at 30 day interval can be given with sustained blood boron concentration and tolerable early toxicities for recurrent H & N cancer., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Given the clinical relevance of locoregional recurrences in head and neck cancer, we developed a novel experimental model of premalignant tissue in the hamster cheek pouch for long-term studies and demonstrated the partial inhibitory effect of a single application of Boron Neutron Capture Therapy (BNCT) on tumor development from premalignant tissue. The aim of the present study was to evaluate the effect of a double application of BNCT with a 6 week interval in terms of inhibitory effect on tumor development, toxicity and DNA synthesis. We performed a double application, 6 weeks apart, of (1) BNCT mediated by boronophenylalanine (BPA-BNCT); (2) BNCT mediated by the combined application of decahydrodecaborate (GB-10) and BPA [(GB-10+BPA)-BNCT] or (3) beam-only, at RA-3 nuclear reactor and followed the animals for 8 months. The control group was cancerized and sham-irradiated. BPA-BNCT, (GB-10+BPA)-BNCT and beam-only induced a reduction in tumor development from premalignant tissue that persisted until 8, 3, and 2 months respectively. An early maximum inhibition of 100% was observed for all 3 protocols. No normal tissue radiotoxicity was detected. Reversible mucositis was observed in premalignant tissue, peaking at 1 week and resolving by the third week after each irradiation. Mucositis after the second application was not exacerbated by the first application. DNA synthesis was significantly reduced in premalignant tissue 8 months post-BNCT. A double application of BPA-BNCT and (GB-10+BPA)-BNCT, 6 weeks apart, could be used therapeutically at no additional cost in terms of radiotoxicity in normal and dose-limiting tissues., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Purpose: To investigate the safety of boronophenylalanine-mediated boron neutron capture therapy (BNCT) in the treatment of malignant gliomas that progress after surgery and conventional external beam radiation therapy., Methods and Materials: Adult patients who had histologically confirmed malignant glioma that had progressed after surgery and external beam radiotherapy were eligible for this Phase I study, provided that >6 months had elapsed from the last date of radiation therapy. The first 10 patients received a fixed dose, 290 mg/kg, of L-boronophenylalanine-fructose (L-BPA-F) as a 2-hour infusion before neutron irradiation, and the remaining patients were treated with escalating doses of L-BPA-F, either 350 mg/kg, 400 mg/kg, or 450 mg/kg, using 3 patients on each dose level. Adverse effects were assessed using National Cancer Institute Common Toxicity Criteria version 2.0., Results: Twenty-two patients entered the study. Twenty subjects had glioblastoma, and 2 patients had anaplastic astrocytoma, and the median cumulative dose of prior external beam radiotherapy was 59.4 Gy. The maximally tolerated L-BPA-F dose was reached at the 450 mg/kg level, where 4 of 6 patients treated had a grade 3 adverse event. Patients who were given >290 mg/kg of L-BPA-F received a higher estimated average planning target volume dose than those who received 290 mg/kg (median, 36 vs. 31 Gy [W, i.e., a weighted dose]; p = 0.018). The median survival time following BNCT was 7 months., Conclusions: BNCT administered with an l-BPA-F dose of up to 400 mg/kg as a 2-hour infusion is feasible in the treatment of malignant gliomas that recur after conventional radiation therapy., (Copyright © 2011 Elsevier Inc. All rights reserved.)

In the present study the therapeutic effect and potential toxicity of the novel "Sequential" boron neutron capture therapy (Seq-BNCT) for the treatment of oral cancer was evaluated in the hamster cheek pouch model at the RA-3 Nuclear Reactor. Two groups of animals were treated with "Sequential" BNCT, i.e., BNCT mediated by boronophenylalanine (BPA) followed by BNCT mediated by sodium decahydrodecaborate (GB-10) either 24 h (Seq-24h-BNCT) or 48 h (Seq-48h-BNCT) later. In an additional group of animals, BPA and GB-10 were administered concomitantly [(BPA + GB-10)-BNCT]. The single-application BNCT was to the same total physical tumor dose as the "Sequential" BNCT treatments. At 28 days post-treatment, Seq-24h-BNCT and Seq-48h-BNCT induced, respectively, overall tumor responses of 95 ± 2% and 91 ± 3%, with no statistically significant differences between protocols. Overall response for the single treatment with (BPA + GB-10)-BNCT was 75 ± 5%, significantly lower than for Seq-BNCT. Both Seq-BNCT protocols and (BPA + GB-10)-BNCT induced reversible mucositis in the dose-limiting precancerous tissue around treated tumors, reaching Grade 3/4 mucositis in 47 ± 12% and 60 ± 22% of the animals, respectively. No normal tissue toxicity was associated with tumor response for any of the protocols. "Sequential" BNCT enhanced tumor response without an increase in mucositis in dose-limiting precancerous tissue., (© 2011 by Radiation Research Society)

Purpose: To clarify the role of p53 in boron neutron capture therapy (BNCT) for oral squamous cell carcinoma (SCC), the effect of BNCT on oral SCC xenografts with either wild-type or mutant-type p53 was examined., Materials and Methods: Oral SCC cells expressing either wild-type (SAS/neo) or mutant-type p53 (SAS/mp53) were used to produce nude mouse tumours. Tumour-bearing mice received boronophenylalanine (BPA) at a dose of 250 mg/kg and tumours were exposed to neutron irradiation., Results: After BNCT, the growth of SAS/neo and SAS/mp53 tumours was suppressed remarkably and all tumours became undetectable within two weeks. However, three of six SAS/mp53 tumours showed regrowth in two months. Histological examination of BNCT-treated tumours revealed chromosomal condensation, micronucleation, nuclear segmentation and intra- and intercelluar vacuolation. Notably, multinucleated giant cells appeared in SAS/mp53 tumours early after BNCT, suggesting mitotic catastrophe. In SAS/mp53 tumours treated with BNCT, a rapid decrease in phosphorylated cell division cycle 2 (cdc2) and a high level of cyclin B1, required for premature mitosis, were observed., Conclusion: These results indicate that BNCT suppressed oral SCC xenografts in nude mice efficiently, but cells survived in mutant-type p53 tumours. BNCT induces multinucleation which represents prestage of apoptosis or necrosis in oral SCC with mutant-type p53, but it may be also associated with the recurrence of BNCT-treated tumours.

A previous work concerning tumor control and skin damage in cutaneous melanoma treatments with BNCT has been extended to include doses, volumes and responses of 104 subcutaneous lesions from all patients treated in Argentina. Acute skin reactions were also scored for these patients, and cumulative dose-area histograms and dose-based figures of merit for skin were calculated. Broadening the tumor response analysis with the latest data showed that the (minimum or mean) tumor dose is not a good predictor of the observed clinical outcome by itself. However, when the tumor volume was included in the model as second explicative variable, the dose increases its significance and becomes a critical variable jointly with the volume (p-values<0.05). A preliminary analysis to estimate control doses for two groups of tumor sizes revealed that for small tumor volumes (< 0.1cm(3)) doses greater than 20 Gy-Eq produce a high tumor control (> 80%). However, when tumor volumes are larger than 0.1cm(3), control is moderate (< 40%) even for minimum doses up to 40 Gy-Eq. Some quantities based on skin doses, areas and complication probabilities were proposed as candidates for predicting the severity of the early skin reactions. With the current data, all the evaluated figures of merit derived similar results: ulceration is present among the cases for which these quantities take the highest values.

It is necessary to explore new treatments for recurrent head and neck malignancies (HNM) to avoid severe impairment of oro-facial structures and functions. Boron neutron capture therapy (BNCT) is tumor-cell targeted radiotherapy that has significant superiority over conventional radiotherapies in principle. We have treated with BNCT 42 times for 26 patients (19 squamous cell carcinomas (SCC), 4 salivary gland carcinomas and 3 sarcomas) with a recurrent and far advanced HNM since 2001. Results of (1) (10)B concentration of tumor/normal tissue ratios (T/N ratio) of FBPA-PET studies were SCC: 1.8-5.7, sarcoma: 2.5-4.0, parotid tumor: 2.5-3.7. (2) Therapeutic effects were CR: 12 cases, PR: 10 cases, PD: 3 cases NE (not evaluated): 1 case. Response rate was 85%. (3) Improvement of QOL such as a relief of severe pain, bleeding, and exudates at the local lesion, improvement of PS, disappearance of ulceration, covered with normal skin and preserved oral and maxillofacial functions and tissues. (4) Survival periods after BNCT were 1-72 months (mean: 13.6 months). Six-year survival rate was 24% by Kaplan-Meier analysis. (5) Adverse-events were transient mucositis and alopecia in most of the cases; three osteomyelitis and one brain necrosis were recognized. These results indicate that BNCT represents a new and promising treatment approach for advanced HNM.

Neutron capture therapy (NCT) theoretically allows an unique tumor-cell-selective high-LET particle radiotherapy. The survival benefits and safety of NCT were evaluated in 15 patients with newly diagnosed glioblastoma multiforme (GBM). Seven patients received intra-operative (IO-) NCT and eight patients received external beam (EB-) NCT. Sulfhydryl borane (BSH, 5 g/body) was administered intravenously 12 h before neutron irradiation. Additionally, p-dihydroxyboryl-phenylalanine (BPA, 250 mg/kg) was given 1 h before irradiation to the eight patients who underwent EB-NCT. EB-NCT was combined with fractionated photon irradiation. Five of 15 patients were alive at analysis for a mean follow-up time of 20.3 M. In 11 of 15 patients followed up for more than 1-year, eight (72.7%) maintained their Karnofsky performance status (KPS; 90 in 6 and 100 in 2). The median overall survival (OS) and time to magnetic resonance (MR) change (TTM) for all patients were 25.7 and 11.9 M, respectively. There was no difference in TTM between the IO-NCT (12.0 M) and EB-NCT (11.9 M) groups. The 1- and 2-year survival rates were 85.7% and 45.5%, respectively. This NCT pilot study in 15 patients with newly diagnosed GBM showed survival benefits, suggesting that the neutron capture reaction may function sufficiently to control tumors locally, and that further optimized studies in large series of patients are warranted.

The National Atomic Energy Commission of Argentina (CNEA) constructed a novel thermal neutron source for use in boron neutron capture therapy (BNCT) applications at the RA-3 research reactor facility located in Buenos Aires. The aim of the present study was to perform a dosimetric characterization of the facility and undertake radiobiological studies of BNCT in an experimental model of oral cancer in the hamster cheek pouch. The free-field thermal flux was 7.1 x 10(9) n cm(-2)s(-1) and the fast neutron flux was 2.5 x 10(6) n cm(-2)s(-1), indicating a very well-thermalized neutron field with negligible fast neutron dose. For radiobiological studies it was necessary to shield the body of the hamster from the neutron flux while exposing the everted cheek pouch bearing the tumors. To that end we developed a lithium (enriched to 95% in (6)Li) carbonate enclosure. Groups of tumor-bearing hamsters were submitted to BPA-BNCT, GB-10-BNCT, (GB-10+BPA)-BNCT or beam only treatments. Normal (non-cancerized) hamsters were treated similarly to evaluate normal tissue radiotoxicity. The total physical dose delivered to tumor with the BNCT treatments ranged from 6 to 8.5 Gy. Tumor control at 30 days ranged from 73% to 85%, with no normal tissue radiotoxicity. Significant but reversible mucositis in precancerous tissue surrounding tumors was associated to BPA-BNCT. The therapeutic success of different BNCT protocols in treating experimental oral cancer at this novel facility was unequivocally demonstrated.

A Matlab-based computational tool, named SPHERE, was developed that helps determining tumor and skin doses in BNCT treatments. It was especially designed for cutaneous melanoma treatments and, among its features, it provides a guide for the location and delineation of tumors and a visual representation of superficial dose distributions (for both tumor and normal tissues). It also generates cumulative dose-volume histograms for different volumes of interest and dose-area histograms for skin. A description of the tool is presented, as well as examples of its application.

To investigate bystander mutagenic effects induced by alpha particles during boron neutron capture therapy (BNCT), we mixed cells that were electroporated with borocaptate sodium (BSH), which led to the accumulation of (10)B inside the cells, with cells that did not contain the boron compound. BSH-containing cells were irradiated with alpha particles produced by the (10)B(n,alpha)(7)Li reaction, whereas cells without boron were only affected by the (1)H(n,gamma)(2)H and (14)N(n,rho)(14)C reactions. The frequency of mutations induced in the hypoxanthine-guanine phosphoribosyltransferase (HPRT) locus was examined in Chinese hamster ovary (CHO) cells irradiated with neutrons (Kyoto University Research Reactor: 5 MW). Neutron irradiation of 1:1 mixtures of cells with and without BSH resulted in a survival fraction of 0.1, and the cells that did not contain BSH made up 99.4% of the surviving cell population. Using multiplex polymerase chain reactions (PCRs), molecular structural analysis indicated that most of the mutations induced by the bystander effect were point mutations and that the frequencies of total and partial deletions induced by the bystander effect were lower than those resulting from the alpha particles produced by the (10)B(n,alpha)(7)Li reaction or the neutron beam from the (1)H(n,gamma)(2)H and (14)N(n,rho)(14)C reactions. The types of point mutations induced by the BNCT bystander effect were analyzed by cloning and sequencing methods. These mutations were comprised of 65.5% base substitutions, 27.5% deletions, and 7.0% insertions. Sequence analysis of base substitutions showed that transversions and transitions occurred in 64.7% and 35.3% of cases, respectively. G:C-->T:A transversion induced by 8-oxo-guanine in DNA occurred in 5.9% of base substitution mutants in the BNCT bystander group. The characteristic mutations seen in this group, induced by BNCT alpha particles, differed from those typical of gamma ray radiation.

Almost eight years ago, in December 2001, we performed for the first time in the world thermal neutron irradiation on an isolated liver of a patient. The organ was affected by diffuse metastases of a colon carcinoma and had been previously loaded with a (10)B compound. In July 2003, the same procedure was applied again on a patient for the treatment of unresectable and incurable hepatic metastases of a carcinoma of the rectum. Both patients are dead at present. Now we can analyze in depth the clinical history of these patients and evaluate the effectiveness of this therapy. From this exciting experience we learned much, and we also found out about complications till then unknown, which need to be studied and addressed experimentally. Unfortunately we can base our conclusions just on the experience we had with these two patients. We could have been much more detailed and firm in our statements if the number of clinical cases was larger. The BNCT Pavia project has been suspended, but it is more than likely to resume in a short time. Good findings were many. The procedure is feasible; the original concept of complete immersion of the diseased liver in a homogeneous neutron field proved effective and winning. The tumor masses resulted completely necrotic and unknown metastases too appeared radically treated; healthy hepatic tissue was preserved from both morphological and functional points of view; no symptoms of cirrhosis appeared even four years after treatment. For the long term surviving patient, quality of life was excellent. Other findings require to be tackled in depth. The "post-irradiation syndrome" we observed in both patients, with identical symptoms and biochemical derangements, creates a dramatic--even though totally reversible--clinical condition, that is the probable cause of death for our second patient, suffering from cardiomyopathy, 33 days after treatment. For the first patient, recurrences were a late yet fatal complication, for which even a further surgical revision was ineffective. We offer some hypotheses about their origin and possible prevention.

We recently initiated a program aimed to investigate the suitability of dynamic infrared imaging for following-up nodular melanoma patients treated with BNCT. The reason that makes infrared imaging attractive is the fact that it constitutes a functional and non-invasive imaging method, providing information on the normal and abnormal physiologic response of the nervous and vascular systems, as well as the local metabolic rate and inflammatory processes that ultimately appear as differences in the skin temperature. An infrared camera, with a focal plane array of 320 x 240 uncooled ferroelectric detectors is employed, which provides a video stream of the infrared emission in the 7-14 microm wavelength band. A double blackbody is used as reference for absolute temperature calibration. After following a protocol for patient preparation and acclimatization, a basal study is performed. Subsequently, the anatomic region of interest is subjected to a provocation test (a cold stimulus), which induces an autonomic vasoconstriction reflex in normal structures, thus enhancing the thermal contrast due to the differences in the vasculature of the different skin regions. Radiation erythema reactions and melanoma nodules possess typically a faster temperature recovery than healthy, non-irradiated skin. However, some other non-pathological structures are also detectable by infrared imaging, (e.g. scars, vessels, arteriovenous anastomoses and injuries), thus requiring a multi-study comparison in order to discriminate the tumor signal. Besides the superficial nodules, which are readily noticeable by infrared imaging, we have detected thermal signals that are coincident with the location of non-palpable nodules, which are observable by CT and ultrasound. Diffuse regions of fast temperature recovery after a cold stimulus were observed between the third and sixth weeks post-BNCT, concurrent with the clinical manifestation of radiation erythema. The location of the erythematous visible and infrared regions is consistent with the 3D dosimetry calculations.