We investigated clinical outcomes of proton beam concurrent chemoradiotherapy (CCRT) for unresectable, locally advanced pancreatic cancer (LAPC) patients. Records from 42 unresectable LAPC patients (21 male and 21 female, 39-83 years old) with IIB/III clinical staging of 1/41 treated by proton beam CCRT were retrospectively reviewed. Twelve patients received a conventional 50 Gray equivalents (GyE) in 25 fractions protocol and 30 others received a higher dose protocol of 54.0-67.5 GyE in 25-33 fractions. Gemcitabine or S-1 (Tegafur, Gimeracil and Oteracil) was used concurrently. Toxicity, overall survival (OS) and local control (LC) were examined. Acute adverse events of grades 1, 2, 3 and 4 were found in 4, 15, 17 and 2 patients, respectively. All grade 3 and 4 events were hematologic. Late adverse events of grades 1 and 2 were found in 3 and 2 patients, respectively. No late adverse effects of grade 3 or higher were observed. The 1-year/2-year OS rates from the start of CCRT were 77.8/50.8% with median survival time (MST) of 25.6 months. The 1-year/2-year LC rate from CCRT start was 83.3/78.9% with a median time to local recurrence of more than 36 months. Total irradiation dose was the only significant factor in univariate analyses of OS and LC (p = 0.015 and 0.023, respectively). Proton beam CCRT lengthened survival periods compared to previous photon CCRT data and higher dose irradiation prolonged LC and OS for unresectable LAPC patients. Proton beam therapy is therefore safe and effective in these cases.

Background/Aim: Curing local recurrence of rectal cancer (LRRC) is difficult with conventional photon radiotherapy. Proton beam therapy (PBT) on the other hand, has unique physical characteristics that permit higher doses to LRRC while minimizing side effects on surrounding organs. However, the efficacy of PBT on controlling rectal cancer recurrence has not yet been reported. This study aimed to evaluate clinical outcomes and toxicities of PBT for LRRC. Patients and Methods: Clinical outcomes were retrospectively evaluated for 12 patients with 13 total lesions that had received PBT for LRRC at our institute. Results: The median follow-up period from the initiation of PBT was 35.6 months. The 3-year local control, progression-free survival and overall survival rates were 80.2%, 10.4% and 73.8%, respectively. Median survival time was 67.1 months. There were no severe acute or late adverse events. Conclusion: PBT could be a safe and effective treatment method for LRRC.

Carbon‐ions are charged particles with a high linear energy transfer, and therefore, they make a better dose distribution with greater biological effects on the tumors compared with photons and protons. Since prostate cancer, renal cell carcinoma, and retroperitoneal sarcomas such as liposarcoma and leiomyosarcoma are known to be radioresistant tumors, carbon‐ion radiotherapy, which provides the advantageous radiobiological properties such as an increasing relative biological effectiveness toward the Bragg peak, a reduced oxygen enhancement ratio, and a reduced dependence on fractionation and cell‐cycle stage, has been tested for these urological tumors at the National Institute for Radiological Sciences since 1994. To promote carbon‐ion radiotherapy as a standard cancer therapy, the Japan Carbon‐ion Radiation Oncology Study Group was established in 2015 to create a registry of all treated patients and conduct multi‐institutional prospective studies in cooperation with all the Japanese institutes. Based on accumulating evidence of the efficacy and feasibility of carbon‐ion therapy for prostate cancer and retroperitoneal sarcoma, it is now covered by the Japanese health insurance system. On the other hand, carbon‐ion radiotherapy for renal cell cancer is not still covered by the insurance system, although the two previous studies showed the efficacy. In this review, we introduce the characteristics, clinical outcomes, and perspectives of carbon‐ion radiotherapy and our efforts to disseminate the use of this new technology worldwide.

Impairment of bone growth after radiotherapy for pediatric bone cancer is a well-known adverse event. However, there is limited understanding of the relationship between bone growth and irradiation dose. In this study, we retrospectively analyzed bone growth impairment after proton beam therapy for pediatric cancer. A total of 353 vertebral bodies in 23 patients under 12 years old who received proton beam therapy were evaluated. Compared to the non-irradiated vertebral body growth rate, the irradiated vertebral body rate (%/year) was significantly lower: 77.2%, 57.6%, 40.8%, 26.4%, and 14.1% at 10, 20, 30, 40, and 50 Gy (RBE) irradiation, respectively. In multivariate analysis, radiation dose was the only factor correlated with vertebral body growth. Age, gender, and vertebral body site were not significant factors. These results suggest that the growth rate of the vertebral body is dose-dependent and decreases even at a low irradiated dose. This is the first report to show that proton beam therapy has the same growth inhibitory effect as photon radiotherapy within the irradiated field.

We assessed the development of lymphopenia during concurrent chemoradiotherapy (CRT) using X-ray versus proton beams and the impact on survival in patients with esophageal cancer. Among patients with esophageal cancer who were administered concurrent CRT with a curative intent at our institute from 2014 to 2018, 69 (15 receiving X-ray radiotherapy (XRT) and 54 receiving proton beam therapy [PBT]) who underwent weekly blood testing during treatment were enrolled. The absolute lymphocyte counts (ALC) at 1, 5 and 6 weeks were significantly higher in the patients who received PBT than in those who received XRT (p = 0.002, p = 0.006 and p = 0.009, respectively), and a similar trend in the neutrophil-to-lymphocyte ratio (NLR) was observed (p = 0.003 at 5 weeks). The 2-year overall survival (OS) and progression-free survival (PFS) rates tended to be higher in the patients who maintained an ALC ≥200 compared with those who did not (p = 0.083 and p = 0.053, respectively), and similar trends were observed in the NLR (p = 0.061 and p = 0.038, respectively). Dose–volume analysis revealed significant correlations between volumes of the thoracic bones irradiated by 5–50 Gy and minimum ALCs and maximum NLR. These findings suggested that PBT prevented the development of lymphopenia during CRT by reducing the irradiated volume of the thoracic bone, and the maintained lymphocyte count is possibly one of the early predictors for survival in patients with esophageal cancer.

Background and Aims: Hepatocellular carcinoma (HCC) patients with Child‐Pugh (CP)‐B not eligible for surgery nor other focal therapy options due to impaired liver function, have very limited treatment options. This study aims to retrospectively investigate the toxicity and efficacy of Carbon‐ion radiotherapy (C‐ion RT) on HCC with CP‐B patients.Materials and Methods: Patients with CP‐B, no extrahepatic metastasis, and treated with C‐ion RT between May 2000 and March 2020 were retrospectively extracted and included in this study.Results: Sixty‐nine lesions of 58 patients were included. The median follow‐up duration was 20.5 (2.7–108) months. During follow‐up, recurrence was observed in 43 patients, including 2 local recurrences and 39 intrahepatic recurrences beyond the irradiation field. A grade 3 acute hepatotoxicity was observed in one patient during the observation period. No acute or late adverse event of grade ≥4 was observed. Overall survival was 80.4% and 46.0% at 1 and 2 years, respectively, and the median survival time was 22.6 months. Local control rate was 96.4% at both 1 and 2 years, and progression‐free survival was 38.6% and 6.9% at 1 and 2 years, respectively, with a median of 9.7 months.Conclusion: The C‐ion RT showed low toxicity and good local effect in patients with HCC and CP‐B. Therefore, C‐ion RT could be an appropriate treatment for patients with HCC with poor liver function.