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Reports on the therapeutic efficacy and safety of carbon‐ion radiotherapy (C‐ion RT) for oligometastatic liver disease are limited, with insufficient evidence. This study aimed to evaluate the clinical outcomes of C‐ion RT for oligometastatic liver disease at all Japanese facilities using the nationwide cohort data. We reviewed the medical records to obtain the nationwide cohort registry data on C‐ion RT between May 2016 and June 2020. Patients (1) with oligometastatic liver disease as confirmed by histological or diagnostic imaging, (2) with ≤3 synchronous liver metastases at the time of treatment, (3) without active extrahepatic disease, and (4) who received C‐ion RT for all metastatic regions with curative intent were included in this study. C‐ion RT was performed with 58.0–76.0 Gy (relative biological effectiveness [RBE]) in 1–20 fractions. In total, 102 patients (121 tumors) were enrolled in this study. The median follow‐up duration for all patients was 19.0 months. The median tumor size was 27 mm. The 1‐year/2‐year overall survival, local control, and progression‐free survival rates were 85.1%/72.8%, 90.5%/78.0%, and 48.3%/27.1%, respectively. No patient developed grade 3 or higher acute or late toxicity. C‐ion RT is a safe and effective treatment for oligometastatic liver disease and may be beneficial as a local treatment option in multidisciplinary treatment. [ABSTRACT FROM AUTHOR]

Background & Aims: Carbon‐ion radiation therapy has shown encouraging results in hepatocellular carcinoma patients in single‐centre studies. We evaluated the effectiveness and safety of short‐course carbon‐ion radiation therapy for hepatocellular carcinoma in a multicentre study conducted by the Japan Carbon Ion Radiation Oncology Study Group. Methods: Consecutive hepatocellular carcinoma patients who were treated with carbon‐ion radiation therapy in four or fewer fractions at four Japanese institutions between April 2005 and November 2014 were analysed retrospectively. The primary outcome was overall survival; secondary outcomes were local control rate, treatment‐related toxicity and radiation‐induced liver disease. Results: A total of 174 patients were included in this study. Prescribed carbon‐ion radiation therapy doses were (relative biological effectiveness): 48.0 Gy in two fractions (n = 46), and 52.8 Gy (n = 108) and 60.0 Gy (n = 20) in four fractions. The median follow‐up period was 20.3 (range, 2.9‐103.5) months. The overall survival and local control rates at 1, 2 and 3 years were 95.4%, 82.5% and 73.3%; and 94.6%, 87.7% and 81.0% respectively. Multivariate analysis revealed that Eastern Cooperative Oncology Group performance status 1‐2, Child‐Pugh class B, maximum tumour diameter ≥3 cm, multiple tumours and serum alpha foetoprotein level >50 ng/mL were significant prognostic factors of overall survival. No treatment‐related death occurred during the follow‐up period. Grades 3 or 4 treatment‐related toxicities were observed in 10 patients (5.7%); radiation‐induced liver disease was observed in three patients (1.7%). Conclusions: Short‐course carbon‐ion radiation therapy is a safe, effective and potentially curative therapy for hepatocellular carcinoma. See Editorial on Page 2132 [ABSTRACT FROM AUTHOR]

Recent advances in external beam radiotherapy have allowed us to deliver higher doses to the tumors while decreasing doses to the surrounding tissues. Dose escalation using high-precision radiotherapy has improved the treatment outcomes of prostate cancer. Intensity-modulated radiation therapy has been widely used throughout the world as the most advanced form of photon radiotherapy. In contrast, particle radiotherapy has also been under development, and has been used as an effective and non-invasive radiation modality for prostate and other cancers. Among the particles used in such treatments, protons and carbon ions have the physical advantage that the dose can be focused on the tumor with only minimal exposure of the surrounding normal tissues. Furthermore, carbon ions also have radiobiological advantages that include higher killing effects on intrinsic radio-resistant tumors, hypoxic tumor cells and tumor cells in the G0 or S phase. However, the degree of clinical benefit derived from these theoretical advantages in the treatment of prostate cancer has not been adequately determined. The present article reviews the available literature on the use of particle radiotherapy for prostate cancer as well as the literature on the physical and radiobiological properties of this treatment, and discusses the role and the relative merits of particle radiotherapy compared with current photon-based radiotherapy, with a focus on proton beam therapy and carbon ion radiotherapy. [ABSTRACT FROM AUTHOR]