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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]

The feasibility and efficacy of particle beam therapy (PBT) using protons or carbon ions were compared with those of photon-based stereotactic body radiotherapy (SBRT) for primary renal cell carcinoma (RCC) via a systematic review and nationwide registry for PBT (Japanese Society for Radiation Oncology [JASTRO] particle therapy committee). Between July 2016 and May 2019, 20 patients with non-metastatic RCC who were treated at six Japanese institutes (using protons at three, using carbon ions at the other three) were registered in the nationwide database and followed up prospectively. The 20 patients comprised 15 men and had a median age of 67 (range: 57–88) years. The total radiation dose was 66–79.6 Gy (relative biological effectiveness [RBE]). Over a median follow up of 31 months, the 3-year rates of overall survival (OS) and local control (LC) were 100% and 94.4%, respectively. No grade ≥ 3 toxicities were observed. Based on a random effects model, a meta-analysis including the present results revealed 3-year OS rates after SBRT and PBT of 75.3% (95% CI: 57.3–86.6) and 94.3% (95% CI: 86.8–97.6), respectively (P  = 0.005), but the difference in LC rates between the two methods was not observed (P  = 0.63). PBT is expected to have similar if not better treatment results compared with SBRT for primary renal cancer. In particular, PBT was shown to be effective even for large RCC and could provide a therapeutic option when SBRT is not indicated. [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]