Clinical outcomes and factors involved in the local control of proton beam therapy for oligometastatic liver tumors in patients with colorectal cancer

The Japanese nationwide cohort data of proton beam therapy for liver oligometastasis in breast cancer patients

A nationwide multicenter cohort study on particle therapy was launched by the Japanese Society for Radiation Oncology in Japan in May 2016. We analyzed the outcome of proton beam therapy (PBT) for liver oligometastasis in breast cancers. Cases in which PBT was performed at all Japanese proton therapy facilities between May 2016 and February 2019 were enrolled. The patients were selected based on the following criteria: the primary cancer was controlled, liver recurrence without extrahepatic tumors and no more than three liver lesions. Fourteen females, with a median age of 57 years (range, 44-73) and 22 lesions, were included. The median lesion size, fraction (fr) size and biological effective dose were 44 (20-130) mm, 6.6 (2-8) gray (Gy) (relative biological effectiveness)/fr and 109.6 (52.7-115.2) Gy, respectively. The median follow-up period was 22.8 (4-54) months. The 1-, 2- and 3-year local control (LC) rates of liver metastasis from breast cancer were 100% for all. The 1-, 2- and 3-year overall survival rates were 85.7, 62.5 and 62.5%, respectively. The 1-, 2- and 3-year progression-free survival (PFS) rates were 50.0%, 33.3%, and 16.7%, respectively. The median PFS time was 16 months. Only one patient did not complete PBT due to current disease progression. One patient had Grade 3 radiation-induced dermatitis. None of the patients experienced radiation-induced liver failure during the acute or late phase. Owing to the low incidence of adverse events and the high LC rate, PBT appears to be a feasible option for liver oligometastasis in breast cancers.

Proton Beam Therapy for Lung Oligometastatic Recurrence in Patients With Esophageal Cancer

Local treatment of oligometastatic esophagogastric cancer has been reported to improve overall survival (OS) compared to systemic therapy alone. This study evaluated the feasibility and safety of proton beam therapy (PBT) for the treatment of lung oligometastatic recurrence in esophageal cancer patients. This single-center historical cohort study enrolled 11 patients who underwent PBT for lung oligometastasis from esophageal cancer between 2010 and 2019. The selection criteria were that the primary esophageal cancer was controlled and no more than three lung metastases without outside lung tumors were present. OS, progression-free survival (PFS), and local control (LC) rates and adverse events (AEs) were assessed. Factors that may be related to OS were also investigated. The median follow-up period was 27.8 months (8.8-141.3 months). The one-, two-, and three-year OS rates were 81.8%, 72.7%, and 51.9%, respectively (median OS time: 43.7 months); PFS rates were 45.5%, 27.3%, and 27.3%, respectively (median PFS time: 8.8 months); and LC rates were 92.3%, 72.7%, and 72.7%, respectively. The eighth edition of tumor-node-metastasis (TNM) classification for esophageal cancer was the only significant OS-related factor (p = 0.0309). No grade ≥ 3 AEs were observed. Based on the low incidence of AEs and acceptable LC rate, PBT is a feasible option for the treatment of lung oligometastasis in esophageal cancer patients.

The Japanese nationwide cohort data of proton beam therapy for liver oligometastasis in esophagogastric cancer patients

A nationwide multicenter cohort study on particle therapy was launched by the Japanese Society for Radiation Oncology in Japan in May 2016. We analyzed the outcome of proton beam therapy (PBT) for liver oligometastasis of esophagogastric cancers. Cases in which PBT was performed at all PBT facilities in Japan between May 2016 and February 2019 were enrolled. The patients were selected based on the following criteria: controlled primary cancer, liver recurrence without extrahepatic tumors and no more than three liver lesions. Twenty-two males and two females with a median age of 69 (range, 52-80) years and 35 lesions were included. This study included 6 patients with esophageal and 18 patients with gastric cancer. The median lesion size, fraction size and biological effective dose (BED)10 were 32 (7-104) mm, 3.8 gray (relative biological effect)/fractions (Gy (RBE)/fr) (2-8 Gy (RBE)/fr) and 96.9 (88.8-115.2) Gy, respectively. The median follow-up period was 18 (4-47) months. The 1-, 2- and 3-year overall survival (OS) rates were 75, 51.8 and 45.3%, respectively, and the median OS was 25.3 months. The 1-, 2- and 3-year cumulative local recurrence (LR) rates were 3, 6 and 6%, respectively. Patients' age (P < 0.01), performance status (P = 0.017) and tumor size (P = 0.024) were significant OS-related factors. No Grade 3 or higher adverse events (AEs) were observed. Owing to the low incidence of AEs and the low LR cumulative incidence, PBT is a feasible option for liver oligometastasis of esophagogastric cancers.