ESTRO 2025 - Abstract Book

S1462

Clinical – Mixed sites & palliation

ESTRO 2025

385

Digital Poster The Japanese nationwide registry data analysis of particle beam therapy for metastatic liver cancers Nobuyoshi Fukumitsu 1 , Shintaro Shiba 2 , Kei Shibuya 3 , Daijiro Kobayashi 3 , Yuhei Miyasaka 3 , Hisashi Yamaguchi 4 , Haruko Numajiri 5 , Masaru Wakatsuki 1 , Hiroyuki Ogino 6 , Norio Katoh 7 1 Radiation Oncology, Kobe Proton Center, Kobe, Japan. 2 Radiation Oncology, Shonan Kamakura General Hospital, Kamakura, Japan. 3 Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Japan. 4 Radiation Oncology, The Ohio State University, Ohio, USA. 5 Radiation Oncology, Tsukuba University School of Medicine, Tsukuba, Japan. 6 Radiation Oncology, Kobe ProtoNagoya Proton Therapy Centern Center, Nagoya, Japan. 7 Radiation Oncology, Hokkaido University Faculty of Medicine, Sapporo, Japan Purpose/Objective: The Japanese Society for Radiation Oncology has been providing particle beam therapy for the indications defined in the unified treatment policy since May 2016. All cases have been prospectively registered and working groups have been formed for each disease to analyze the prospective registration data. Metastatic liver cancer is regarded more as an optional treatment when no alternative therapy is available. Results: As of December 2019, there were 323 cases registered for particle beam therapy. Of these, the largest number of cases were classified by primary disease, with 167 cases in the colon, followed by 36 cases in the biliary tract, 29 cases in the pancreas, 27 cases in the stomach, 17 cases in the breast, and 11 cases in the esophagus. The above six major disease groups were divided into two groups according to tumor size (>5 cm or ≤5 cm), number (single or multiple), and concurrent treatment (with or without). Overall survival was 68% at 2 years and 36% at 5 years. Median survival time (MST) was 37.2 months. Grade 3 and 4 adverse events were observed in 10 patients (dermatitis: 6, hepatobiliary system disorder: 3, anemia: 1). Long-term MST was 65.7 months or longer for breast cancer (no combination therapy) and breast cancer (single lesion). Next, long-term MST of more than 3 years was 55.5 months for colorectal cancer (with concurrent therapy), 42.5 months for gastric cancer (≤5 cm in diameter), 39.8 months for colorectal cancer (single lesion), 39.8 months for colorectal cancer (≤5 cm in diameter), and 36 months for colorectal cancer (without concurrent therapy). Conclusion: It is clear that, under appropriate conditions, particle beam therapy can provide long-term survival in many cases, especially in breast and colorectal cancers. Material/Methods: This study examines the results of particle beam therapy for oligometastatic liver cancer.

Keywords: particle beam radiotherapy, liver metastasis

504

Digital Poster Spine SBRT for Metastatic Breast Cancer: Analysis by Biologic Subtype Boris A Mueller, Christopher Jackson, Diana Roth O'Brien, Yoshiya Yamada, Higginson Daniel, Lior Z Braunstein Radiation Oncology, MSKCC, NEW YORK, USA Purpose/Objective: Stereotactic body radiotherapy (SBRT) enables superior local control of breast cancer spinal metastases compared to conventional radiotherapy. However, limited data exist to optimize SBRT dosing schemes in this setting, and little