(P 354) PROTON BEAM THERAPY FOR PEDIATRIC AND ADOLESCENT SARCOMA FROM OVERSEAS

Objective: Proton beam therapy (PBT) is currently an important therapeutic option in the multidisciplinary treatment of pediatric and adolescent sarcoma because of its potential to reduce late complications. Precise tailoring of proton beams reduces radiation-related long-term side effects and induction of secondary malignancies, which is of particular importance in terms of quality of life. However, there are not many institutions where pediatric proton therapy is available in Japan and China. Because our hospital, National Cancer Center Hospital East (NCCHE), is one of a few facilities where PBT is available, we have been treating pediatric and adolescent patients from inside and outside Japan. In this report we evaluated patients with pediatric and adolescent sarcoma who received PBT at our institute from overseas, mainly focusing on the safety and feasibility.

Methods: We retrospectively investigated 76 pediatric and adolescent sarcoma patients from China, who received PBT in NCCHE between 2018 and 2023. Data on patient characteristics, multimodality therapy, adverse events, and oncologic endpoints were evaluated. Adverse events were assessed during, and after PBT according to common terminology criteria for adverse events (CTCAE) V4.0.

Results: Seventy-six patients were evaluated. Diseases included 51(67%) rhabdomyosarcoma, 10(13%) Ewing sarcoma, 6 (11%) chordoma, 7 (9%) other soft tissue sarcomas (STSs). There were 64 first-onset cases and 12 recurrent cases. All patients came to our hospital with the help from Japanese or Chinese agents. The agents arranged hospital appointments, medical interpreters and accommodations. A medical interpreter was always accompanied by the patient during medical treatment, which facilitated the explanation of treatment and understanding of side effects. All patients received continuous care by local medical facilities during and after PBT in NCCHE. No Grade 4 or higher adverse events were observed, but mucositis and dermatitis were more severe in patients receiving concomitant chemotherapy than in those with PBT alone. Except for two patients, the treatment was safely completed and the patients were able to return home. The completion rate was 97%. Two patients with rhabdomyosarcoma returned China before PBT was started due to findings of meningeal dissemination on pre-treatment imaging scans. No significantly delays in the intervals of chemotherapy caused by international travels were observed.

Conclusion: PBT for pediatric and adolescent sarcoma patients from another country could be safely administered in combination with chemotherapy. It appears feasible to treat pediatric and adolescent patients from overseas by establishing a medical treatment system, including before, during, and after their trip.