婦人科がんのリンパ節転移に対する陽子線再照射の現状と可能性

Proton beam re-irradiation for lymph node metastases in gynecologic cancers：current status and future perspectives

近年，我が国の陽子線治療体制は着実に拡充しており，2026年4月時点で陽子線単独施設18施設に加え，陽子線・重粒子線併設施設が1施設稼働している^1）。この施設整備は，頭頸部腫瘍，小児腫瘍，前立腺癌，骨軟部腫瘍など，線量集中性の利点が大きい領域における臨床応用を後押ししてきた。他方で，婦人科がんに対する陽子線治療の位置づけは限定的で，日本放射線腫瘍学会（JASTRO）の保険適用一覧に含まれておらず^2），先進医療Aとして実施する疾患別統一治療方針でも婦人科がんの記載は乏しい^3）。

Proton beam re-irradiation for lymph node recurrence in gynecologic cancers is emerging as a promising option for patients previously treated with radiotherapy. In such cases, re-treatment is often limited by the tolerance of nearby organs, including the bowel, bladder, rectum, ureters, and kidneys. Owing to its physical advantage of the Bragg peak, proton therapy may improve local control while reducing severe toxicity. Recent reports have shown encouraging outcomes in selected patients with limited recurrent disease. Further advances in spacer placement and precise techniques such as IMPT may expand its applicability. Future progress will depend on better patient selection and prospective multi-institutional data.