放射線治療後に再発した脊椎転移に対する術中照射療法の成績

Results of Intraoperative Radiotherapy for Recurrence of Spinal Metastasis Previously Treated by External Radiotherapy

　放射線根治線量治療後の転移性脊椎腫瘍再発に対して，後方手術（除圧と脊椎内固定）に加えて，開創したまま転移巣に放射線照射を行う方法（術中照射療法，以下IORT）を行ってきた．IORTは開創して脊髄を遮蔽して行うことにより皮膚障害や脊髄障害を防ぐことができる．今回66例76手術の成績と同時期に行われた放射線照射の既往のない転移性脊椎腫瘍94例96手術の成績とを比較検討したところ，麻痺の改善，局所制御とも後者には劣るものの，従来報告されている通常の後方手術の成績に比べて良好であった．

　Because of the high risk of radiation myelopathy and skin disorders external radiotherapy (ERT) cannot be used to treat recurrent spinal metastasis after previous treatment with the maximum dose of ERT. We have used a combination of conventional posterior surgery and intraoperative radiotherapy (IORT) to manage such lesions, because it allows the radiation dose to the spinal cord and the skin to be minimized. Sixty-six patients were treated by IORT a total of 76 times. At least one level improvement according to Frankel's classification was achieved in 36 (61％) of the 59 cases with motor weakness. Nine (18％) of the 50 patients followed up for more than 6 months developed a re-recurrence, the tumors at the primary cancer sites in the re-recurrence cases were radioresistant. Although these results were poorer than the results of de novo IORT for spinal metastasis without a history of ERT (94 patients, IORT 96 times), they were more favorable than the results of conventional posterior surgery alone.