α線放出核種による癌治療の進歩と放射線治療の中の位置づけ

Clinical application and development of α-emitting radionuclides for targeted radionuclide therapy

核医学治療は，放射性医薬品を体内に投与して病巣に集積させ，集積した局所で放出される放射線により治療を行うものである。RI内用療法，内照射療法など，いくつかの呼称があるが，欧米ではtargeted radionuclide therapyが一般的であり，標的RI治療という呼び方が治療法をよく反映している。

Targeted radionuclide therapy（TRT）uses β or α-emitting radionuclide-labeled compounds that target cancer cells and remain sufficient time in the lesions for radiation to damage cancer. Recent clinical data using ²²⁵At-labeled compounds have been showing outstanding effectiveness for patients with neuroendocrine neoplasms and prostate cancer refractory to ¹⁷⁷Lu or ⁹⁰Y-labeled compounds. The scheme of future TRT is dosimetry-based therapy to establish effective dose to the targets, while securing permissible level of radiation to the risk organs like other radiation therapy. TRT works for multiple metastases and dissemination, in this sense, it has unique and complementary role in the radiation therapy.