[Current Status and Prospects of RI Internal Therapy for Prostate Cancer]

Most castration-sensitive prostate cancers(CSPC)with metastases progress to castration-resistant prostate cancer(CRPC)within a few years. In recent years, upfront treatment with second-generation antiandrogens, novel hormonal agents (ARSIs)and taxanes, administered at the mCSPC stage, has been developed and the evidence of delaying the time to reach CRPC has been reported. However, once the disease progresses to CRPC, there are few treatment options and no effective treatment sequence has been established. Ra223 as radiotherapy for bone metastases in mCRPC treatment has shown prolonged survival benefits, similar to ARSI and taxane-based anticancer drugs, and is widely used in Japan. Recently, prostate-specific membrane antigen(PSMA)-lutetium therapy, in which PSMA is coupled to 177Lutetium and administered systemically, has been developed in Western countries for mCRPC expressing PSMA and is an effective RI therapy that reduces bone and visceral metastases. It is expected to be covered by health insurance in Japan in the near future and is expected to be a promising treatment for mCRPC.