Secondary bladder cancer after permanent iodine-125 brachytherapy for prostate cancer

Bladder cancer has been observed in patients after permanent iodine-125 brachytherapy （hereafter referred to as brachytherapy） for prostate cancer. We investigated secondary bladder brachytherapy. From January 2005 March 2021, a total of 1,478 underwent localized at Showa University Hospital and Koto Toyosu Hospital. A standardized incidence rate was calculated from the compared with national registry general data. The median follow-up 4.7 years. Secondary occurred 15 1478 （median age: 71 years）. 198 cases/100,000 persons/year. 2.84 times higher than that Japan’s registry. In addition, characteristic cancer, malignancy tended be high regardless depth invasion. relative risk between cases period until occurrence ＞5 years ≤5 1.61 （95％ CI: 0.57-4.50）, but difference not significant. this study, we found population Japan, suggesting increases developing To our knowledge, study is first compare Japan. results suggest although effective attention should paid early detection because development.