Radiotherapy for prostate cancer is associated with an increased incidence of 
secondary bladder cancer (BC). We investigated the incidence, 
clinicopathological characteristics, and prognosis of BC after radiotherapy, 
surgical therapy, and primary androgen-deprivation therapy (ADT) for prostate 
cancer. This study included 1,334 Japanese patients with prostate cancer treated 
with radiotherapy (n=631), surgical therapy (n=437), and primary ADT (n=266). 
During the median follow-up period of 51.2, 44.8, and 45.5 months, secondary BC 
occurred in 14 (2.2%), 5 (1.1%), and 0 (0%) of patients with prostate cancer 
treated with radiotherapy, surgical therapy, and primary ADT, respectively. The 
10-year BC-free survival rate was 91.3% in the radiotherapy group, 97.4% in the 
surgical therapy group, and 100% in the primary ADT group. The rates of 
intravesical recurrence, progression to muscle-invasive BC, and BC-specific 
death might be higher in secondary BC after radiotherapy compared with after 
surgical therapy. There was a significant difference in the incidence of 
secondary BC among different therapeutic modalities for prostate cancer in 
Japanese men, indicating significantly lower comorbidity rates of secondary BC 
after primary ADT for prostate cancer compared with radiotherapy.