Invasive bladder cancer following 125iodine implants.

We present 2 cases of invasive transitional cell carcinoma of the bladder following implantation of 125iodine seeds for the treatment of localized adenocarcinoma of the prostate. These tumors, which occurred approximately 6 years after radiotherapy, were located in the trigone and prostatic urethra within the previous radiation treatment field. The development of high grade transitional cell carcinoma in these patients may be due to the tumorigenic effects of 125iodine radiation.