The above picture is the before and after of the treatment of a low grade bladder cancer.
The bladder is commonly in the path of the radiation and radiation cystitis occurs commonly.
There is a small incidence of bladder cancer after radiation of the prostate, but it occurs and should be part of the decision making process.
Patient’s will often question getting “a cancer” from having a CT scan (i.e. how much radiation is in this x-ray) and at the same time not think twice about receiving a full course of radiation to treat their prostate cancer. (External beam radiation is 42 treatments.)
In the case of radiation for prostate cancer the primary other organ in the treatment path is the bladder and the colon/rectum.
Not saying not to choose this form of treatment, but just like surgery you need to know all the facts.