The main side effects of external beam radiation for prostate cancer are injury to the bladder and rectum and ED.
Both during and after treatment, side effects may include frequent urination, urge incontinence (feeling like you have to urinate all the time), burning sensation while urinating, and blood in the urine. Less than 5% of men report problems with urinary incontinence in the first 5 years after treatment. But this may increase over time because the chances of having side effects after radiation go up each year after treatment. Side effects of external beam radiation may include diarrhea, blood in the stool, and colitis (irritated intestines). Occasionally, normal bowel function does not return after treatment is completed. The newer conformal radiation techniques may be less likely to cause bladder and bowel side effects.
About 30% to 70% of men who receive external beam radiation develop ED. This side effect usually does not occur right after radiation therapy, but gradually develops over one or more years. The long term rate of ED is similar to that associated with surgery. As with surgery, the older the man is, the more likely it is he will acquire ED. Impotence may be helped by treatments such as those listed earlier, including PDF inhibitors.
Brachytherapy may also result in ED, urinary incontinence, and bowel problems. Significant rectal problems (burning, pain, and diarrhea) may occur in approximately 5% of patients and are difficult to treat once they develop. While about one-third of men may have frequent urination, severe incontinence is not common. But as with external beam radiation, side effects may worsen several years after treatment. ED may be less likely to develop after brachytherapy than external radiation initially, but this problem can also increase over time.
Radiation therapy may also cause fatigue (feeling tired), which may persist for a few months after treatment stops.
