The rays are aimed at the pelvic area. As radiation treatment progresses, it may cause patients to become very tired. Resting is important, but doctors usually advise patients to try to stay as active as they can. Patients may have diarrhea or frequent and uncomfortable urination. In addition, when patients receive external radiation therapy, it is common for the skin in the treated area to become red, dry, and tender.
Radiation therapy can also cause hair loss in the pelvic area.
The loss may be temporary or permanent, depending on the amount of radiation used. Radiation therapy causes impotence in some men. This does not occur as often with internal radiation therapy as with external radiation therapy, since internal radiation therapy is not as likely to damage the nerves that control erection. There is also a slight risk of long-term incontinence of urine and rectal problems with external radiation. Some patients receive both kinds of radiation therapy.