The main possible complications of external radiotherapy include: 1. urinary side effects, such as urethral stenosis, bladder fistula, hemorrhagic cystitis, hematuria, etc.; 2. gastrointestinal side effects, such as enteritis, rectal bleeding, small bowel obstruction, etc.; 3. acute cutaneous side effects of radioactivity: erythema, skin dryness, and desquamation; and 4. other side effects: pubic and soft-tissue necrosis, and edema of the lower extremities, scrotum, or penis. It should be emphasized that most of these complications occur with conventional radiotherapy, and the incidence of conformal radiotherapy, which is now widely used, has been reduced to a very low rate. In addition radiotherapy may increase the risk of rectal and bladder cancer.