CHRONIC EFFECTS OF PELVIC RADIATION-THERAPY ON ANORECTAL FUNCTION

PURPOSE: The long-term effect of 4,500 cGy of preoperative radiation o n anorectal function has not been prospectively evaluated. METHODS: An al manometry was performed on 20 patients with rectal carcinoma before and four weeks after receiving 4,500 cGy of external radiotherapy. Fo ur patients underwent proctectomies, three died, and three refused fol low-up. Ten patients were available for long-term follow-up and underw ent anal manometry at 14 to 42 (average, 35.5) months after initial ra diotherapy. RESULTS: No significant difference in mean maximum squeeze or resting pressures was found after radiation therapy. The sphincter profile and minimum sensory threshold were unchanged. The rectoanal i nhibitory reflex was present in all patients. Nine patients reported n ormal anal function. One patient who was incontinent before treatment remained incontinent. CONCLUSION: Preoperative radiation therapy has a minimal chronic effect on anorectal function. Incontinence after sphi ncter-saving operations for rectal cancer should not be attributed to preoperative radiation therapy.