EFFECT OF PELVIC IRRADIATION ON GASTROINTESTINAL FUNCTION - A PROSPECTIVE LONGITUDINAL-STUDY

PURPOSE: Although radiation enteritis is a well-recognized sequel of therapeutic irradiation, the effects of abdominal and/or pelvic irradiation on gastrointestinal function are poorly dermed and treatment is often unsuccessful. To determine both the short- and long-term effects of therapeutic irradiation on gastrointestinal function, we performed a prospective study. PATIENTS AND METHODS: Various aspects of gastrointestinal function were evaluated in 27 patients with potentially curable malignant disease (23 female, 4 male) before the commencement of, during, and 6 to 8 weeks, 12 to 16 weeks, and 1 to 2 years following completion of radiation therapy. Seventeen patients received pelvic irradiation alone and 10 patients received both abdominal and pelvic irradiation. Gastrointestinal symptoms, absorption of bile acid, vitamin B12, lactose, and fat, gastric emptying, small-intestinal and whole-gut transit, stool weight, and intestinal permeability were measured. Results were compared with those obtained in 18 normal volunteers. RESULTS. All 27 patients completed at least 2 series of measurements and 18 patients completed all 5 series of experiments. During radiation treatment, increased stool frequency (p <0.001) was associated with decreased bile acid and vitamin B12 absorption (p <0.001 for both), increased fecal fat excretion (p <0.05), an increased prevalence of lactose malabsorption (p <0.01), and more rapid small-intestinal (p <0.01) and whole-gut (p <0.05) transit. Although there was improvement in most of these changes with time, at 1 to 2 years after the completion of irradiation, the frequency of bowel actions was greater (p <0.001), bile acid absorption was less (p <0.05), and small-intestinal transit was more rapid (p <0.01) when compared with that of baseline and the normal subjects. At this time, at least 1 parameter of gastrointestinal function was abnormal in 16 of the 18 patients. Stool weight was greater (p <0.05) and whole-gut transit faster (p <0.01) in patients who received both pelvic and abdominal irradiation, when compared with those who received pelvic irradiation alone. Stool frequency (p <0.001) and fecal fat excretion (p <0.05) were greater in those patients who had surgery before radiation therapy. CONCLUSION: Pelvic irradiation is usually associated with widespread, persistent effects on gastrointestinal function.