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

PURPOSE: Although radiation enteritis is a well-recognized sequel of t herapeutic irradiation, the effects of abdominal and/or pelvic irradia tion on gastrointestinal function are poorly dermed and treatment is o ften 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 gastroin testinal function were evaluated in 27 patients with potentially curab le malignant disease (23 female, 4 male) before the commencement of, d uring, and 6 to 8 weeks, 12 to 16 weeks, and 1 to 2 years following co mpletion of radiation therapy. Seventeen patients received pelvic irra diation alone and 10 patients received both abdominal and pelvic irrad iation. Gastrointestinal symptoms, absorption of bile acid, vitamin B1 2, lactose, and fat, gastric emptying, small-intestinal and whole-gut transit, stool weight, and intestinal permeability were measured. Resu lts were compared with those obtained in 18 normal volunteers. RESULTS . All 27 patients completed at least 2 series of measurements and 18 p atients completed all 5 series of experiments. During radiation treatm ent, increased stool frequency (p <0.001) was associated with decrease d bile acid and vitamin B12 absorption (p <0.001 for both), increased fecal fat excretion (p <0.05), an increased prevalence of lactose mala bsorption (p <0.01), and more rapid small-intestinal (p <0.01) and who le-gut (p <0.05) transit. Although there was improvement in most of th ese changes with time, at 1 to 2 years after the completion of irradia tion, 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 sub jects. 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 b oth pelvic and abdominal irradiation, when compared with those who rec eived pelvic irradiation alone. Stool frequency (p <0.001) and fecal f at excretion (p <0.05) were greater in those patients who had surgery before radiation therapy. CONCLUSION: Pelvic irradiation is usually as sociated with widespread, persistent effects on gastrointestinal funct ion.