Clinical and manometric effects of combined external beam irradiation and brachytherapy for anal cancer

This study evaluates anorectal function after combined tele- and brachytherapy for anal cancer using manometric measurements and a standardized questionnaire. Eight patients received 44+/-3 Cy external beam radiation Followed by 20+/-4 Gy interstitial brachytherapy with iridium-192. Patients were examined 43 months (range 25-83) after therapy. Maximum anal basal pressure. squeeze pressure, and squeeze increment were significantly lower in patients (50, 163, 115 mmHg, respectively) than in control subjects (75, 285; 180 mmHg, respectively). Decreased anal elasticity was not observed. Anal prestretch "normalized" the contractility of the internal and external sphincter. Thus damage to the anal epithelium and hemorrhoidal cushions seems to be the most important mechanism explaining reduced anal closing pressure values. The rectoanal inhibitory reflex was observed in all but one patient. Rectal compliance was significantly reduced. Whereas all patients could retain a water filled rectal balloon until the maximum tolerable sensation level was reached, the rectal saline infusion test was strongly abnormal. Four patients were perfectly continent. Four patients were incontinent for gas and presented urgency in case of liquid stools with limited soiling occurring once weekly or less; three of them also had urgency for solids. Defecation frequency was increased but regular in most patients. Reduced anal closure together with reduced rectal compliance are at the basis of stool frequency, urgency and partial incontinence with occasional soiling. However, enough reserve sphincter function was maintained to preserve a clinically acceptable degree of anal continence in our patients.