POTENTIAL DISADVANTAGES OF POSTOPERATIVE ADJUVANT RADIOTHERAPY AFTER ANTERIOR RESECTION FOR RECTAL-CANCER - A PILOT-STUDY OF SPHINCTER FUNCTION, RECTAL CAPACITY AND CLINICAL OUTCOME

The aim of this study was to try to gauge the functional effect of pos t-operative adjuvant radiotherapy after potentially curative anterior resection for carcinoma of the rectum. Anorectal function was studied both in the laboratory and clinically in 59 patients, a median of 12 m onths (range 6-96) after operation. Nine patients received post-operat ive radiotherapy and 50 matched patients were treated by surgery alone . Though maximum resting anal pressures and maximum squeeze pressures were similar in the two groups of patients, the length and pressure pr ofile of the anal sphincter were both markedly abnormal after radiothe rapy. The capacity and compliance of the neorectum were diminished sig nificantly after radiotherapy (maximum tolerated volume 53 ml vs 110 m l after surgery alone, P=0.008, compliance 1.5 ml/cm H2O vs 3.7 ml/cm H2O after surgery alone, p=0.018) and the amount of distension of the neorectum required to produced maximum inhibition of the anal sphincte r during the rectoanal inhibitory reflex was also significantly dimini shed after radiotherapy (P=0.005). Clinical anorectal function was wor se among patients who had received radiotherapy, a greater proportion of whom experienced both urgency of defaecation and varying degrees of incontinence. Major faecal leakage necessitating the use of a pad was recorded in 3 of the 59 patients after radiotherapy (one of whom requ ired a permanent colostomy), but in only 5 of 50 patients after surger y alone.