ACUTE EFFECTS OF THERAPEUTIC IRRADIATION FOR PROSTATIC-CARCINOMA ON ANORECTAL FUNCTION

Aims-The incidence of anorectal symptoms after radiotherapy (RTH) for localised pelvic malignant disease is unclear. In addition, the effect s of pelvic irradiation on both anorectal motility and sensory functio n are poorly defined. A prospective study was therefore performed on 3 5 patients (55-82 years of age) with localised prostatic carcinoma bef ore and four to six weeks after RTH to assess its effects on anorectal function. Methods-Anorectal symptoms were assessed by questionnaire. Anorectal pressures at rest and in response to voluntary squeeze, rect al distension, and increases in intra-abdominal pressure were evaluate d with perfused sleeve side hole manometry. Rectal sensation was teste d during graded balloon distension. Rectal compliance was calculated b y the pressure-volume relation obtained during the testing of rectal s ensation. Ultrasound was used to determine anal sphincter structure an d integrity. Results-RTH had no effect on anal sphincter morphology. T he frequency of defecation increased after RTH (7 (3-21) v 10 (3-56) b owel actions a week; p<0.01). After RTH, 16 patients had faecal urgenc y and eight faecal incontinence, compared with five and one respective ly before RTH (p<0.01 for each). Basal and squeeze sleeve recorded pre ssures were reduced after RTH (54 (3) v 49 (3) mm Hg (p<0.05) and 111 (8) v 102 (8) mm Hg (p<0.01), before and after RTH respectively; means (SEM)). Rectal compliance was reduced after RTH (1.2 v 1.4 mm Hg/ml, p<0.05). After RTH, threshold volumes for perception of rectal distens ion were lower in the 16 patients who either experienced faecal urgenc y for the first time (13 patients) or reported worsening of this sympt om (three patients) compared with the remaining patients (34 (4) v 48 (5) mi respectively, p<0.05). Conclusion-Faecal incontinence (23%) is a common problem four to six weeks after RTH for prostatic carcinoma a nd is associated with minor reductions in anal sphincter pressures, Th e high prevalence of faecal urgency in patients after RTH may be relat ed to alterations in rectal perception of stool.