Acute effects of therapeutic irradiation for prostatic carcinoma on anorectal function

Aim—The incidence ofanorectal symptoms after radiotherapy (RTH) for localised pelvicmalignant disease is unclear. In addition, the effects of pelvicirradiation on both anorectal motility and sensory function are poorlydefined. A prospective study was therefore performed on 35 patients(55-82 years of age) with localised prostatic carcinoma before andfour to six weeks after RTH to assess its effects on anorectal function.
Methods—Anorectalsymptoms were assessed by questionnaire. Anorectal pressures at restand in response to voluntary squeeze, rectal distension, and increasesin intra-abdominal pressure were evaluated with perfused sleeve sidehole manometry. Rectal sensation was tested during graded balloondistension. Rectal compliance was calculated by the pressure-volumerelation obtained during the testing of rectal sensation. Ultrasoundwas used to determine anal sphincter structure and integrity.
Results—RTH had noeffect on anal sphincter morphology. The frequency of defecationincreased after RTH (7 (3-21) v 10 (3-56) bowel actions a week; p<0.01). After RTH, 16 patients had faecal urgency and eight faecal incontinence, compared with five and onerespectively before RTH (p<0.01 for each). Basal and squeeze sleeverecorded pressures 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 afterRTH 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 distension were lower in the 16 patients who either experienced faecal urgency for the first time(13 patients) or reported worsening of this symptom (three patients)compared with the remaining patients (34 (4)v 48 (5) ml respectively, p<0.05).
Conclusion—Faecalincontinence (23%) is a common problem four to six weeks after RTH forprostatic carcinoma and is associated with minor reductions in analsphincter pressures. The high prevalence of faecal urgency in patientsafter RTH may be related to alterations in rectal perception of stool.

Keywords:anorectal function; radiotherapy; motility; manometry; incontinence