Chronic effects of therapeutic irradiation for localized prostatic carcinoma on anorectal function

Purpose: To evaluate prospectively the prevalence and pathophysiology of an orectal dysfunction following radiation therapy (RTH) for localized carcino ma of the prostate. Methods and Materials: The following parameters of anorectal function were evaluated in each of 35 patients (aged 55-82 years) with localized prostati c carcinoma treated with RTH either to a dose of 55 Gy/20 fractions/4 weeks (18 patients) or 64 Gy/32 fractions/6.5 weeks (17 patients), before RTH an d 4-6 weeks and at a mean (+/- SD) of 1.4 (+/- 0.2) years after its complet ion: (1) anorectal symptoms (questionnaire), (2) anorectal pressures at res t and in response to voluntary squeeze and increases in intra-abdominal pre ssure (multiport anorectal manometry), (3) rectal sensation (balloon disten sion) and (4) anal sphincteric morphology (endoanal ultrasound). Results: All but 1 patient completed three series of measurements. RTH had no effect on anal sphincteric morphology. The increase in frequency of defe cation and fecal urgency and incontinence scores previously reported in the patients 4-6 weeks after RTH mere sustained 1 year later (p < 0.001, p < 0 .001, and p < 0.05, cf. baseline, respectively). At this time, 56% (19 of 3 4), 50% (17 of 34) and 26% (9 of 34) of the patients had increased frequenc y of defecation, fecal urgency, and incontinence, respectively. Decreases i n anal sphincteric pressures at rest and in response to voluntary squeeze r ecorded in the patients 3-6 weeks after RTH were not sustained 1 year later but the volumes of rectal distension associated with perception of the sti mulus and desire to defecate were lower compared with baseline volumes (p < 0.01 and p < 0.05, respectively), reflecting heightened rectal sensitivity in the patients. There was no difference in measurements between the two r adiation dose regimens. Univariate logistical regression analysis was perfo rmed on patients who had experienced increased symptom scores or decreases in recorded motor and sensory manometric parameters at 1 year, cf. baseline . The predictor variables used included individual patient tumor and treatm ent characteristics as well as individual patient symptom scores and parame ters of anorectal motor and sensory function at baseline and 4-6 weeks afte r RTH. The results of the univariate logistical regression analysis showed that (I) frequency of defecation at 4-6 weeks and (2) rectal volumes at bas eline both for (a) perception (p < 0.001) and (b) desire to defecate (p < 0 .001), predicted significantly for the patients who had symptoms and signs of anorectal dysfunction at 1 year. Individual patient tumor and treatment- related variables tested, in contrast, had no predictive significance. Conclusions: Anorectal symptoms following RTH for prostatic carcinoma are c ommon and persist at least until 1 year after its completion and are associ ated with objective evidence of heightened rectal sensitivity. (C) 2000 Els evier Science Inc.