In response to Dr. Vordermark

Abstract

Although only rectal sensory changes persisted in the patients 1 year after completion of radiation therapy (RTh) for carcinoma of the prostate, we did not mean to imply that anal sphincteric dysfunction was not important in the pathogenesis of anorectal symptoms such as fecal incontinence. The subgroup analysis presented in the first paragraph, p. 921 of our paper, which indicated that fecal incontinence score was inversely related to basal anal pressures and anal pressures in response to squeeze in patients with persistent anorectal symptoms at 1 year compared with the remainder of the group, is evidence that dysfunction of the anal sphincters exists in these patients. However, the reductions in these parameters of anorectal motor function were overwhelmed by changes in the remainder of the group. As discussed in p. 923 of our paper, it is also possible that other motor events, such as transient internal anal sphincter relaxations (Ref. 25 in the paper), which are not detected by short-term ano-manometric studies, may be important etiologically. Prolonged recordings of anal sphincteric activity have revealed substantial variability in anal sphincter pressure (1), including transient internal anal sphincter relaxations, which are more common and more prolonged in incontinent compared with normal subjects. The rectum also shows periodic contractions, termed the rectal motor complex (2). These contractions often exceed resting anal pressure (3), but whether compensatory anal sphincter contractions occur in association with the rectal contractions is unclear. The evaluation of these periodic motor events in the pathogenesis of anorectal symptoms including fecal incontinence require long-term, preferably ambulatory, recordings of anorectal motor function (4). Until these studies have been performed, insights into the pathophysiology of anorectal dysfunction following RTh will remain limited. However, based on existing information, it is clear that the pathophysiology of anorectal sequelae of RTh is multifactorial. In support of this, we now have data to show that rectal compliance is also reduced 1 year after RTh for prostatic carcinoma (5), albeit based on a new cohort of patients who have been recruited since publication of our report (rectal compliance data for the first 35 patients were not published beyond 4–6 weeks after RTh (Ref. 3 in paper), because a change in catheter design soon after this time meant that pressures in response to rectal distension could not be measured at the same points 1 year later). The presence of multiple abnormalities in anorectal function in the patients 1 year after RTh for carcinoma of the prostate is consistent with findings in our previous study involving patients treated for gynecologic cancer (Ref. 12 in paper).