Effect of radiotherapy on anorectal function in patients with cervical cancer

The acute and long-term effects of pelvic radiation on defecation were studied.

Anorectal function was assessed based on manometry and subjective symptoms in 31 patients with cervical cancer treated by radiotherapy alone. Sixteen of 31 patients were examined periodically before, during, and after radiotherapy (early group). Fifteen others were examined more than six months after completion of radiotherapy (late group).

One-third of patients in both groups had symptoms, mainly diarrhea and increased stool frequency. Patients in the late group also suffered from disturbed gas-stool discrimination, urgency, a sense of residual stool, and soiling. Anal canal resting pressure was significantly higher after radiotherapy (47 +/- 15.5 mmHg) than before radiotherapy (36.3 +/- 12.5 mmHg; P < 0.05). The maximum tolerable volume decreased with radiation, from 163.3 +/- 45 before to 119.2 +/- 41.4 ml during, 112.7 +/- 36.6 ml immediately after, and 94.6 +/- 34.4 ml in the late group (P < 0.01). Rectal compliance also decreased over time and was lower in the early group (before, 5.7 +/- 1.3 ml/mmHg; P < 0.01; during, 4.6 +/- 2.2 ml/mmHg, P < 0.01; after, 3.7 +/- 1.4 ml/mmHg; P < 0.05) than the late group (2.1 +/- 1.5 ml/mmHg) and lower before than after in the early group (P < 0.01). Although rectal pressure initiating continuous desire to defecate did not change, the maximum tolerable pressure was significantly higher in the late group (81 +/- 19.5 mmHg) than during (59 +/- 16.8 mmHg) or after (59.9 +/- 16.9 mmHg) radiotherapy in the early group (P < 0.05).

Radiation reduces the capacity of the rectal reservoir, even in asymptomatic patients. These changes develop during radiotherapy and progress over time.