Impact of radiotherapy on anorectal function in patients with rectal cancer following a watch and wait programme

To assess the long-term anorectal function in rectal cancer patients following a watch-and-wait policy after chemoradiotherapy and to investigate the dose-volume effects of radiotherapy on the anorectal function.

Thirty-three patients with primary rectal cancer who were treated with chemoradiotherapy and a watch-and-wait policy with minimum follow-up of 2  years were included. We assessed the anorectal function using anorectal manometry and patient reported outcomes (Vaizey and LARS score). Dose-volume histograms were calculated for the rectum and anal sphincter complex, and associations between the dose-volume parameters and anorectal function were assessed.

D_mean to the rectum and anal sphincter complex was 50.5 Gy and 44.7 Gy, respectively. After a median follow-up of 38 (range 23-116) months, 33.3% of the patients reported major LARS. Mean LARS score was 23.4 ± 11.3 and mean Vaizey score was 4.3 ± 4.1. The most frequent complaints were clustering of defaecation and faecal urgency. Trends towards a higher Vaizey and LARS score after higher anal sphincter complex dose were observed, although these associations were not statistically significant.

This is the first study to investigate the late dose-volume effects of radiotherapy specifically on the anorectal function in rectal cancer patients. One-third of the patients had major LARS and the most frequent reported complaints were clustering and faecal urgency. Additionally, we observed trends towards worse long-term anorectal function after higher anal sphincter complex radiotherapy dose. However, this should be evaluated on a larger scale. Future efforts to minimise the dose to the sphincters could possibly reduce the impact of radiotherapy on the anorectal function.