Peri-treatment change of anorectal function in patients with rectal cancer after preoperative chemoradiotherapy

Preoperative chemoradiotherapy (PCRT) is a standard treatment for locally advanced rectal cancer. The influence of PCRT on anorectal function has not been objectively assessed. We evaluated the short-term influence of PCRT on anorectal function in patients with locally advanced rectal cancer using anorectal manometry. We included 310 patients with locally advanced mid and lower rectal cancer who underwent PCRT from 2012 to 2015. We compared anorectal function based on anorectal manometry between before and after PCRT according to tumor location, clinical T (cT) stage, and tumor response after PCRT. Lower rectal cancer was common in the cohort of 310 patients (n = 228, 73.5%). Sphincter length (p = 0.003) and maximal resting pressure (p < 0.001) increased and maximal tolerated volume (p = 0.036) decreased after PCRT regardless of tumor location. Maximal squeezing pressure and rectal compliance slightly decreased, without statistical significance. Changes in manometric parameters after PCRT were not associated with changes of cT stage after PCRT. However, minimal sensory volume (p = 0.042) and maximal tolerated volume (p = 0.025) increased significantly in 143 patients (46.1%) with changes in the distance of the cancer from the anal verge after PCRT. PCRT did not impair the overall short-term anorectal manometric parameters in patients with locally advanced rectal cancer. Further study is required to investigate postoperative anorectal function after sphincter-preserving surgery to evaluate the long-term effects of PCRT on anorectal function.