Anorectal Function and Its Influencing Factors in Patients with Mid and Low Rectal Cancer

  Objective  To evaluate the anorectal function and its influencing factors in patients with mid and low rectal cancer.

  Methods  Patients diagnosed with mid and low rectal cancer in Peking Union Medical College Hospital from September 2012 to November 2013 were consecutively enrolled in this study. We surveyed the defecation symptoms based on a questionnaire in the face-to-face interview manner and detected the anorectal functions using three-dimensional high-resolution manometry system. The patients were divided into mid and low groups according to the distance from the distal margin of tumor to the anal margin.

  Results  A total of 66 patients were enrolled in this study, including 45 males and 21 females, with a mean age of (58.86±10.99) years. There were 44 patients in the mid group and 22 patients in the low group. Hematochezia was the most commonsymptom (95.5%), frequent bowel movement occurred in 50.0% patients, abnormal bowel forms, urgency, sensation of incomplete defecation, and tenesmus occurred in 30.3%-40.9% of the patients. The occurrences of hematochezia, frequent bowel movement and sensation of incomplete defecation were positively correlated with the depth of tumor infiltration (r=0.308, P=0.012; r=0.290, P=0.018; r=0.305, P=0.013). The rectoanal inhibitory reflex was preserved in all the patients. The volume of constant desire to defecate and the maximum tolerated volume were both lower than the normal references, and both negatively correlated with the depth of tumor infiltration (r=-0.333, P=0.007; r=-0.323, P=0.009). Compared with the mid group, the low group had a higher percentage of patients with difficulties to defecate (27.2% vs. 6.8%, P=0.031), and a significantly lower mean anal resting pressure87.20(49.80)mmHg vs. 108.25(41.80)mmHg, P=0.017.

  Conclusions  Mid and low rectal cancer patients manifest with various bowel symptoms with no specificity, except for hematochezia. Patients with mid and low rectal cancer have obviously impaired rectal sensory function. Their anorectal sensory and dynamic functions are influenced by the depth of tumor infiltration and distance from the distal margin of tumor to anal margin.