Anorectal Function And Its Influencing Factors In Patients With Mid And Low Rectal Cancer Before And After Surgery—a Prospective Study

Background and Objective The quality of life(QOL) in patients with mid and low rectal cancer is seriously impaired with the occurrence of "anterior resection syndrome(ARS)" after surgery. In this prospective study, we aimed to evaluate the anorectal functions and its influencing factors before therapies and the effects of neoadjuvant chemoradiotherapy on anorectal functions, to follow-up the anorectal functions and QOL after surgery in patients with mid and low rectal cancer.Methods Patients diagnosed with mid and low rectal cancer in Peking Union Medical College Hospital from October2012to December2013were consecutive enrolled in this study. We surveyed the defecation symptoms by administration of a questionnaire in the face-to-face interview manner and detected the anorectal functions by three dimensional high resolution manometry system (3D HR-ARM) preoperatively. Patients were followed-up at6weeks after the end of neoadjuvant chemoradiotherapy to evaluate the effect of the therapy on anoractal functions before surgery, or at1,3and6months after radical surgery or colostomy movable surgery to demonstrate the outcome of ARS symptoms, anorectal functions and QOL after surgery. QOL was evaluated with QLQ-C30. The patients were divided as mid group and low group according to the distance from the distal margin of tumor to the anal margin.Results Of66patients before their surgery were enrolled in this study. Hematochezia is the most common symptom(95.5%), frequent bowel movement occured in50%patients, abnormal bowel forms, urgency, sensation of incomplete defecation, and tenesmus occurred in30.3%～40.9%of patients with mid and low rectal cancer. The occurrence of hematochezia, frequent bowel movement and sensation of incomplete defecation were negatively correlated with the tumor infiltration depth(P<0.05). The volume of desire to defecate and the maximum tolerated volume in3D HR-ARM were also negatively correlated with the tumor infiltration depth(P<0.01). More patients in low group had difficulties to defecate than in mid group(27.2%vs6.8%, P=0.031). Patients in low group had significantly lower anal mean resting pressure(MRP) than mid group[87.20(49.80)mmHg vs108.25(41.80)mmHg, P=0.017]. The rectal anal inhibitory reflex(RAIR) was observed in all the patients during3D HR-ARM. The volume of desire to defecate, the maximum tolerated volume were lower than the normal references[50.00(40.00)ml vs80-150ml;120.00(70.00)ml vs≥200ml]. The female patients had higher MRP than males[116.60(28.85)mmHg vs105.80(34.35)mmHg, P=0.016].Twenty two patients were followed-up for evaluation the effect of neoadjuvant chemoradiotherapy on anorectal function. The symptoms improved significantly after neoadjuvant chemoradiotherapy(21/22). Among those in low group (n=8), the length of high pressure zone in manometry increased significantly after neoadjuvant chemoradiotherapy(3.84±0.61vs2.96±0.80cm, P=0.003). Whether the defecation symptoms improved or not had no significant correlation with the length of the anal sphincter high pressure zone before neoadjuvant chemoradiotherapy.We followed-up36patients received rectal anterior resection, of which17had temporary bypass stoma. The number of bowel movement, fecal incontinence score decreased with times going. The low anterior resection syndrome score(LARS score) was lower at6months than at1month and at3months after surgery(28.47±12.75vs35.36±11.48, P=0.018;28.47±12.75vs34.17±12.26, P=0.050). There are23patients repeated3D HR-ARM between3～6months postoperation, MRP decreased comparing(?)with(?)that before-surgery(P<0.05); in patients who had neoadjuvant therapy before surgery(n=17), the length of high pressure zone, the maximum squeezing pressure and maximum tolerated volume decreased significantly after surgery(P<0.05). RAIR were observed only in one patient after surgery manometry. The focal defects of anal pressure were found in73.91%patients and the spastic peristalsis contractions in the segment of new rectum were observed in52.14%patients in3D HR-ARM after surgery. Patients with focal defects of anal pressure had higher scores of uncompleted defecation sensation, fecal incontinence and LARS. Patients with new rectal spastic peristalsis contractions had more frequent bowel movements, higher LARS score, and their defecation symptoms were more likely to be influenced by meal. In QOL, physical function, role function, social function, and general health scores gradually increased over time, which are correlated with the number of bowel movements, fecal incontinence score and LARS score.Conclusion In patients with mid and low rectal cancer, the infiltration depth and the distance from the distal margin of tumor to anal margin influence the anorectal functions, which characterized by decrease of anal mean resting pressure and damage of rectal sensory functions. The neoadjuvant chemoradiotherapy might improve the defecation symptoms for patients with mid and low rectal cancer and enhance anal sphincter high pressure zone for lower rectal cancer patients. In ARS, frequent bowel movements and fecal incontinence are the main symptoms to impair patients’ QOL after surgery. The damages of anorectal motility and sensory functions, especially the focal defects of anal pressure and the spastic peristalsis contraction from new rectum are the important pathphysiologic changes of ARS.