Effect of Neoadjuvant Therapy on the Functional Outcome of Patients With Rectal Cancer: A Systematic Review and Meta-Analysis

The impact of neoadjuvant therapy on the functional outcome of patients with resectable rectal cancer is still controversial. The aim of the present study was to explore the effects of neoadjuvant therapy on anorectal function (ARF), urinary function and sexual function in relevant patients.PubMed, Embase, Web of Science and the Cochrane Library were searched systematically. All English-language studies, published from January 2000 to July 2021, that explored the (postoperative) effects of neoadjuvant therapy versus upfront surgery on ARF, urinary function and sexual function of patients were included (PROSPERO 2021: CRD42021281617).The data in this study were derived from 37 articles based on 33 studies; in total, 17 917 patients were enrolled. The meta-analysis revealed that the incidence of anorectal dysfunction in the neoadjuvant therapy group was significantly higher than that in the group of upfront surgery, which was manifested by a higher incidence of major low anterior resection syndrome (odds ratio = 3.09, 95% confidence interval = 2.48, 3.84; P < 0.001), reduction of mean squeeze pressure and mean resting pressure, and other manifestations, including clustering of stools, incontinence, urgency and use of pads. With the extension of follow-up time, the adverse effects of neoadjuvant therapy on major low anterior resection syndrome existed. Compared with patients undergoing upfront surgery, neoadjuvant therapy increased the risk of urinary incontinence (odds ratio = 1.31, 95% confidence interval = 1.00, 1.72; P = 0.05) and erectile dysfunction (odds ratio = 1.77, 95% confidence interval = 1.27, 2.45; P < 0.001).Compared with upfront surgery, neoadjuvant therapy is not only associated with impairment of ARF, but also with increased incidence of urinary incontinence and male erectile dysfunction. However, the influence of confounding factors (e.g. surgical method, tumour stage) needs to be considered.