Meta-analysis of survival and functional outcomes after total mesorectal excision with or without lateral pelvic lymph node dissection in rectal cancer surgery

Abstract

Background: To compare outcomes of total mesorectal excision with or without lateral pelvic lymph node dissection for the treatment of rectal cancer.

Methods: The electronic data sources were explored to capture all studies comparing total mesorectal excision with and without lateral pelvic lymph node dissection in patients undergoing operation for rectal cancer. Random effects modelling was utilized for the analyses. The uncertainties associated with varying follow-up periods among the included studies were resolved by analysis of time-to-event outcomes.

Results: Eighteen comparative studies enrolling 6,133 patients were eligible. No difference was found between the 2 groups in terms of overall survival (hazard ratio: 0.92, 95% confidence interval 0.77-1.10, P = .36, I² = 67%), overall survival at maximum follow-up (odds ratio: 1.02, 95% confidence interval 0.83-1.25, P = .86, I² = 22%), 5-year overall survival (odds ratio: 1.01, 95% confidence interval 0.78-1.30, P = .94, I² = 50%), disease-free survival (hazard ratio: 1.25, 95% confidence interval 0.87-1.82, P = .23, I² = 74%), disease-free survival at maximum follow-up (odds ratio 1.07, 95% confidence interval 0.88-1.31, P = .50, I² = 0%), 5-year disease-free survival (odds ratio: 1.07, 95% confidence interval 0.86-1.32, P = .54, I² = 0%), local recurrence (odds ratio: 1.01, 95% confidence interval 0.72-1.42, P = .97, I² = 34%), distant recurrence (odds ratio: 0.96, 95% confidence interval 0.62-1.46, P = .84, I² = 18%), and total recurrence (odds ratio: 0.97, 95% confidence interval 0.72-1.29, P = .82, I² = 0%). Total mesorectal excision with lateral pelvic lymph node dissection resulted in longer operative time (mean difference: 116.02, 95% confidence interval 89.20-142.83, P < .00001, I² = 68%) and higher risks of postoperative complications (odds ratio: 1.59, 95% confidence interval 1.14-2.24, P = .007, I² = 0%), urinary dysfunction (odds ratio: 6.66, 95% confidence interval 3.31-13.39, P < .00001, I² = 23%), and sexual dysfunction (odds ratio: 9.67, 95% confidence interval 2.38-39.26, P = .002; I² = 51%). The results remained consistent through separate analyses for randomized trials, observational studies, and patients with or without neoadjuvant chemoradiotherapy.

Conclusion: The available evidence suggests that lateral pelvic lymph node dissection results in greater postoperative morbidity, urinary dysfunction, and sexual dysfunction without improving recurrence and survival. Further evidence is needed from randomized controlled trials to enable experts in the nerve-sparing surgical experiences and neoadjuvant therapy experience to advise on the best treatment strategies for the management of rectal cancer patients including those with possible positive nodes on pretreatment imaging.