Lateral Lymph Node Dissection Was Unnecessary for Low and Middle Rectal Cancer: a Systematic Review and Meta-analysis

There was significant controversy about whether lateral lymph node dissection (LLND) should be performed routinely during radical rectal cancer surgery. This study compared total mesorectal excision (TME) with or without LLND in low and middle rectal cancer. Our team retrieved data from Pubmed, EMBASE, Ovid, Web of Science, and the Cochrane Library from their incipience to Oct 1, 2021. We combined the statistics using the survival variables’ hazard ratio (HR). If the article only provided survival curves and delivered no HR value, we used a statistical method to extract logHR and standard errors for data estimation. A total of 33 studies were included in this study (26 cohort studies and 7 randomized controlled trials (RCTs). We found a statistically significant difference in the 5-year postoperative local recurrence rate between LLND + TME group patients (HR = 1.36, 95% CI: 1.07–1.73, p = 0.01); no statistically significant difference in 5-year postoperative overall survival (OS) (HR = 0.95, 95% CI: 0.85–1.06, p = 0.36) and recurrence-free survival (RFS) (HR = 1.13, 95% CI: 0.99–1.29, p = 0.08) between patients in the LLND + TME and TME groups; no statistically significant difference in 5-year OS and RFS between the LLND + TME and TME groups, regardless of preoperative lateral lymph node metastasis (LLNM). LLND + TME was associated with significantly longer operation time (WMD 92.29, 95% CI 82.29–102.28, p < 0.00001), more intraoperative blood loss (WMD 261.31, 95% CI 196.39–326.24, p < 0.00001), higher urinary dysfunction (OR = 2.15, 95% CI 1.16–3.96, P = 0.01), and sexual dysfunction (OR = 6.33, 95% CI 1.73–23.13, P = 0.005). Whereas anastomotic leakage (OR = 1.00, 95% CI 0.54–1.85, p = 0.99) and bowel obstruction (OR = 1.03, 95% CI 0.42–2.54, p = 0.95) were similar between the two groups. LLND did not improve the long-term prognosis of patients with rectal cancer, prolonged the duration of surgery, increased intraoperative bleeding, and led to a higher incidence of postoperative voiding disorders and sexual dysfunction.