Lateral lymph node dissection reduces local recurrence of locally advanced lower rectal cancer in the absence of preoperative neoadjuvant chemoradiotherapy: a systematic review and meta-analysis

Background: The impact of lateral lymph node dissection (LLND) in locally advanced lower rectal cancer remains controversial. This study is to compare total mesorectal excision (TME) with or without LLND in lower rectal cancer cases of stage II/III. Methods: The electronic databases were systematically searched that compared TME with or without LLND among patients with lower rectal cancer in clinical stage II/III. Subgroup analysis was performed considering neoadjuvant chemoradiotherapy (nCRT). The hazard ratios (HR), relative risk (RR), and weighted mean difference (WMD) were pooled. Results: Twelve studies of 4458 patients of this meta-analysis demonstrate, LLND alone significantly reduced the local recurrence rate of patients who did not receive nCRT (RR 0.71, P = 0.004), while the difference was not significant when combined with nCRT (RR 0.70, P = 0.36). The analysis shows TME with LLND was associated with significantly longer operation time (WMD 90.73 min, P < 0.001), more intraoperative blood loss (WMD 303.20 mL, P < 0.001), and postoperative complications (RR = 1.35, P =0.02). Whereas urinary dysfunction (RR 1.44, P = 0.38), sexual dysfunction (RR 1.41, P = 0.17), and postoperative mortality (RR = 1.52, P = 0.70), were similar between these two groups. Statistically, no significant differences were observed in OS (HR 0.93, P = 0.62), DFS (HR 0.99, P = 0.96), total recurrence (RR 0.98, P = 0.83), lateral recurrence (RR 0.49, P = 0.14), or distal recurrence (RR 0.95, P = 0.78) between these two groups regardless of whether nCRT was performed or not. Conclusions: The study shows LLND alone decreases the local recurrence without using nCRT irrespective of the survival advantage in locally advanced lower rectal cancer. The benefit of controlling local recurrence by LLND alone makes us reconsider the usage of nCRT with LLND.