D3 lymph node dissection improves survival outcomes in patients with cT2 colorectal non-well-differentiated adenocarcinoma

Abstract

Background: The extent of lymphadenectomy appropriate for patients with cT2 colorectal cancer (CRC) remains controversial. This study was conducted to compare survival outcome of patients with cT2 CRC after D3 or D2 lymph node dissection (LND). Methods: Qualifying subjects (N=590) had undergone radical colorectal resections for cT2 CRC and weregrouped by tumor histological type as either well-differentiated (WDA) or non-well-differentiated (nWDA) adenocarcinoma. Each group was further stratified as D3 or D2 LND, according to extent of lymph node dissection. Propensity score matching (PSM) was applied to balance potential confounding factors, identifying independent prognostic risk factors by Cox regression analysis. Primary outcome measures were overall survival (OS), cancer-specific survival (CSS) and relapse-free survival rate (RFS). Results: Prior to PSM, OS and CSS differed significantly (p=0.001 and p=0.021, respectively) for D3 and D2 LND subsets of the nWDA group. Estimated hazard ratios (HRs) for OS and CSS were 3 (95% confidence interval [CI]: 1.3-6.8; p=0.0084) and 3.2 (95% CI: 1-10; p=0.047), respectively in the D3 LND subset. After matching, significant differences in OS (p=0.007) and CSS (p=0.012) were also observed, with corresponding estimated HRs of 4 (95% CI: 1.2-14; p=0.028) and 16 (95% CI: 1.2-220; p=0.034). In the WDA group, D2 and D3 LND procedures displayed similar favorable prognoses before and after matching. Postoperative complications emerged as independent risk factors for prognosis in the WDA group of patients with cT2 CRC. Conclusions: D3 LND improved survival outcomes in patients with non-well-differentiated cT2 colorectal adenocarcinoma. In patients with well-differentiated cT2 adenocarcinoma, D3 LND was preferential to reduce perioperative complications.