D3 Lymph Node Dissection Improves Survival Outcomes in Patients With cT2 Colorectal Non-well-differentiated Adenocarcinoma

Background/Aim: The extent of lymphadenectomy appropriate for patients with cT2 colorectal cancer (CRC) remains controversial. This study was conducted to compare the survival outcomes of patients with cT2 CRC after D3 or D2 lymph node dissection (LND). Patients and Methods: Qualifying subjects (N=590) had undergone radical colorectal resections for cT2 CRC and were grouped according to tumor histological type as either well -differentiated (WDA) or nonwell -differentiated (nWDA) adenocarcinoma. Each group was further stratified into D3 or D2 LND according to the extent of lymph node dissection. Propensity score matching (PSM) was applied to balance potential confounding factors, and identify independent prognostic risk factors using 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 in 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. Conclusion: D3 LND improved survival outcomes in patients with non -well -differentiated cT2 CRC. In patients with well -differentiated cT2 adenocarcinoma, D3 LND was preferred to reduce perioperative complications.