D3 lymph node dissection improves the survival outcome in patients with pT2 colorectal cancer

Background The extent of lymphadenectomy in patients with pT2 colorectal cancer (CRC) remains controversial. This study aimed to elucidate the effects of D3 and D2 lymph node dissection (LND) on survival in patients diagnosed with pT2 CRC. Methods This was a retrospective cohort study from a high-volume cancer center in Japan. From April 2007 to December 2020, 6273 patients with primary CRC were included in the study; among these, 616 patients diagnosed with pT2 CRC underwent radical colorectal resection. Propensity score matching (PSM) was applied to balance potential confounding factors, and a total of 104 matched pairs were extracted from the entire cohort. Independent risk factors associated with prognosis were determined by Cox regression analysis. The main outcome measures were overall survival (OS) and cancer-specific survival (CSS). Results Before PSM, there was a statistically significant difference across the cohort in OS and CSS ( p = 0.000 and 0.013) between D3 and D2 LND groups; the estimated hazard ratio (HR) was 2.2 (95% confidence interval (CI), 1.1–4.4, p = 0.031) for OS in the D3 LND and 4.4 (95% CI, 1.7 to 11, p = 0.0027) for CSS ( p = 0.013). There was also a significant difference ( p = 0.024) in OS between the D3 and D2 LND groups in the matched cohort, with an estimated HR for OS of 3.3 (95% CI, 1.2 to 9.1, p = 0.024) and an estimated HR for CSS of 7.2 (95% CI, 1.6 to 33, p = 0.011). Conclusions D3 LND had a significant survival advantage in the treatment of pT2 CRC. The results of this study provide a theoretical basis for the application of D3 LND in radical surgery for preoperative T2 CRC.