Impact of D3 lymph node dissection on survival for patients with T3 and T4 colon cancer

The clinical significance of D3 lymph node dissection for patients with colon cancer remains controversial. This study aims to clarify the impact of D3 lymph node dissection on survival in patients with colon cancer. This is a retrospective cohort study from a prospectively registered multi-institutional database of colorectal cancer in Japan. Propensity score matching method was applied to balance potential confounders of the treatment. A cohort of 10,098 patients who underwent radical colectomy for pT3 and pT4 colon cancer between 1985 and 1994 were identified. A total of 3,425 propensity score matched pairs were extracted from the entire cohort. The primary outcome measure was overall survival (OS). In the entire cohort, there was a statistically significant difference in overall survival (OS) between the patients who had D3 and D2 lymph node dissection (p = 0.00003). The estimated hazard ratio (HR) for OS of patients who had D3 versus D2 lymph node dissection was 0.827 (95 % confidence interval, 0.757 to 0.904). In the matched cohort, there was also a significant difference in OS between the two groups (p = 0.0001), and the estimated HR for OS was 0.814 (95 % confidence interval, 0.734 to 0.904). We found D3 lymph node dissection for pT3 and pT4 colon cancer to be associated with a significant survival advantage in a large-scale database, even after adjusting potential confounders of lymph node dissection. This finding may provide a rationale for D3 lymph node dissection in radical surgery for pT3 and pT4 colon cancer.