Comparison of nodal positivity between SLNM vs conventional surgery in colon cancer patients with <12 and ≥12 lymph nodes harvested

Background: Examination of ≥12 lymph nodes (LNs) ensures accurate staging in colon cancer. The aim of this study was to compare nodal positivity between sentinel LN mapping (SLNM) and conventional surgery in patients with <12 and ≥12 LNs harvested. Methods: From 1993 to 2008, 407 and 380 patients with colon cancer underwent SLNM and conventional surgery, respectively. Total LNs harvested and nodal positivity were analyzed. Patients were grouped according to number of LNs harvested: 2 to 11, 12 to 25, or >25. Results: The average numbers of LNs harvested in the groups with 2 to 11, 12 to 25, and >25 LNs harvested for SLNM and conventional surgery, respectively, were 8.3 and 7.1 (P < .0001), 17.2 and 16.5 (P = .09), and 34.2 and 32.1 (P = .40). Nodal positivity for SLNM and conventional surgery in the groups with <12 and ≥12 LNs harvested was 42% and 29% (P = .01) and 50% and 36% (P = .003), respectively. Overall nodal positivity was 47% for SLNM and 32% for conventional surgery (P < .0001). When SLNM with 2 to 11 LNs was compared with conventional surgery with 12 to 25 LNs, nodal positivity was 42% versus 36% (P = .35). Conclusions: SLNM possessed higher nodal positivity compared with conventional surgery. SLNM is a valuable adjunct to accurate nodal staging in colon cancer.