Prognostic significance of lateral lymph node dissection in node positive low rectal carcinoma

Purpose This study was performed to identify patients who would benefit from lateral lymph node (LLN) dissection for advanced low rectal carcinoma. Methods Clinical outcomes were retrospectively studied in 149 patients with node positive low rectal carcinoma undergoing LLN dissection according to LLN status: patients with (group II) or without positive LLNs (group I), and the number (≤3, >3), side (unilateral, bilateral), and site of positive LLNs. Results The overall 5-year survival rate was significantly worse in group II (36.2%) than that in group I (69.8%). The 5-year survival rate was significantly worse in patients with >3 positive LLNs, bilateral positive LLNs, and positive LLNs in both areas B and C (high-risk group) than that in patients with ≤3 positive LLNs, unilateral positive LLNs, and positive LLNs in either area B or C. The 5-year survival rate was significantly better in patients without any high-risk factors (54.2%, low-risk group II) than that in patients who belonged to the high-risk group (12.3%). There was no significant difference in 5-year survival rate between group I and low-risk group II. There were significantly more well and moderately differentiated adenocarcinoma, tumors with less than minimal lymphatic invasion, and tumors with less than six involved LNs in the mesorectum in low-risk group II than in high-risk group II. Conclusions LLN dissection for low rectal carcinoma was effective for patients with fewer than four positive unilateral LLNs in either area B or C.