Nodal stage of stage III colon cancer: the impact of metastatic lymph node ratio.

Purpose: We assessed which classification of lymph node metastasis better predicted outcomes in patients with colorectal carcinoma.

Methods: We identified 318 patients (176 men) with stage III colon cancer who underwent curative resection. The number of LNs dissected, LNR, and disease-free survival time, were analyzed. Lymph node disease was stratified by the American Joint Committee on Cancer staging and LNR, with the latter categorized into groups with LNR <0.059 (n = 67), 0.059-0.23 (n = 171), and >0.23 (n = 80). Median follow-up time was 37 (range, 1-122) months.

Results: LNR significantly increased with the number of metastatic LNs (P < 0.0001). Three-year disease-free survival (DFS) rates differed significantly in the three LNR groups. Within each TNM stage, 3-year DFS rates differed according to LNR, but, within each LNR subgroup, 3-year DFS did not differ according to TNM stage. When both TNM stage and LNR subgroup were considered, 3-year DFS was stratified into four groups, which differed significantly (P < 0.0001). Considering number of retrieved lymph nodes, this stratification was not found when <12 lymph nodes retrieved.

Conclusions: Re-stratified lymph node staging, reflecting both LNR and TNM stage, can predict survival in patients with LN-positive colon cancer, especially when more than 12 lymph nodes harvested.