Analysis on the correlation between number of lymph nodes examined and prognosis in patients with stage II colorectal cancer

Lymph nodes examined is important for N staging of colorectal cancer. There is no consensus on the optimal minimum number of lymph nodes for stage II colorectal cancer. This study was designed to determine the minimum number of lymph nodes and to identify the correlation between prognosis of stage II colorectal cancer and number of lymph nodes examined. Data of 729 patients with stage II colorectal cancer who underwent radical resection were studied retrospectively. The mean number of lymph nodes was 14.9 (range 1–58). Five-year survival rate was 76.8 %, and an average of 10.9 nodes was examined from deaths and 15.7 from survivors (P = 0.000). The difference of survival rates between patients with 13 or more nodes and less than 13 nodes was the most obvious (88.7 vs 64.9 %, P = 0.000). Thirteen was recommended as the minimum number of lymph nodes according to our results.