Distribution of lymph node metastases is an independent predictor of survival for sigmoid colon and rectal cancer

OBJECTIVE: This study evaluated the prognostic significance of the distribution of lymph node metastases (LND) in patients with colorectal cancer. BACKGROUND: The impact of the LND on survival in colorectal cancer is unknown. METHODS: A total of 1205 consecutive patients who underwent potentially curative surgery for sigmoid colon or rectal cancer with high ligation of the inferior mesenteric artery (IMA) from January 1997 to February 2008 were assigned to 4 groups based on LND: LND0, no lymph node metastases-615 patients (51.0%); LND1, metastases in the pericolic nodes-324 patients (26.9%); LND2, metastases in the intermediate nodes-172 patients (14.3%); and LND3, node metastases at the origin of the IMA-94 patients (7.8%). RESULTS: The 5-year overall survival rates of patients with LND0, LND1, LND2, and LND3 were 83%, 63%, 52%, and 28%, respectively (P < 0.001). The 5-year disease-free survival rates of patients with LND0, LND1, LND2, and LND3 were 83%, 54%, 43%, and 21%, respectively (P < 0.001). On multivariate analysis, LND was an independent prognostic factor for both overall survival and disease-free survival. However, the 5-year local recurrence-free survival rate was not inversely related to the LND. On a subset analysis that compared stage III disease with stage IV disease, the 5-year overall survival and disease-free survival rates were 45% and 31% for the patients with stage IV disease compared with 40% and 32% for the patients with stage III, LND3 disease, respectively (P = 0.761 and 0.704). For the patients with pN1 tumors, the overall survival and disease-free survival did not differ significantly according to the LND (P = 0.471 and 0.347, respectively). However, for patients with pN2 tumors, the overall survival and disease-free survival curves among the LND groups significantly differed (P < 0.001 and <0.001, respectively). CONCLUSION: LND is an independent predictor of survival for colorectal cancer patients, but it does not predict local recurrence. The N categorization including LND may enhance the prognostic value of the TNM staging system for patients with node-positive sigmoid colon or rectal cancer.