To retrospectively investigate the relationship between metastatic lymph node ratio and prognosis in stage I~III colorectal cancer.

The clinicopathologic data of 446 patients with stage I~III colorectal cancer treated with curative resection at gastrointestinopancreatic surgery department of the First Affiliated Hospital of Sun Yat-sen University was retrospectively analyzed. Factors including metastatic lymph node ratio, pT stage, chemoradiotherapy, gender, age, histological grade, histological type and tumor size were univariate and multivariate analyzed to investigate the correlated prognostic risk factors in colorectal cancer.

Among the 446 colorectal cancer patients, the overall 5-year survival rates in NCCN stage I, II, III were 87.4%, 83.1%, 64.8% separately (P<0.001). For the rectal cancer subgroup, the overall 5-year survival rates in NCCN stage I, II, III were 86.5%, 73.7%, 56.2% separately (P<0.001). And for the colon cancer subgroup, the rates were 83.7%, 86.4% and 70.9% separately (P<0.001). When putting the patients into three groups according to the metastatic lymph node ratio (cutoffs 0, >0%~14%, >14%), we found an overall 5year survival rates of 81.8%, 77.7% and 57.2% separately (χ²=55.959, P<0.001) for the whole CRC patients. And the rates were 79.0%, 73.5% and 43.2% separately (χ²=26.332, P<0.001) for the rectal cancer subgroup and 87.1%, 80.8 and 55.5% separately (χ²=21.214, P<0.001) for the colon cancer subgroup. In univariate and multivariate analysis, metastatic lymph node ratio (mLNR) was found to be significantly associated with overall survival. The poor prognosis was associated with increasing mLNR. In the rectal cancer subgroup and colon cancer subgroup, similar results were achieved. mLNR is an independent prognostic factors for colorectal cancer.

Metastatic lymph node ratio (mLNR) is an independent prognostic factor of colorectal cancer patients. The mLNR classification in colorectal cancer is similar with the pN stage classification, but more precise, in the prognostic assessment.