Lymph node ratio: a new feature for defining risk category of node-positive breast cancer patients.

St. Gallen 2005 expert consensus guideline modified its criteria for the risk category of breast cancer (BC) patients by integrating a combination of lymph nodes with metastasis (positive lymph nodes [PLNs]) and HER-2/neu status of tumor. Recently, some studies have shown that lymph node ratio (LNR), defined as the ratio of axillary lymph nodes with tumor metastasis to the total lymph nodes dissected, was a better independent prognostic indicator than PLN and should be considered as an alternative to the status of regional lymph nodes in the staging of breast cancer (pN). In the current study, the authors retrospectively reviewed 1095 primary BC patients with PLN and assessed the prognostic effect of LNR measured by relapse-free survival and overall survival to explore the feasibility of LNR and HER-2/neu status in stratifying the risk category of BC. Our results indicate that although by univariate analysis and when assessed as single covariate in multivariate analysis, both PLN and LNR were independent prognostic factors, PLN lost its significance when combined with LNR as covariates. A cutoff value of LNR = 0.30 was identified to show high accuracy in separating patients based on their survivals. The risk categories defined by LNR combined with HER-2/neu status were compatible to those defined by the PLN in combination with HER-2/neu status. LNR was a strong prognostic predictor of node-positive BC patients, superior to PLN. It should be considered as a new factor to couple with HER-2/neu status in defining risk category of BC patients.