Breast cancer subtypes can be determinant in the decision making process to avoid surgical axillary staging: A retrospective cohort study.

INTRODUCTION: The need for performing axillary lymph-node dissection in early breast cancer when the sentinel lymph node (SLN) is positive has been questioned in recent years. The purpose of this study was to identify a low-risk subgroup of early breast cancer patients in whom surgical axillary staging could be avoided, and to assess the probability of having a positive lymph-node (LN).

METHODS: We evaluated the cohort of 612 consecutive women affected by early breast cancer. We considered age, tumor size, histological grade, vascular invasion, lymphatic invasion and cancer subtype (Luminal A, Luminal B HER-2+, Luminal B HER-2-, HER-2+, and Triple Negative) as variables for univariate and multivariate analyses to assess probability of there being a positive SLN o nonsentinel lymph node (NSLN). Chi-square, Fisher's Exact test and Student's t tests were used to investigate the relationship between variables; whereas logit models were used to estimate and quantify the strength of the relationship among some covariates and SLN or the number of metastases.

RESULTS: A significant positive effect of vascular invasion and lymphatic invasion (odds ratios are 4 and 6), and a negative effect of TN (odds ratios is 10) were noted. With respect to positive NSLN, size alone has a significant (positive) effect on tumor presence, but focusing on the number of metastases, also age has a (negative) significant effect.

CONCLUSION: This work shows correlation between subtypes and the probability of having positive SLN. Patients not expressing vascular invasion, lymphatic invasion and, moreover, a triple-negative tumor subtype may be good candidates for breast conservative surgery without axillary surgical staging.