Can axillary lymphadenectomy be avoided in breast cancer with positive sentinel lymph node biopsy? Predictors of non-sentinel lymph node metastasis

Purpose Completion axillary lymph node dissection (cALND) can currently be avoided in those patients with a low tumor load (LTL) and/or a low-risk profile that tested with positive sentinel lymph node biopsy (SLNB). Our objective is to identify prognostic factors that significantly influence axillary lymph node involvement to identify patients who could benefit from surgery without axillary lymphadenectomy. Methods This is an observational retrospective study of consecutive patients diagnosed and operated of breast cancer between 2000 and 2014 at University Hospital La Ribera (UHR). Results The size of the sample was 1641 patients, from which 1174 underwent SLNB. In the multivariate analysis, we objectify a raise of risk of positive sentinel lymph node (SLN) up to 5.2% for every millimeter of increase. The risk of positive SLNB when showing lymphovascular invasion seems to be 2.80 times greater but becomes lower when SLN involvement appears in luminal A, luminal B and triple-negative types, regarding HER2. In case of triple negatives, the difference is statistically significant. 16.7% present affected additional lymph nodes. The proportion of patients with affected additional lymph nodes increase dramatically above OSNA values of 12,000 copies/μl of CK19 mRNA and it depends on tumor size and lymphovascular infiltration. Conclusions Tumors smaller than 5 cm whose OSNA SLNB analysis is less than 12,000 copies/μl of CK19 mRNA have a low chance to develop additional affected lymph nodes, thus cALND can be avoided.