Predictors of axillary lymph node metastases in early breast cancer and their applicability in clinical practice.

Purpose: Lymph node involvement is the most important prognostic factor in breast cancer. It is a multifactorial event determined by patient and tumour characteristics. The purpose of this study was to determine clinical and pathological factors predictive for axillary lymph node metastasis (ALNM) in patients with early breast cancer and to build a model to portend lymph node involvement.

Methods: We evaluated 1300 consecutive patients surgically treated in our institution (2007-2009) for cT1-T2 invasive breast cancer. The patient and tumour characteristics evaluated included: age at diagnosis, number of foci, histologic grade, location, tumour size, histologic subtype, lymphovascular invasion (LVI), estrogen-receptor (ER), progesterone-receptor (PR) and Her-2 status. Univariate and multivariate analyses were performed. Factors significantly associated with ALNM by univariate analysis plus histologic subtype were included in the multivariate analysis.

Results: By univariate analysis, the incidence of ALNM was significantly associated with the presence of LVI (P < 0.0001), larger tumour size (P < 0.0001), higher histologic grade (P < 0.0001), retroareolar or lateral location in the breast (P < 0.0001), multiple foci (P = 0.0002) and in patients who underwent an axillary lymph node dissection. We found no effect of age, ER⁄PR nor HER-2 status. By multivariate analysis, ALNM was significantly associated with the presence of LVI (P < 0.0001), larger tumour size (P < 0.0001), axillary lymph node dissection (P = 0.0003), retroareolar and lateral tumour location in the breast (P = 0.0019) and the presence of multiple foci (P = 0.0155).

Conclusions: LVI and tumour size emerged as the most powerful independent predictors of ALNM, followed by the location of the tumour in the breast and the presence of multiple foci.