Predicting the status of axillary sentinel lymph nodes in 4351 patients with invasive breast carcinoma treated in a single institution

BACKGROUND. Reliable predictors of metastatic involvement would enable a better selection of candidate patients for sentinel lymph node biopsy (SLNB) and possibly allow identification of patients with such a low risk of axillary sentinel lymph node (SLN) involvement to be even spared SLNB. METHODS. The authors evaluated 4351 consecutive patients surgically treated for breast carcinoma who also underwent SLNB. Clinicopathologic features significantly associated with SLN metastases by univariate analysis were included in a multivariate model. RESULTS. By multivariate analysis, the prevalence of SLN metastases was associated directly with tumor size, multifocality, and with the occurrence of peritumoral vascular invasion (PVI; all P < 0.0001), and was associated inversely with a favorable histotype (P = 0.0007) and lack of progesterone receptors (P = 0.004). A predictive model based on the features more closely associated with SLN status documented that the patients with a favorable tumor type less than or equal to 1 cm in size and without PVI (n = 178 [4% of the population]) had the lowest risk of SLN metastases (9.5%) whereas patients with tumors > 2 cm and with PVI (n = 250 [5.7% of the population]) had the highest risk (77.2%) of SLN involvement. CONCLUSIONS. Tumor size and PVI emerged as the most powerful independent predictors of SLN metastases. Although no combination of features identified patients with a < 9.5% risk of SLN metastases, the current data may be used to tailor the management of patients with breast carcinoma with the aim of minimizing as much as possible the diagnostic and therapeutic procedures, thus improving the quality of life of the patients without any adverse effect on their survival rates.