Prognostic role of micrometastases in sentinel lymph node in patients with invasive breast cancer

Background and Purpose of the study: Axillary lymph node status at the time of diagnosis remains one of the most important prognostic factors in women with breast cancer. Sentinel lymph node biopsy (SLNB) proved to be a reliable method for the evaluation of axillary nodal status in early-stage invasive breast cancer. The prognostic value and potential therapeutic consequences of SLN micrometastases remains a matter of great debate. Patients and Methods: From January 1998 to March 2011, 1,976 consecutive patients with non-metastatic invasive breast cancer underwent surgical treatment; 1,080 of them (54.6%) underwent SLNB. We collected data regarding demography, preoperative lymphoscintigraphy, type of surgery, histopathologic and immunohistochemical features and adjuvant treatment. Main findings: A mean number of 2.1±1.4 (range 1-13) SLN per patient were collected, a total of 2,294 nodes. SLNs were macrometastatic in 16.7% of patients and micrometastatic in 3.3%. Among the patients with positive SLN 93.6% underwent complete ALND. The overall survival (OS) and disease-free survival (DFS) of 72 patients with micrometastases in SLN at 60 months was 100%, similar to patients with negative SLN (98.7%), quite different from the DFS of N1-N3 patients (85.8%). Statistically significant differences in OS and DFS were observed between patients with N1mi and the group with N1-N3 sentinel node (p < 0.001 and p = 0.04) and also between patients with negative SLN and those with macrometastatic SLN (p < 0.001 for both). Conclusion: SLN micrometastases could represents an epiphenomenon of peritumoral lymphovascular invasion which impacts independently on the survival of patients with invasive breast cancer.