OBJECTIVE: Assess the clinical relevance of micro metastasis in sentinel lymph nodes in the overall survival and disease free survival of 1,211 patients undergoing sentinel lymph node biopsy. METHODS: Retrospective cohort study including 1,211 patients undergoing consecutive SLB from 1998 to 2010. SLB were performed in patients with invasive carcinoma of the breast with clinically negative axilla. Age, tumor size, and histologic grades, estrogen and progesterone receptors expression, HER-2, lymphovascular invasion and size of metastases in lymph nodes were assessed. Tumor sizes were divided according to pathologic staging into pT1(< 2,0mm) and pT2(>2,0mm). Lymph nodes were classified as negative (pN0), positive with micro metastases with diameter ranging from 0,21mm to 2,0mm(pN1mi) and positive with macro metastases with diameter greater than 2,0mm(pN1). Statistical analyses were performed by the Likelihood ratio test or Chi-square test for insufficient samples between macro metastases and micro metastases in SLB. Time was considered in months and the overall follow-up time was 125 months and mean time was 65 months. Local regional and distant recurrences were considered as events for disease free survival and Kaplan-Meier survival functions were constructed, testing time between metastases sizes in SLB using the Log-rank test, with a significance level of 5%. RESULTS: Of the studied variables, lymphovascular invasion(p = 0,068) and local regional and distant metastases(p = 0,002) had a statistically significant association with overall survival. Tumor size(p = 0,016); lymph vascular invasion(p = 0,002) and metastases types in sentinel lymph node(p < 0,001) were associated to disease free survival. In the association tests with types of metastases in sentinel lymph node, the following were statistically significant: age(p = 0,004), tumor size(p < 0,001), lymph vascular invasion(p < 0,001) and local regional and distant recurrences. In the interim and final Cox regression analysis, macro metastases were the only statistically relevant factor for disease free survival(p < 0,001). CONCLUSION: The presence of micro metastases(pN1mi) in sentinel lymph node is associated to a prognosis similar to that of negative axilla patients(pN0), indicating that other risk factors for local regional and systemic recurrences should be taken into account. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-01-28.

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