HER-2/neu Expression in Primary Breast Cancer With Sentinel Lymph Node Metastasis

Background Amplification of the protein product of the HER-2/neu oncogene in primary breast cancer specimens is associated with an adverse prognosis. We hypothesized that overexpression of HER-2/neu would predict metastases to the sentinel lymph nodes (SLNs). Methods A retrospective review of a prospective nonrandomized evaluation of 1055 clinically node-negative breast cancer patients undergoing 1063 SLN biopsies was performed. HER-2/neu analysis was performed by immunohistochemistry and, in selected cases, by fluorescence in situ hybridization. Clinical, demographic, surgical, radiological, and pathologic data were analyzed by using generalized estimating equations logistic regression models. Results Two hundred thirty-two (23.6%) of 985 operations in which the SLN was found at operation resulted in positive nodes. In a multivariate analysis, size (P < .0001) and HER-2/neu overexpression (P = .026) were independent predictors of SLN metastasis. Conclusions Size is a known predictor of SLN metastasis in the modern SLN era, as it was in the pre-SLN eras. HER-2/neu was found to be significantly predictive of SLN metastasis in our study. We anticipate a future when even the relatively minor procedure of SLN biopsy might be avoided with the predictive information gained from studying the pathology and molecular markers of primary breast cancers.