Abstract
Introduction: Breast cancer is a complex and heterogeneous disease which is increasingly important as a public health problem. In Brazil, 57,960 new cases have been estimated to be the burden in 2016 and 2017. Despite advances in early diagnosis and therapy, approximately 20-30% of patients, even with early stage lesions, will develop distant metastatic disease. Tumors with similar clinical and pathological presentations may have differing behavior, so it is important to understand specific biological characteristics. Objective: To investigate tumor markers of primary tumors featuring pleural metastasis to identify organ-specific characteristics of metastatic breast cancer. Methods: In a historical cohort study, immunohistochemistry was performed on cell blocks of neoplastic pleural effusions and results were compared with clinicopathological data. Results: The median survival time with Her-2 overexpression in malignant pleural effusions was 2.2 months, whereas cases without overexpression survived, on average, for seven months (p = 0.02). Conclusions: We emphasize that metastases may behave independently of primary tumors, but the present results indicate that therapeutic agents targeting Her-2 overexpression could increase survival in metastatic breast cancer cases.