Basal-Like Breast Cancer: Update on Clinicopathologic, Immunohistochemical, and Molecular Features

Abstract

Context.—Basal-like breast carcinoma (BLBC) is a distinct molecular subtype of breast carcinoma identified through gene expression profiling studies. Objective.—To provide the clinical background, the histologic profile, and the immunohistochemical profile of these tumors and discuss the current knowledge of their molecular signature and their implications on targeted molecular therapy. Data Sources.—Data were obtained from review of the pertinent peer-reviewed literature. Conclusions.—Basal-like breast carcinomas are aggressive tumors with poor prognosis. Lack of targeted therapy makes their treatment a challenging task. Traditional chemotherapy is still associated with a high risk of relapse and death in a high percentage of patients. Platinum-based chemotherapy has been considered as a candidate for the treatment of BLBCs owing to their BRCA1 phenotype. Approximately 22% of patients treated with single-agent cisplatin show pathologic complete response, which is a comparable rate to that seen with nonplatinum agents. Antiangiogenic agents have been promising, but their currently demonstrated limited response is considered disappointing. Additionally, epidermal growth factor receptor was not shown to be a helpful target for BLBC. A recent study has shown that BLBC appears to be especially sensitive to MEK inhibitors, making it a promising therapeutic possibility. The list of new targets is still evolving and the “magic” therapeutic target is yet to be discovered.