Bcl-2 is a highly significant prognostic marker of hormone-receptor-positive, human epidermal growth factor receptor-2-negative breast cancer

BaEurocell lymphomaaEuro2 (BclaEuro2) is one of the most important antiaEuroapoptotic genes. Although Bcl-2 promotes tumor cell survival in vitro, previous studies have shown conflicting results regarding the association between Bcl-2 and breast cancer survival. The aim of this study was to assess the prognostic significance of Bcl-2 according to the molecular tumor subtype in primary invasive breast cancer patients. The relationship between immunohistochemical Bcl-2 expression and overall survival was analyzed in 2399 primary invasive breast cancer patients treated by curative surgery. Patients were classified into four subtypes based on hormone receptor (HR) and human epidermal growth factor receptoraEuro2 (HER2) status: HR+/HER2-, HR+/HER2+, HR-/HER2+, and HR-/HER2-. A total of 1304 patients (54.4 %) had BclaEuro2 positive (+) tumors by immunohistochemistry. BclaEuro2 (+) tumors were significantly associated with a younger age (< 50 years), early stage, lower grade, positive expression of HR, and negative expression of HER2. In the HR+/HER2- group, patients with BclaEuro2 (+) tumors showed a significantly better prognosis (p < 0.001). In contrast, there was no significant prognostic effect of BclaEuro2 expression in other subtypes. In multivariate analysis, BclaEuro2 positivity remained an independent, favorable prognostic factor in the HR+/HER2- subtype (hazard ratio, 0.609; 95 % confidence interval, 0.424-0.874; p < 0.007). The prognostic significance of BclaEuro2 expression differed according to the molecular subtype of breast cancer. The expression of BclaEuro2 was an independent, favorable prognostic factor in breast cancer patients with the HR+/HER2- subtype.