Bcl-2 protein expression in breast cancer and its relationship to prognosis

The expression of bcl-2 protein was studied in invasive breast cancer by immunohistochemistry. Fourty-six (56.8%) bcl-2 protein-positive tumors were found in 81 breast cancers. There was no significant correlation between the bcl-2 protein immunoreactivity and histologic type, primary tumor status, or lymph node metastasis. However, a strong positive relationship was demonstrated between bcl-2 immunoreactivity and estrogen receptor status. The 5-year survival rate and disease-free survival rates were 73.7% and 71.1% of patients with bcl-2-positive tumors, and 62.5% and 58.0% of those with bcl-2-negative tumors; these differences between the two groups of patients wete significant (p<0.05). In multivariate analysis using Cox regression model, bcl-2 immunoreactivity emerged as an independent prognostic indicator in breast cancer patients.