Near-absolute expression of the bcl-2 protein identifies a subgroup of stage II breast cancer patients with a most favorable outcome. Results of a clinicopathological study.

The clinical relevance of quantitative assessment of tumor-tissue expression of the bcl-2 protein in operated stage II breast cancer was investigated in this study. Thirty-five cases were studied by immunohistochemistry for the expression of bcl-2 protein and analyzed for disease outcome. One fourth (25%) of the cases were negative and 57% demonstrated near-absolute expression of the bcl-2 protein. No association was found between immunohistochemical detection of the protein with age, hormonal receptor status and tumor grading other than between bcl-2 and estrogen receptor expression (p=0.01). An impressively positive impact of near-absolute expression of bcl-2 on clinical outcome was identified. Our results provide evidence that quantitative assessment of bcl-2 expression constitutes a new approach in early breast cancer with potential clinical implications. We consider that molecular sub-staging of patients with stage II breast cancer by level of bcl-2 expression provides additional important prognostic information and prompts for investigation of its clinical significance on the issue of adjuvant systemic therapy.