P53, Bcl-2 expression and cell proliferation in benign breast lesions.

The role of proliferation-related markers on breast cancer pathogenesis has been only occasionally investigated. The immunocytochemical expression of P53 and Bcl-2 (using PAb1801 and anti-bcl-2 monoclonal antibodies) and cell proliferation (evaluated as the H-3-thymidine labeling index [H-3-dT LI]) were determined on 62 benign breast lesions at different risk. Accumulation of the P53 protein was never observed; Bcl-2 was detected in 50% of cases and it was unrelated to biologic and clinicopathologic features. Median H-3-dT LI was about three times lower than that observed on large series of invasive breast cancer. It was only slightly higher in lesions from patients younger than 35 years or with a positive family history than in those under 35 or with a negative family history and appeared unrelated to histology or risk classification. Such findings indicate that the investigated biomarkers fail to identify women at increased risk for breast cancer.