In situ observation of apoptosis and proliferation in breast cancer and its precancerous lesions

OBJECTIVE: To investigate the effects of apoptosis and proliferation on malignant transformation of breast precancerous lesions by in situ observation. METHODS: The density and distribution of apoptotic cells were examined in 31 cases with breast cancer, 20 with dysplasia and 20 with hyperplasia, using TUNEL (TdT-mediated dUTP nick end labeling) technique and immunohistochemical method respectively. Eight normal breast tissues were used as the control. RESULTS: In normal breast tissue, apoptotic cells were located at the lacteals and gland follicles, facing the cavity. The proliferating cells were located at the basal layer of mucosa. These characteristics of distribution were lost in breast cancer and precancerous lesions. The density of apoptotic cells and proliferating cells of dysplasia was significantly higher than that in breast cancer and normal mucosa, The density of apoptotic cells and proliferating cells in breast cancer was significantly higher than that in normal mucosa. The ratio of apoptotic to proliferating cells in hyperplasia and dysplasia was 1:1.3-1.4, 1:1.1-1.2 respectively, and 1:2.3-2.4 in breast cancer. CONCLUSION: Abnormality in cell apoptosis and proliferation may play important role in the genesis of breast cancer.