Disruption of the balance between apoptosis and proliferation is considered to be an important factor in the development and progression of tumor. In this study we determined the in vivo cell kinetics along the spectrum of apparently normal epithelium, hyperplasia, preinvasive lesions and invasive carcinoma, in breast tissues affected by fibrocystic changes in which preinvasive and/or invasive lesions developed, as a model of breast carcinogenesis. Materials and method: A total of 32 areas of

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... parently normal epithelium and 135 ductal proliferative and neoplastic lesions were studied. More than one epithelial lesion per case was analyzed. The apoptotic index (AI) and the proliferative index (PI) were expressed as the percentage of TUNEL (TdT-mediated dUTP-nick end-labelling) and Ki-67 positive cells, respectively. The proliferative/apoptotic index (P/A) was calculated for each case. Results: Statistical analysis demonstrated significant differences among the tissue groups for both indices (P < 0.0001). The Als and PIs were significantly higher in hyperplasia than in apparently normal epithelium (P = 0.04 and P = 0.0005, respectively), in atypical hyperplasia than in hyperplasia (P = 0.01 and P = 0.04, respectively) and in invasive carcinoma than in in situ carcinoma (P = 0.0001 and P < 0.0001, respectively). The two indices were similar in atypical hyperplasia and in in situ carcinoma. The P/A index increased significantly from normal epithelium to hyperplasia (P = 0.01) and from preinvasive lesions to invasive carcinoma (P = 0.04), whereas it was decreased (NS) from hyperplasia to preinvasive lesions. A strong positive correlation between the Als and the Pls was found (r = 0.83; P < 0.0001). Conclusion: These findings suggest accelerating cell turnover along the continuum of breast carcinogenesis. Atypical hyperplasias and in situ carcinomas might be kinetically similar lesions. In the transition from normal epithelium to hyperplasia and from preinvasive lesions to invasive carcinoma, the net growth of epithelial cells results from a growth imbalance in favour of proliferation. In the transition from hyperplasia to preinvasive lesions there is an imbalance in favour of apoptosis. Objective: Denaturing high-performance liquid chromatography (DHPLC) is a recently developed method for detection of mutation that is gaining importance as a screening method for analyzing familial breast cancers, as well as heterogeneous tumor material. Method: DHPLC was established for mutation detection in BRCA1/2 diagnostic, using more than 200 different positive controls. Up until now, 64 DNA samples from patients with familial background for breast cancer (BC) were analyzed by DHPLC for BRCA1/2 mutations. An additional 136 sporadic BC were examined for p53 mutations, analyzing exons 5-8 by DHPLC. Positive results were confirmed by direct DNA sequencing. Results: The analysis of 64 DNA samples from patients with familial background for BC revealed several mutations and unclassified variants (UVs). Twenty-three different p53 mutations could be detected in 138 sporadic BC. Dilution of mutant DNA by wild-type DNA revealed the high sensitivity of this method: 5% mutant DNA is sufficient to achieve a positive DHPLC result. However, confirming a positive DHPLC result by DNA sequencing is difficult in heterogeneous tumor material. Conclusion: DHPLC is a reliable, high-throughput technique for detection of mutation in familial breast cancers, as well as in heterogeneous tumor material.