Résumé :
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[BDSP. Notice produite par INIST kqbfR0x0. Diffusion soumise à autorisation]. To investigate whether breast tumors developing through a pathway with p53 protein overexpression (p53+) show different risk factor associations compared with breast tumors without p53 overexpression (p53-), the authors determined p53 overexpression in tissue sections of 528 patients with invasive breast cancer by using immunohistochemistry. These patients and 918 healthy controls aged 20-54 years participated in a Netherlands population-based case-control study on oral contraceptives in 1986-1989. A total of 142 tumors (27%) demonstrated clear p53 overexpression (p53+). Most risk factors did not show different associations with p53+and p53-tumors. However, use of oral contraceptives for 9 or more years was associated with a 2.5-fold increase in the risk of p53+tumors (95% confidence interval 1.4-4.4 ; test for trend with months of use, p=0.01), whereas such use increased the risk of p53-tumors only 1.4-fold (95% confidence interval 0.9-2.1 ; test for trend, p=0.06). Prolonged lactation ( 25 weeks) was associated with a 40% reduction in risk of p53+tumors (odds ratio=0.6 ; 95% confidence interval 0.3-1.0 ; test for trend with weeks of lactation, p=0.09), whereas the risk of p53-tumors was not associated with lactation. (...)
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