Résumé :
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[BDSP. Notice produite par INIST-CNRS 7R0xCCF8. Diffusion soumise à autorisation]. Etiologic differences between subtypes of breast cancer defined by estrogen receptor (ER) and progesterone receptor (PR) status are not well understood. The authors evaluated associations of hormone-related factors with breast cancer subtypes in a population-based case-control study involving 1,409 ER-positive (ER+)/PR-positive (PR+) cases, 712 ER-negative (ER-)/PR-negative (PR-) cases, 301 ER+/PR-cases, 254 ER-/PR+cases, and 3,474 controls aged 20-70 years in Shanghai, China (phase I, 1996-1998 ; phase II, 2002-2005). Polytomous logistic regression and Wald tests for heterogeneity across subtypes were conducted. Breast cancer risks associated with age at menarche, age at menopause, breastfeeding, age at first livebirth, waist-to-hip ratio, and oral contraceptive use did not differ by hormone receptor status. Among postmenopausal women, higher parity (>2 children vs. 1) was associated with reduced risk (odds ratio (OR)=0.69,95% confidence interval (CI) : 0.52,0.91) and higher body mass index (BMI ; weight (kg)/height (m) 2) with increased risk (highest quartile : OR=2.40,95% CI : 1.65,3.47) of the ER+/PR+subtype but was unrelated to the ER-/PR-subtype (for parity, Pheterogeneity=0.02 ; for BMI, Pheterogeneity
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