Abstract 655: Menopausal hormone therapy and breast cancer risk: The CECILE Study

Abstract

Abstract Breast cancer in post-menopausal women has been associated with the use of menopausal hormone therapy (MHT). Estrogen-only (EO) and combined estrogen-progestagen (EP) therapies have been evaluated as potentially carcinogenic to human by the IARC. However, the type of estrogen and progestagen in the MHT varies considerably by country. For example, besides synthetic progestagens, the use of natural progesterone in combined EP therapy is specific to France. We investigated whether the association between MHT and breast cancer in postmenopausal women differ by type of chemical compound. We conducted a population-based case-control study in France in 762 cases and 840 controls recruited among postmenopausal women in two French “départements”. Data were collected including name of medication, date of start and end of each medication used. Unconditional logistic regression models were used, with adjustment for age, study area, and known risk factors for breast cancer. We observed a significant increased risk of breast cancer for current users of estrogen plus synthetic progestagen while no association was found for any use of estrogen-only therapy or combined therapy of estrogen plus natural progesterone. Among current users of estrogen plus synthetic progestagen, the association with breast cancer increased with duration of use and was higher in women who started their treatment before or shortly after menopause. Our study suggests that the use of natural progesterone as the progestagen component in a combined EP therapy is not associated with an increased risk of breast cancer. This result reinforces the findings reported in another cohort study of French women (E3N). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 655. doi:1538-7445.AM2012-655