Breast cancer and hormonal therapy in postmenopausal women

Letter to the editorsChlebowski et al. recently reported from the Women's Health Initiative (WHI) that the risk of breast cancer associated with the use of combined menopausal hormone therapy (HT) markedly decreased after treatment discontinuation. 1 With a similar approach to that used in the WHI observational-study cohort, we investigated whether that decrease was also seen in the French E3N cohort, in which HT use was biennially self-reported. 2 Among postmenopausal respondents to the 1997-1998 questionnaire, those who were using combined HT or had never used HT at completion of the questionnaire were followed from January 1999 up to the date of diagnosis of any malignancy, last completed questionnaire, or July 2005, whichever occurred first. Hazard ratios of breast cancer for combined HT users vs. HT never-users (in 1997-1998) dramatically dropped towards unity after 2002, in parallel with an important reduction in HT use (Table 1). Our results in a French population therefore corroborate those from the North-American WHI setting and strengthen suggestions of a marked and rapid decline of breast cancer risk after discontinuation of combined HT