title: Menopausal hormone therapy use and breast cancer risk in Australia: Findings from the New South Wales Cancer, Lifestyle and Evaluation of Risk study.
abstract: Randomised controlled trials and large-scale observational studies have found that current use of menopausal hormone therapy (MHT) is associated with an increased risk of breast cancer; this risk is higher for oestrogen-progestagen combination therapy than for oestrogen-only therapy. Our study was designed to estimate MHT-associated breast cancer risk in a population of Australian women. Data were analysed for postmenopausal women with self-reported incident invasive breast cancer (n = 1,236) and cancer-free controls (n = 862), recruited between 2006 and 2014 into a large case-control study for all cancer types, the NSW CLEAR study. Information on past and current MHT use was collected from all participants, along with other lifestyle and demographic factors, using a self-administered questionnaire. Unmatched multivariable logistic regression was performed, adjusting for socio-demographic, reproductive and health behaviour variables, body mass index and breast screening history. Compared to never users of MHT, the adjusted odds ratio (aOR) for breast cancer in current users of any type of MHT was 2.09 (95% CI: 1.57-2.78; p < 0.0001) and for past users of any type of MHT was 1.03 (0.82-1.28; p = 0.8243). For current users of oestrogen-only and oestrogen-progestagen therapy, aORs were 1.80 (1.21-2.68; p = 0.0039) and 2.62 (1.56-4.38; p = 0.0003), respectively. These findings are consistent with those from other international observational studies, that current, but not past, use of MHT is associated with a substantially increased risk of breast cancer.
authors.affiliation: Cancer Research Division, Cancer Council NSW, Woolloomooloo, NSW, Australia.|School of Public Health, Sydney Medical School, University of Sydney, Sydney, NSW, Australia.
authors.forename: Usha
authors.initials: U
authors.lastname: Salagame
authors.affiliation: National Centre for Epidemiology and Population Health, Research School of Population Health, Australian National University, Canberra, ACT, Australia.|Sax Institute, Sydney, NSW, Australia.
authors.forename: Emily
authors.initials: E
authors.lastname: Banks
authors.affiliation: School of Public Health, Sydney Medical School, University of Sydney, Sydney, NSW, Australia.|School of Public Health and Community Medicine, University of New South Wales, Sydney, NSW, Australia.
authors.forename: Freddy
authors.initials: F
authors.lastname: Sitas
authors.affiliation: Cancer Research Division, Cancer Council NSW, Woolloomooloo, NSW, Australia.|School of Public Health, Sydney Medical School, University of Sydney, Sydney, NSW, Australia.|Prince of Wales Clinical School, University of New South Wales, Sydney, NSW, Australia.
authors.forename: Karen
authors.initials: K
authors.lastname: Canfell
mesh_terms: D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology*; D016022:Case-Control Studies; D015914:Estrogen Replacement Therapy / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009517:New South Wales / Q000453:epidemiology; D016017:Odds Ratio; D012307:Risk Factors
keywords: Australia; breast cancer; case-control study; menopausal hormone therapy