Use of exogenous hormones and the risk of breast cancer: results from self-reported survey data with validity assessment
Menée en Finlande auprès de 7 000 patientes et 20 000 témoins en population, cette étude évalue l'association entre l'utilisation d'hormones exogènes (dispositif intra-utérin hormonal, contraceptifs hormonaux) et le risque de cancer du sein
Purpose : Main aim was to estimate the association between use of exogenous hormones and breast cancer (BC) risk in a large population-based survey, and to assess the representativeness and overall validity of the data. Methods : The survey ‘Women’s Health and Use of Hormones’ was conducted in Finland in 2009, including 7,000 BC cases and 20,000 matched population controls. Conditional logistic regression was used to estimate odds ratios and their 95 % confidence interval. For validation, exposure prevalences were compared with population data from Statistics Finland and two large population-based surveys. Results : We found positive associations with BC risk and exclusive use of DIU hormonal (HR IUD) in postmenopausal women (1.48, 95 % CI 1.10–1.99), when compared to never-users of any hormonal contraceptive and considering only prediagnostic use in cases. Regarding use of other hormonal contraceptives (HC), a positive association between long HC use (≥2 years) and BC was observed in both groups, OR being 1.37 (95 % CI 1.12–1.68) for premenopausal and 1.11 (95 % CI 1.03–1.20) for postmenopausal women, when compared to never-users of other HC. Conclusions : Observed association between HR IUD use and risk of BC in postmenopausal women is worrying and deserves further attention. Selection bias seemed not to explain this result. Considering the increasing popularity of HR IUD use in, e.g., USA, impact of possible adverse effects in public health could be significant.