Menopausal hormone therapy and breast cancer risk: Impact of different treatments. The European Prospective Investigation into Cancer and Nutrition

Abstract

Menopausal hormone therapy (MHT) is characterized by use of different constituents, regimens and routes of administration. We investigated the association between the use of different types of MHT and breast cancer risk in the EPIC cohort study. The analysis is based on data from 133,744 postmenopausal women. Approximately 133,744 postmenopausal women contributed to this analysis. Information on MHT was derived from country-specific self-administered questionnaires with a single baseline assessment. Incident breast cancers were identified through population cancer registries or by active followup (mean: 8.6 yr). Overall relative risks (RR) and 95% confidence interval (CI) were derived from country-specific Cox proportional hazard models estimates. A total of 4312 primary breast cancers were diagnosed during 1,153,747 person-years of follow-up. Compared with MHT never users, breast cancer risk was higher among current users of estrogen only (RR: 1.42, 95% CI 1.23-1.64) and higher still among current users of combined MHT (RR: 1.77, 95% CI 1.40-2.24; p 5 0.02 for combined vs. estrogen-only). Continuous combined regimens conferred a 43% (95% CI: 19-72%) greater risk compared with

Postmenopausal hormone therapy and the risk of breast cancer in Norway

“…However, previous studies suggest that neither the type of estrogen nor the type of progestin influence the risk of breast cancer. 10,21,28 Thus, differences between the European and U.S. studies may be explained by differences in the monthly doses of progestin.…”

“…39 Our findings of an increased risk of breast cancer for both continuous and sequential combined preparations of EPT are in agreement with previous studies. 3,10,13,15,[19][20][21] A study showed an increased risk of breast cancer for continuous compared with sequential preparations of estradiol-NETA. 27 We found a higher RR in continuous than in sequential preparations, but the differences were not significant.…”

“…17,18 There is less evidence as to whether risk differs between continuous and sequential EPT regimens, 3,10,13,15,[19][20][21] , or whether dose or route of administration matters. 10,21 Further, there is limited documentation on whether type of estrogen or progestin preparation matter, specifically whether EPT combinations containing androgenic progestin are associated with higher risk than other EPTs. In addition, there is limited evidence as to whether estrogen-like compounds, such as tibolone, increase the risk.…”

A Spatial and Temporal Analysis of the Socioeconomic Factors Associated with Breast Cancer in Illinois Using Geographically Weighted Generalized Linear Regression

“…The use of birth control pills in women with higher SES also affects their hormone imbalance and thus may increase the risk of breast cancer (Gierisch et al 2013;Bakken et al 2011). Some other studies have also suggested that because women with higher SES are likely to have less children or have children at later age, their risk of developing breast cancer may be modified (Ewertz et al 1990;Rosner et al 1994).…”

5. Hormonal Effects on the Postmenopausal Breast

“…• Sequential versus continuous MHT. Recent data suggest that sequential MHT is associated with a lesser risk than combined continuous MHT ( 15 ).…”