Estradiol concentration in breast tissue obtained during surgery in women taking oral contraceptives or adjuvant endocrine therapy

Abstract

Background: Several studies report a breast cancer (BC) incidence decrease subsequent to the decrease in Hormone replacement therapy (HRT) use. But itsmagnitude and the time-lag may vary between countries. This may reflect differences in populations, previous type and prevalence of HRT use and BC screening. Aim: To review systematically studies assessing the relation between BC incidence and change of HRT use. Material andmethod:Descriptive analysis of themethodology of the studies including design limitations and presence of confounding factors, data sources for BC and HRT and regimens of HRT used. Results and discussion: Eighteen articles were selected. Most studies were ecological and confounding factors such asmammography screening and changes in reproductive and life style habits could not be excluded. Sources of data on BC and HRTwere heterogeneous and only few data on HRT regimens used were available. Most studies concluded that the decrease in HRT use during the last decade was probably associated with a BC incidence decrease, especially for women aged 50 or more. Conclusions: Data, mostly from epidemiological studies, suggest that the BC incidence decrease can be partly attributed to the HRT use drop. Nevertheless, available studies are hampered by a number of limitations and it remains difficult to evaluate the exact impact of HRT drop on BC incidence decrease. Especially, the studies are seldom based on detailed individual data and do not provide information onused regimens, type of cancers andpossible confounding factors.