Self-selection for mammography screening according to use of hormone replacement therapy: A systematic literature review.

Mammography screening participation may be influenced by the awareness of an increase in breast cancer risk due to hormone replacement therapy (HRT), which received particular attention upon publication of the Women's Health Initiative (WHI) trial results in 2002. Our aim was to synthesize evidence on a potential self-selection for mammography screening according to HRT use. We systematically searched the literature (MEDLINE, EMBASE, CINAHL) for studies reporting on the association between HRT use and mammography screening participation. Data were extracted independently by two reviewers. Overall, 2018 studies were identified. Of these, 32 studies from nine countries, predominantly from North America (50%) and Europe (28%), were included. In studies from all countries and 94% of all studies, higher mammography screening uptake among HRT users compared to non-users was reported. In all 21 studies reporting an odds ratio, the association was positive, and in about 70% of these studies, this association was ≥2. This also held true for studies exclusively using data collected before publication of the WHI findings in 2002 (63% of all studies). The association was not restricted to certain types of screening (organized vs. opportunistic) or certain types of HRT (combined vs. estrogen-only). We found a consistent and relevant association between mammography screening uptake and HRT use. This is of considerable relevance for the design and interpretation of studies investigating risk factors or evaluating preventive measures for breast cancer.