Abstract
Objectives: Reports suggest that combined estrogen plus progestin hormone replacement therapy (HRT) confers a higher breast cancer risk than estrogen alone. We aimed to establish whether breast cancer risk depends on the type of HRT formula. Methods: The cohort consisted of 6586 women, aged 50–64 years, from the Lund area, Sweden, with no reported breast cancer upon inclusion. We obtained information such as HRT use through a questionnaire between December 1995 and February 2000. New breast cancers were identified through the South Swedish tumor registry. Results: Between inclusion and December 2001, 101 women developed breast cancer. Only ever use of the continuous combined estrogen plus progestin (CCEP) formula differed between cases and controls (45.2% versus 23.5%; p = 0.000001). Compared with never users, exclusive CCEP users had the highest age-adjusted hazard ratio HR 3.3 (95% CI: 1.9–5.6; p < 0.001), followed by users of CCEP in addition to other HRT formulas HR 2.8 (95% CI: 1.4–5.5; p = 0.003). No significant increase was seen in women who exclusively used other HRT formulas. Conclusion: Women who used CCEP had over three times the risk of developing breast cancer compared with never users and twice the risk compared with users of other types of HRT.
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Jernström, H., Bendahl, PO., Lidfeldt, J. et al. A prospective study of different types of hormone replacement therapy use and the risk of subsequent breast cancer: the women's health in the Lund area (WHILA) study (Sweden). Cancer Causes Control 14, 673–680 (2003). https://doi.org/10.1023/A:1025635720208
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DOI: https://doi.org/10.1023/A:1025635720208