Combination Hormone Use Linked to Increased Risk of Estrogen Receptor–Positive Breast Cancer in Postmenopausal African American Women
In a study reported in the Journal of the National Cancer Institute, Rosenberg et al found that use of estrogen with progestin is associated with an increased risk of estrogen receptor–positive breast cancer in postmenopausal African American women.
Study Details
The study involved data on 1,132 case patients with estrogen receptor–positive disease, 512 case patients with estrogen receptor–negative disease, and 6,693 control patients from the AMBER consortium enrolled between 1993 and 2013. Overall, 48% of the control patients had used estrogen alone (28%), combination hormone therapy (13%), or both (6%).
Increased Risk of Breast Cancer
The risk of estrogen receptor–positive breast cancer was significantly increased with the use of combination hormone therapy vs never use of estrogen alone or combination therapy (odds ratio [OR] = 1.50, 95% confidence interval [CI] = 1.25–1.79). Increases in risk were observed with long-term use (OR = 1.75, 95% CI = 1.13–2.73, for duration ≥ 10 years), recent use (OR = 1.55, 95% CI = 1.21–1.99, for use within the past 5 years), among nonobese women (OR = 1.91, 95% CI = 1.29–2.83), and among women with an interval between the onset of menopause and the initiation of combination use of < 5 years (OR = 1.43, 95% CI = 1.11–1.85) or ≥ 5 years (OR = 1.78, 95% CI = 1.34–2.37).
There was no significant association between combination hormone use and risk of estrogen receptor–negative breast cancer or between use of estrogen alone and the risk of either estrogen receptor–positive or estrogen receptor–negative breast cancer.
The investigators concluded: “Use of estrogen with progestin increases risk of ER (-positive) breast cancer in African American women. A decrease in use would be expected to reduce the number of ER (-positive) cancers.”
The study was funded by the National Institutes of Health, the Breast Cancer Research Foundation, and the University Cancer Research Fund of North Carolina.
Lynn Rosenberg, ScD, of Slone Epidemiology Center, Boston University, is the corresponding author of the Journal of the National Cancer Institute article.
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