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Article first published online: 30 AUG 2012
Copyright © 2012 UICC
International Journal of Cancer
Volume 132, Issue 2, pages 417–426, 15 January 2013
How to Cite
Trabert, B., Wentzensen, N., Yang, H. P., Sherman, M. E., Hollenbeck, A. R., Park, Y. and Brinton, L. A. (2013), Is estrogen plus progestin menopausal hormone therapy safe with respect to endometrial cancer risk? . Int. J. Cancer, 132: 417–426. doi: 10.1002/ijc.27623
This article is dedicated in the memory of Dr. Arthur Schatzkin, visionary investigator who founded the NIH-AARP Diet and Health Study.
Published 2012. This article is a US Government work and, as such, is in the public domain of the United States of America.
- Issue published online: 20 NOV 2012
- Article first published online: 30 AUG 2012
- Accepted manuscript online: 3 MAY 2012 06:07AM EST
- Manuscript Accepted: 23 APR 2012
- Manuscript Received: 28 FEB 2012
- Intramural Research Program of the National Cancer Institute
- National Institutes of Health
- Department of Health and Human Services
- endometrial cancer;
- estrogen plus progestin;
- body mass index;
- menopausal hormone therapy
Given the strong link between use of unopposed estrogens and development of endometrial cancers, estrogens are usually prescribed with a progestin, particularly for women with intact uteri. Some studies suggest that sequential use of progestins may increase risk; however, the moderating effects of usage patterns or patient characteristics, including body mass index (BMI), are unknown. We evaluated menopausal hormone use and incident endometrial cancer (n = 885) in 68,419 postmenopausal women with intact uteri enrolled in the National Institutes of Health-American Association of Retired Persons Diet and Health study. Participants completed a risk factor questionnaire in 1996–1997 and were followed up through 2006. Hazard rate ratios (RRs) and 95% confidence intervals (CIs) were estimated using Cox regression. Among 19,131 women reporting exclusive estrogen plus progestin use, 176 developed endometrial cancer (RR = 0.88; 95% CI = 0.74–1.06). Long-duration (≥10 years) sequential (<15 days progestin per month) estrogen plus progestin use was positively associated with risk (RR = 1.88; 95% CI = 1.36–2.60], whereas continuous (>25 days progestin per month) estrogen plus progestin use was associated with a decreased risk (RR = 0.64; 95% CI = 0.49–0.83). Increased risk for sequential estrogen plus progestin was seen only among thin-to-normal weight women (BMI < 25 kg/m2; RR = 2.53). Our findings support that specific categories of estrogen plus progestin use increases endometrial cancer risk, specifically long durations of sequential progestins, whereas decreased endometrial cancer risk was observed for users of short-duration continuous progestins. Risks were highest among thin-to-normal weight women, presumably reflecting their lower endogenous estrogen levels, suggesting that menopausal hormones and obesity increase endometrial cancer through common etiologic pathways.