Estrogen plus progestin menopausal hormone use: a safe regimen of use with respect to endometrial cancer risk?

Tuesday, October 25, 2011 — Poster Session II
Noon – 2:00 p.m.	Natcher Conference Center	NCI	EPID-14

* FARE Award Winner

Authors

• B Trabert
• N Wentzensen
• HP Yang
• ME Sherman
• A Hollenbeck
• Y Park
• LA Brinton

Abstract

Given a strong link between unopposed estrogens and development of endometrial cancers, estrogens are usually prescribed with progestin (E+P), particularly for women with intact uteri. Studies suggest that sequential use of progestins may increase risk; however, associations with usage patterns and body mass index (BMI) remain unclear. We evaluated menopausal hormone use and incident endometrial cancer (n=885) in 68,479 postmenopausal women with intact uteri enrolled in the NIH-AARP Diet and Health Study. Relative risks (RR) and 95% confidence intervals (CI) were estimated using Cox regression. Among 19,131 women reporting exclusive E+P use, 176 developed endometrial cancer [RR=0.88; 95%CI=0.74-1.06]. Long-duration E+P was positively associated with risk [RR=1.37; 95%CI=1.07-1.75], and this was largely driven by higher risks for sequential (<15 days/month) progestins. Significant increased risks for E+P use were seen only among normal weight women (BMI<25 kg/m^2) [RR=1.78], with the highest risks for long-duration [2.92] or sequential regimen [2.53] usage. Our findings support that E+P may not be totally safe with respect to endometrial cancer risk, particularly when long-durations of sequential progestins are involved. That normal weight women, with lower endogenous estrogen, were those most affected by E+P use, supports that menopausal hormones and obesity increase endometrial cancer through common etiologic pathways.

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