Continuous Combined Estrogen Plus Progestin and Endometrial Cancer: The Women's Health Initiative Randomized Trial. 

 -  2016 
<br/><br/>Available online from MWHC library: 1996 - present (after 1 year), Available in print through MWHC library: 1999 - 2006 
<br/><br/> BACKGROUND: While progestin addition to estrogen mitigates endometrial cancer risk, the magnitude of the effect on incidence, specific endometrial cancer histologies, and endometrial cancer mortality remains unsettled. These issues were assessed by analyses after extended follow-up of the Women's Health Initiative (WHI) randomized clinical trial evaluating continuous combined estrogen plus progestin use.  CONCLUSION: In postmenopausal women, continuous combined estrogen plus progestin decreases endometrial cancer incidence.Copyright © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.  METHODS: The WHI enrolled 16 608 postmenopausal women into a randomly assigned, double-blind, placebo-controlled trial. Women age 50 to 79 years with intact uteri with normal endometrial biopsy at entry were randomly assigned to once-daily 0.625 mg conjugated equine estrogen plus 2.5mg medroxyprogesterone acetate (n = 8506) as a single pill or matching placebo (n = 8102). Follow-up beyond the original trial completion date required reconsent, obtained from 12 788 (83%) of surviving participants. Analyses were by intent-to-treat. All statistical tests were two-sided.  RESULTS: After 5.6 years' median intervention and 13 years' median cumulative follow-up, there were fewer endometrial cancers in the combined hormone therapy compared with the placebo group (66 vs 95 case patients, yearly incidence, 0.06% vs 0.10%; hazard ratio [HR] = 0.65, 95% confidence interval [CI] = 0.48 to 0.89, P = .007). While there were somewhat fewer endometrial cancers during intervention (25 vs 30, respectively; HR = 0.77, 95% CI = 0.45 to 1.31), the difference became statistically significant postintervention (41 vs 65, respectively; HR = 0.59, 95% CI = 0.40 to 0.88, P = .008), but hazard ratios did not differ between phases (P difference = .46). There was a statistically nonsignificant reduction in deaths from endometrial cancer in the estrogen plus progestin group (5 vs 11 deaths, HR = 0.42, 95% CI = 0.15 to 1.22). 
<br/><br/><br/>English 
<br/><br/><label>ISSN: </label>0027-8874 
<br/><br/><label>Subjects--Topical Terms: </label><br/>*Endometrial Neoplasms/ci [Chemically Induced]<br/>*Endometrial Neoplasms/ep [Epidemiology]<br/>*Estrogen Replacement Therapy<br/>*Estrogens, Conjugated (USP)/ad [Administration & Dosage]<br/>*Estrogens, Conjugated (USP)/ae [Adverse Effects]<br/>*Medroxyprogesterone Acetate/ad [Administration & Dosage]<br/>*Medroxyprogesterone Acetate/ae [Adverse Effects]<br/>Aged<br/>Double-Blind Method<br/>Drug Administration Schedule<br/>Endometrial Neoplasms/mo [Mortality]<br/>Endometrial Neoplasms/su [Surgery]<br/>Estrogen Replacement Therapy/ae [Adverse Effects]<br/>Estrogen Replacement Therapy/mt [Methods]<br/>Female<br/>Humans<br/>Hysterectomy<br/>Incidence<br/>Kaplan-Meier Estimate<br/>Middle Aged<br/>Odds Ratio<br/>Postmenopause<br/>United States/ep [Epidemiology]<br/>Women's Health
<br/><br/><label>Subjects--Geographic Terms: </label><br/>MedStar Health Research Institute
<br/><br/><label>Index Terms--Function: </label><br/>Journal Article<br/>Randomized Controlled Trial<br/>Research Support, N.I.H., Extramural