Continuous combined hormone replacement therapy and risk of endometrial cancer

OBJECTIVE: Postmenopausal women who receive sequential hormone replacement therapy with estrogen Combined with progestogen for 10 to 24 dime for a pro longed period may have an elevated endometrial cancer risk relative to thos e who have never received hormone replacement therapy. We investigated whet her daily use of estrogen and progestogen (continuous combined hormone repl acement therapy) could diminish any excess endometrial cancer risk. STUDY DESIGN: A population-based study in Washington State obtained intervi ew data from 969 women aged 45 to 74 years with endometrial cancer diagnose d during 1985 through 1991 or 1994 through 1995 and from 1325 age-matched c ontrol subjects selected primarily by random digit dialing. Women who had r eceived only continuous combined hormone replacement therapy were compared with women who had only received another hormone replacement therapy regime n or who had never received hormone replacement-therapy RESULTS: The risk of endometrial cancer among users of continuous combined hormone replacement therapy (n = 9 case patients, n = 33 control subjects) relative to women who had never received hormone replacement therapy was 0. 6 (95% confidence interval, 0.3-1.3); the risk relative to women who receiv ed hormone replacement that included progestogen for 10 to 24 dime was 0.4 (95% confidence interval, 0.2-1.1). Most Continuous combined hormone replac ement therapy use was short-term (<72 months) or recent tin the previous; 2 4 months). CONCLUSION: Women who had received continuous combined hormone replacement therapy for several years did not appear to be at any increased risk for en dometrial cancer relative to women who had never received hormone replaceme nt therapy and may in fact be at decreased risk for endometrial cancer.