Cardiovascular and cancer morbidity and mortality and sudden cardiac deathin postmenopausal women on oestrogen replacement therapy (ERT)

Background Advantages and disadvantages of postmenopausal oestrogen replace ment therapy (ERT) are still not clear. We aimed to analyse the relation be tween postmenopausal oestrogen replacement therapy (ERT), cardiovascular di sease, and cancer. Methods We examined 7944 women born between 1923 and 1930, who participated in a mammography screening for breast cancer, and who were followed up fro m 1987 to 1995, The follow-up consisted of 53 305 person-years. 988 women w ere current users and 757 were former users of ERT. Information about hormo ne use and health events was obtained through biennial questionnaires and r ecording and linking information from the hospital discharge registers of t he region, the national cancer register, the social insurance reimbursement register, and the national death register. We used proportional-hazards mo dels to calculate risk ratios and 95% CIs, adjusted for eight confounding v ariables. Findings Current ERT was associated with decreased cardiovascular mortality and a decrease in sudden cardiac death. Adjusted risk ratio (RR) for cardi ovascular mortality in current users was 0.21 (95% CI 0.08-0.59) and in for mer users 0.75 (0.41-1.37). Absolute risk per 1000 person-years for deaths from acute myocardial infarction (AMI) was 1.1 in never users, 1.2 in forme r users, and 0.45 in current users (p=0.197). Corresponding absolute risk f or other coronary-artery-disease (CAD) deaths was 1.0, 0.81, and 0 (p=0.009 ), and for deaths from stroke 1.2, 1.0, and 0.15 (p=0.012), Absolute risk f or sudden cardiac death was 1.6 in never users, 1.0 in former users, and 0 in current users (p<0.001). Cardiovascular morbidity was not decreased by E RT: the RR for current use was 1.07 (0.86-1.32) and for former use 1.11 (0. 89-1.39). Incidence of cardiovascular disease per 1000 person-years was 24. 9 in never users, 23.4 in former users, and 20.9 in current users (p=0.153) . Breast-cancer morbidity did not increase with current ERT--the RR was 0.5 7 (0.27-1.20). Incidence of breast cancer was 1.8, 1.6, and 1.0 in never, f ormer, and current users (p=0.242). Endometrial cancer increased with curre nt ERT-the RR was 5.06 (2.47-10.41). Incidence of endometrial cancer was 0. 52 in never users, 0.51 in former users, and 2.1 in current users (p<0.001) . Interpretation Current ERT reduced primarily sudden cardiac death and predi cted reduced cardiovascular mortality, but did not reduce morbidity. ERT di d not increase the risk of breast cancer, but associated with increased ris k of endometrial cancer.