Impact of postmenopausal hormone therapy on cardiovascular events and cancer: Pooled data from clinical trials

Objective: To examine the incidence of cardiovascular diseases and cancer from published clinical trials that studied other outcomes of postmenopausal hormone therapy as some surveys have suggested that it may decrease the incidence of cardiovascular diseases and increase the incidence of hormone dependent cancers. Design: Trials that compared hormone therapy with placebo, no therapy, or vitamins and minerals in comparable groups of postmenopausal women and reported cardiovascular or cancer outcomes were searched from the literature. Subjects: 22 trials with 4124 women were identified. In each group, the numbers of women with cardiovascular and cancer events were summed and divided by the numbers of women originally allocated to the groups. Results: Data on cardiovascular events and cancer were usually given incidentally, either as a reason for dropping out of a study or in a list of adverse effects. The calculated odds ratios for women taking hormones versus those not taking hormones was 1.39 (95% confidence interval 0.48 to 3.95) for cardiovascular events without pulmonary embolus and deep vein thrombosis and 1.64 (0.65 to 4.18) with them. It is unlikely that such results would have occurred if the true odds ratio were 0.7 or less. For cancers, the numbers of reported events were too low for a useful conclusion. Conclusions: The results of these pooled data do not support the notion that postmenopausal hormone therapy prevents cardiovascular events.