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

BMJ 1997; 315 doi: (Published 19 July 1997) Cite this as: BMJ 1997;315:149
  1. Elina Hemminki, research professora,
  2. Klim McPherson, professor of public health epidemiologyb
  1. a National Research and Development Centre for Welfare and Health, Health Services Research Unit, PO Box 220, 00531 Helsinki, Finland
  2. b London School of Hygiene and Tropical Medicine, Health Promotion Unit (Department of Public Health and Policy), London WC1E 7HT
  1. Correspondence to: Professor Hemminki
  • Accepted 15 April 1997


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.

Key messages

  • The results of these pooled data do not support the notion that postmenopausal hormone therapy prevents cardiovascular events

  • These results concern only short term effects of postmenopausal hormone therapy, and long term effects may be different

  • There have been hundreds of trials studying the impact of hormones on various physiological phenomena, laboratory values, osteoporosis, symptoms, or various health problems but few fully report adverse effects. Small trials would be useful in studying unintended effects if they were more systematically reported


    • Accepted 15 April 1997
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