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Is Hormone Replacement Therapy Safe After Breast Cancer?

The safety of hormone replacement therapy (HRT) after breast cancer treatment still is being debated. In this study, researchers in Seattle identified 174 members of an HMO who used HRT after diagnosis of, and treatment for, breast cancer. These women were compared with 695 women who did not use HRT after breast cancer treatment; controls were matched for age, cancer stage, and several other variables. The median duration of HRT use (determined from the HMO pharmacy database) was 15 months, and median follow-up after initiation of HRT was about 4 years.

In an analysis adjusted for numerous potential confounding factors, the rate of breast cancer recurrence was significantly lower among HRT users than among nonusers (17 vs. 30 per 1000 person-years); HRT users also had significantly lower breast cancer mortality (5 vs. 15 per 1000 person-years) and total mortality (16 vs. 30 per 1000 person-years).

Comment: Surprisingly, in this observational study, disease recurrence and death were less common among women who had been treated for breast cancer previously and who used HRT. However, the duration of HRT use and follow-up were limited. A key question is whether the statistical adjustments for confounders accounted adequately for the possibility that women with better prognoses were more likely to use HRT. While we await the results of randomized trials, the findings of this study can provide some reassurance to women who wish to use HRT after being treated for breast cancer.

— AS Brett

Published in Journal Watch General Medicine June 8, 2001

Citation(s):

O'Meara ES et al. Hormone replacement therapy after a diagnosis of breast cancer in relation to recurrence and mortality. J Natl Cancer Inst 2001 May 16 93 754-762.

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