HRT May Not Be As Risky

A new study just published in the Journal of the National Cancer Institute reports that hormone replacement therapy (HRT) given to women diagnosed with invasive breast cancer may actually be associated with a lower risk of breast cancer recurrence, breast cancer mortality, and overall mortality.

Researchers have long been concerned that the estrogens used in HRT could theoretically stimulate recurrence in women whose breast cancer is estrogen-receptor positive. (Their cancer may be stimulated by the presence of hormones such as estrogen.) Therefore, physicians have often cautioned these women to avoid HRT, which can otherwise have positive benefits in terms of a significantly reduced risk of heart disease and osteoporosis.

However, Ellen O'Meara, Ph.D., of the University of Washington, Seattle, and colleagues found that HRT users had about half the risk of breast cancer recurrence as nonusers of HRT. In addition, they had about one-third the risk of death from breast cancer and just under half the risk of death from any cause.

The study involved women enrolled in the Group Health Cooperative of Puget Sound. Women who were diagnosed with breast cancer from 1977 through 1994 were identified by searching the state's Cancer Surveillance System. Group Health pharmacy records were then searched for women who took HRT after their diagnosis of breast cancer.

Each of the 174 HRT users was then matched to four randomly selected nonusers of HRT with similar age, disease stage, and year of diagnosis. Women in the analysis ranged in age from 35 to 74 years and were recurrence-free when they began hormone replacement therapy. The women were then followed for a median of 3.7 years for recurrence and 4.6 years for mortality.

The researchers cautioned that the sample size was small and that their results should therefore be considered preliminary. It was also not clear that the HRT itself was solely responsible for the lower incidence rates. Furthermore, they reported that the risk of breast cancer developing in the other breast was actually higher among women who used HRT after their initial diagnosis. This latter result, the authors warned, reinforces the need for caution in assessing the overall impact of HRT use after breast cancer.

In an accompanying editorial, Jack Cuzick, Ph.D. of the Imperial Cancer Research Fund in London also cautioned that the follow-up period of O'Meara's study was relatively short. Nonetheless, he said, the study gives added support and urgency to a number of ongoing clinical trials of HRT in symptomatic women with breast cancer.

SOURCE:
Journal of the National Cancer Institute, May 16, 2001; 93:754-762

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