Hormones Do Not Worsen Breast Cancer Prognosis, Study Shows

From the WebMD Archives

Feb. 4, 2000 (Los Angeles) -- Breast tumors in women using hormone-replacement therapy (HRT) do not differ in severity from those in women who did not use HRT and have a similar projected outcome, researchers in Scotland have found. Their study appears in the current issue of the British Medical Journal.

These findings come on the heels of two recent studies showing that HRT may interfere with mammography results, and that combination HRT may increase a woman's risk of breast cancer. The fact that the prognosis is no worse in women who were using HRT "is reassuring to doctors prescribing hormone-replacement therapy," the authors write.

"It is gratifying to know that this study did not show increased aggressiveness in terms of tumor size and type in women who are on estrogen," says Glen R. Justice, MD, medical director of the Orange County Regional Cancer Center at the Fountain Valley Regional Medical Center in Fountain Valley, Calif. Some investigators have even suggested that HRT might make breast tumors more responsive to therapy, but Justice tells WebMD, "I never did assume that people on hormones had a better prognosis, and I'm glad this study debunks that myth."

To conduct their study, lead author Sheila Stallard and her colleagues at the North Glasgow Hospitals University NHS Trust studied over 1,100 women who were diagnosed with breast cancer between May 1988 and December 1993. A total of 166 (14.9%) of the women were using HRT at the time they developed breast cancer. When the authors analyzed each case for tumor type, grade, and size, they found no difference between women who were taking HRT at the time of diagnosis and those who were not.

"These findings are consistent with our general thinking of the way estrogen is believed to act on breast tissue," says Anne Blackwood, MD, assistant professor of medicine and epidemiology at the University of Pennsylvania. She tells WebMD that in the U.S., women are more likely to be screened for breast cancer when they receive HRT, which may promote earlier diagnosis and a better long-term outcome. But "there are no long-term follow-up data and no information on survival in this study, so we don't know the impact on the prognostic factors of women who go off HRT and are treated for their breast cancer." Neither she nor Justice was involved in the study.

HRT is still a valuable therapy, Justice tells WebMD. It can lengthen life by as much as one year through a decrease in the risk of heart disease and fractures from osteoporosis. However, women with a family history of breast cancer or a biopsy showing any abnormalities should not take HRT and are probably good candidates for the drug tamoxifen, which can decrease the risk of breast cancer by 50% in high-risk women. According to Blackwood, "The key issue is for each woman to have a clear discussion with her doctor, who will have a better idea of her risk of breast cancer. For the average woman with no breast-cancer risk factors, HRT remains a safe and viable option."

Vital Information:

  • Researchers analyzed a group of patients diagnosed with breast cancer and found that those taking HRT had a similar tumor characteristics and prognoses to those not taking the therapy.
  • HRT can decrease the risks of heart disease and osteoporosis, but may increase the risk of breast cancer.
  • Women should discuss their individual risk profiles with their doctor when deciding whether or not to take HRT or an alternative, such as tamoxifen.