After stopping hormone therapy, a woman’s risk of breast cancer drops
A woman’s risk of breast cancer drops “markedly” after she stops taking hormone therapy commonly used to treat menopause, according to a study in this week’s issue of The New England Journal of Medicine.
Three of the study authors are from Seattle’s Fred Hutchinson Cancer Research Center: Ross L. Prentice, Garnet Anderson, and Aaron K. Aragaki.
In 2002, scientists reported the results of a large clinical trial in which healthy postmenopausal women were were randomly assigned to take either Pempro, which contains a combination of estrogen and progestin, or a placebo.
The trial was stopped early after it was determined that the women taking hormones were developing several heart disease, blood clots, breast cancer and other health problems at higher rates than those women taking the placebo.
The research also found that breast cancers tended to be larger and more advanced in those women taking hormones.
The study was conducted by the Women’s Health Initiative.
The news prompted many women to stop taking hormone therapy, and, shortly thereafter, there were reports of a sharp drop in the number of new cases of breast cancers in the U.S. and abroad.
But it was not clear that the drop in hormone use was responsible for the decline.
Some researchers argued that the drop was too fast to be explained to be explained by a change in hormone use.
Others said changes in mammography rates may have caused the detection—but not the true number—of new cases to fall.
In the new study, researchers looked at data from two Women’s Health Initiative studies: the clinical trial reported on in 2002 and another study that followed more than 41,000 women over time tracking various health behaviors including their hormone use.
The analysis of the two studies indicate that the risk of breast cancer associated with taking the hormone therapy did, indeed, go down significantly when the hormones are stopped.
In addition, the study found that the longer a woman takes hormone therapy the higher her risk of developing breast cancer, with the risk doubling after five years.
The drop in new cases did not seem be due to changes in mammography rates, the researchers found.
“The increased risk of breast cancer associated with the use of estrogen plus progestin declined markedly soon after discontinuation of combine hormone therapy and was unrelated to changes in frequency of mammography,” the researchers conclude.
Category: Breast Cancer, Drugs & Medicines, Fred Hutchinson Cancer Research Center, Women's Health
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