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Using Estrogen-Only Hormone Replacement Therapy for 5 Years or More Ups Risk

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Recent news about a dramatic decrease in new breast cancer cases has added to information on how hormone replacement therapy (HRT) might increase breast cancer risk.

But there are different kinds of hormone replacement therapy treatments. Some contain only estrogen, while others contain both estrogen and progesterone (known as combined HRT). Doctors thought that the different types of HRT would affect breast cancer risk differently. Doctors also thought that HRT in pill form might increase risk more than HRT given as a patch (transdermal therapy).

A study found that taking estrogen-only HRT for fewer than five years—as a pill OR a patch—was NOT associated with an increased risk of breast cancer in women living in Finland. When estrogen-only HRT was used for more than five years, breast cancer risk increased slightly.

A strong public health system in Finland makes it relatively easy to study and compare large populations of women over a long period of time. Usually more people in a study and longer follow-up time means more accurate results. In this study, more than 18,000 women who received estrogen-only HRT for at least six months were followed, some for as long as eight years (1994-2002). About 2,200 women in the study were diagnosed with breast cancer. The breast cancer rate of these women were compared to breast cancer rates in women who did not receive HRT.

The concerns about HRT and breast cancer risk are very real. But for some women, the side effects of menopause severely reduce their quality of life. They have to weigh the benefits of HRT against the risks. If you're experiencing severe menopausal side effects and are considering HRT, talk to your doctor about the results of this study. Together, you can decide which type of HRT, if any, might be right for you.

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