For women going through menopause, the decision whether to take hormone replacement therapy has been controversial and confusing. Just last year 40 million prescriptions for hormones were filled in the United States.
CBS News medical correspondent Dr. Jon LaPook reports a new study adds to the evidence that taking hormone replacement therapy after menopause can be dangerous.
"What's important about this study is that it really provides tremendous clarity regarding the risks of hormone replacement therapy," says Dr. Freya Schnabel, of New York University's Langone Medical Center.
In 2002, a large study of postmenopausal women found that the combination of estrogen and progesterone led to an increase in cases of breast cancer -- about one extra case for every 1,000 women taking hormones for a year.
Following the report, the number of women using hormones fell by about half and breast cancer rates declined.
Researchers continued to study the women for an average of 11 years and found there was not only an increase in the number of breast cancer cases, but the cancers were more likely to be advanced and cause death. The increase was slight: a little over one extra death per year for every 10,000 women.
"I think from this point onward any woman who's considering taking hormone replacement therapy will need to genuinely consider these risks," says Schnabel.
In this study women were on average 63 years old and taking a larger dose of hormones that is commonly prescribed today.
This study not only shows an increase in the incidence of breast cancer but an increase in deaths. Even though that increase is slight there are so many people taking hormone replacement therapy that it really has to be taken into consideration.
Most women in this study were older than the typical age of the person taking hormone replacement for menopausal symptoms, 63. Most menopausal women are around 50.
At the higher dose used then as opposed to the lower dose used now, is there the same effect? At the end of the day, people will have to talk with their doctors and assess the risk.