Seattle ? When reports linked a remarkable decline in nationwide breast-cancer cases to falling numbers of women taking menopausal hormones, skeptics said it could just be that it was actually a drop in mammograms that meant fewer cancers were being detected.

Not so, says a large national study released Tuesday.

Researchers from Seattle and three other locations around the country say that their study of breast cancer rates among more than 200,000 women – all of whom received regular mammograms – showed cancer rates fell significantly after American women began abandoning menopausal hormone therapy about seven years ago. The findings are to be published in today’s Journal of the National Cancer Institute.

The study is the first to include only women who were regularly screened with mammography, thus reducing the possibility that a drop in cancer rates could be the result of fewer screenings. It also adds to a growing body of evidence against hormone therapy.

“If you take away the hormones, your risk of breast cancer goes down,” said Dr. Karla Kerlikowske, a physician at the San Francisco VA Medical Center and lead author of the study.

The study found a decrease in breast-cancer cases that coincided with the decline in women taking hormone pills to treat menopausal symptoms such as hot flashes, vaginal dryness and night sweats.