Research of two new statistic based study of Women's Health Initiative data have convincingly pointed out that the recent and sudden decline in breast cancer incidence in the United States is because of a dramatic drop in the usage of estrogen-plus-progestin menopausal hormone therapy. It is not due to the less usage of mammography as earlier believed by skeptics.

The San Antonio Breast Cancer Symposium said that the message that one gets from this analyses is that the breast cancer risk caused by hormone therapy increases faster and more sharply than recognized earlier and it also quickly declines after the HT is stopped.

A medical oncologist at the Los Angeles Biomedical Research Institute in Torrance, California said, "The good news for women here is that the risk rapidly dissipated in just a year or year and a half."

Critics say that the steep reduction in the number of breast cancer cases might be aan artifact which resulted from women who underwent lesser of mammograms after they stopped communicating with HT.