Although the medical and drug industries continue to recommend artificial estrogen replacement for women, a government scientific advisory panel recommended that the chemical be added to the nation's list of cancer-causing agents.

Members of the National Toxicology Program advisory committee voted 8-1 to list the drug as a carcinogen on December 15, 2000.

An estimated 16 million postmenopausal women have received prescriptions for hormone therapy, despite studies which show that estrogen is associated with an increase in endometrial cancer and breast cancer.

However, the vast majority of the women receiving the treatment have never been warned about the potentially serious side effects.

Testifying before the committee, Michelle Medinsky, a toxicologist from Durham, N.C., noted, "Physicians never discuss any of these risks when they are prescribing hormone therapy. They only discuss benefits."

When estrogen's potential for causing cancer was discovered, progestin was added to the estrogen in most hormone replacement therapy regimens, in order to reduce the cancer risk. However, a recent research study found that the combination increased the woman's risk of breast cancer.