An expert panel convened by the National Institute of Environmental Health Science's National Toxicology Program has recommended adding steroidal estrogens, such as those used in oral contraceptives and hormone replacement therapy, to the government's list of carcinogens. A number of studies have established that estrogen use is associated with an increased risk of uterine, endometrial, and breast cancers. The agency is soliciting public comment before taking any action.
Although the new classification serves as a precaution, the group did not suggest that estrogen use be restricted or banned, and expressed reservations that the designation might overshadow the hormone's medical value. Physicians and women should weigh the known benefits of steroidal estrogens against their risks, the panel said.
Stephenson J. Estrogen as a Carcinogen. JAMA. 2001;285(3):284. doi:10.1001/jama.285.3.284-JHA00014-4-1