While panel members said these steroids have important medical uses and clear medical benefits, they have long been associated under certain conditions of use with a risk of uterine and breast cancers. The federal Report on Carcinogens is required by Congress to inform the public, medical community and regulatory agencies about potential cancer-causing substances.
Estrogens occur naturally in women and to a lesser degree in men.
They have important medical uses in hormone replacement therapies in post-menopausal women and for birth control. Their use has long been associated with a risk of uterine, endometrial and breast cancers. They are so labeled, panelists said, and doctors and women should weigh their known benefits against these risks. There was no suggestion by the panelists that medical use of estrogen be restricted or eliminated. Found to be effective against typhus in 1948, it was one of the first antibiotics in large-scale production but after being linked to a risk of potentially fatal aplastic anemia, the drug's use was limited to cases of typhoid fever and meningitis when other antibiotics were ineffective.