An expert advisory panel today recommended to the federal government that steroidal estrogens be listed as a "known" cause of cancer in humans in a future Report on Carcinogens. 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 panel agreed 8 to 1 that these hormones cause an elevated risk and should be considered not merely as associated with increased cancer but as substances that are "known to be a cause of human cancers."
The federal Report on Carcinogens is required by Congress to inform the public, medical community and regulatory agencies about potential cancer-causing substances. It is prepared by the National Toxicology Program, which is headquartered at the National Institute of Environmental Health Sciences in Research Triangle Park, NC. NIEHS/NTP sought the views of the panel of scientists as one step in the development of the Tenth Report on Carcinogens, which will be written and published after further public comment and review.
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.
Another medical product, the antibiotic chloramphenicol, was recommended for listing as "reasonably anticipated" to be a cause of human cancer based on evidence of an association with childhood leukemia. 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
Contact: Bill Grigg 301-492-3378
NIH/National Institute of Environmental Health Sciences