Panel Advocates Listing Estrogen as ‘Known’ Carcinogen

WASHINGTON—A scientific advisory panel has recommended that steroid estrogens be listed as "known" to cause human cancers. However, the group made no recommendation or suggestion that the commonly used drugs be restricted or eliminated.

The panel, part of the board of scientific counselors to the National Toxicology Program (NTP), specifically noted that estrogens have clear medical benefits, including their use for birth control and as estrogen replacement therapy in postmenopausal women. However, the group also pointed out that use of estrogens increases the risk of uterine, endometrial, and breast cancers.

It voted 8 to 1 that steroid estrogens be listed as "known to be a cause of human cancers" in the next Report on Carcinogens that the NTP sends to Congress. The periodic report is intended to inform the public, the medical community, and regulatory agencies about potential cancer-causing substances. Listing in the report does not automatically invoke any regulatory action.

In making its decision, the panel of outside experts noted that the risks of estrogen use specifically noted in the drug’s labeling are well known in the medical community. It said that women and their physicians need to weigh the known benefits and risks of estrogen in deciding whether to use the agent.

The advisory panel also recommended listing as a "known" human carcinogen ordinary wood dust produced in sanding furniture and cabinets. The panel cited evidence that such dust is associated in industrial settings with increases in cancer of the nasal cavities and sinuses.

It also recommended listing broad-spectrum ultraviolet (UV) radiation in the "known" category. However, for the individual classes of UV—UVA, UVB, and UVC—the advisory group recommended that the NTP list them as "reasonably anticipated to be human carcinogens" because of difficulties in separating out overlapping effects.

Other substances recommended for listing as "reasonably anticipated" to be human carcinogens include:

Chloramphenicol, an antibiotic known to increase the risk of aplastic anemia. Its use is restricted mostly to treating cases of typhoid fever and meningitis when other antibiotics fail.

Methyleugenol, a naturally occurring flavor used in minute quantities to flavor some jellies, baked goods, nonalcoholic beverages, chewing gums, candies, puddings, relishes, and ice creams. It is linked to tumors in laboratory animals, but no studies have as yet associated it with human cancers.

Metallic nickel, used in some medical implants and in the specialty steel and stainless steel industries.

The panel also voted 7 to 3 against recommending that talc be listed as a carcinogen under either category. After reviewing a series of studies of women with ovarian cancer, it decided that suggestions of excess cancers could not be clearly related to the genital use of talc.