HHS adds tamoxifen to carcinogen report

The Department of Health and Human Services added the cancer-fighting drug tamoxifen to the ninth edition of its report on carcinogens. The report, which is prepared every two years by the National Toxicology Program at the National Institute of Environmental Health Sciences, Washington, identifies substances, such as metals, pesticides, drugs and natural and synthetic chemicals, and mixtures and exposure circumstances that are known or are reasonably anticipated to cause cancer and to which a significant number of Americans are exposed.

Tamoxifen, the active ingredient in AstraZeneca's Nolvadex,® was approved by the U.S. Food and Drug Administration for treatment of breast cancer, for reducing the recurrence of breast cancer in women with a previous diagnosis of breast cancer and for decreasing breast cancer in women who have a high risk of getting breast cancer. According to the report, "Tamoxifen is listed in the ninth report as a 'known human carcinogen' based on evidence from studies in humans that indicate that tamoxifen increases the risk of uterine cancer in women."

Experts express concern

The addition of tamoxifen to the report has caused some concern among some cancer organizations that women taking the drug may discontinue its use. "It would be unfortunate if [the report] would frighten women away from considering [tamoxifen] use particularly as an adjuvant therapy since it's responsible for so much of the decline in mortality for breast cancer," said Joann Schellenbach, national director of media relations for the Atlanta-based American Cancer Society. "There's obviously a risk of uterine cancer, but compared to the risk of a recurrence of breast cancer, it's small."

The report does, however, acknowledge the benefits of tamoxifen for breast cancer patients. "There has been concern expressed that the listing of tamoxifen on the ninth report could raise concerns among patients regarding its use for cancer treatment or prevention," read a release from the National Institutes of Health. "It is, therefore, important to again note that these listings do not address potential benefits of exposures to certain carcinogenic substances. In this instance, the benefits of exposure to the substance have been determined by the Food and Drug Administration to outweigh the risks entailed."

Schellenbach said it was too early to tell what effect the addition of tamoxifen to the carcinogens list would have on patients taking the drug. She encouraged women who are taking tamoxifen and are concerned about the risks to consult their doctors before discontinuing its use. PR