March 14, 1980

Carcinogenicity Testing of Drugs

Author Affiliations

National Toxicology Program Research Triangle Park, NC

JAMA. 1980;243(10):1035. doi:10.1001/jama.1980.03300360011005

To the Editor.—  I agree with John C. Ballin, MD (242:26, 1979), that the results of studies in which large doses are given to animals for a lifetime do not necessarily mean that "such drugs or chemicals are carcinogenic in man when taken according to label directions." But the studies do not necessarily mean that such drugs or chemicals are not carcinogenic when given in therapeutic doses.The purpose of the studies at the National Cancer Institute (as part of the National Toxicology Program) is to detect chemicals that are capable of producing cancer. To this end we use the maximum dose of the test chemical, a dose that does not interfere with normal growth and function. If no cancers are produced, we can feel comfortable that the substance is not likely to be carcinogenic. If cancers are produced, we must assume that some qualitative risk exists for humans. Unfortunately,