Human carcinogenic risk evaluation, Part III: Assessing cancer hazard and risk in human drug development

Assessing cancer risk for human pharmaceuticals is important because drugs are taken at pharmacologically active doses and often on a chronic basis. Epidemiologic studies on patient populations have limited value because of the long latency period for most cancers and because these studies lack sensitivity. The Center for Drug Evaluation and Research (CDER) of the U.S. Food and Drug Administration relies on short-term surrogate assays (genetic toxicology studies) to assess risk to patients involved in clinical trials and on rodent carcinogenicity studies to assess cancer risk for drug approval. Unlike some other agencies that typically perform quantitative risk assessments on chemical pollutants or pesticide products, CDER does not perform such quantitative extrapolations. Rather, the evaluation of risk is the result of an integrated assessment of what is known about the drug, and risk is considered in the context of the clinical benefit. Mode of action of carcinogenesis and thresholds for effects are important considerations. The results of carcinogenicity studies of approved products are published in the drug labeling and individual clinicians balance risk and benefit in making prescribing decisions.