Epidemiological studies of anticancer drug carcinogenicity.

In recent years, epidemiological methods have been used increasingly to study the carcinogenicity of drugs used in the chemotherapy of cancer. Such studies are useful to clinicians in identifying therapeutic agents with particular long-term risk to patients. They can also provide information on the dose- and time-related risks of cancer in one of the few human populations intentionally exposed to known levels of carcinogens. Aspects of epidemiological studies of second cancer risk are described, including sources of cases, study design, statistical methods, and possible biases. Results from a cohort study of second cancers following ovarian cancer, testicular cancer and Hodgkin's disease and from a case-control study of leukaemia following Hodgkin's disease are also given.