DESCRIPTION: The application is to continue the CCS to assess the effects of medications and other factors on the risk of cancer. Multiple case-control studies are conducted within a single collection system. Nurse-interviewers, stationed at participating hospitals administer standard questionnaires to patients admitted for recently diagnosed cancers and other illnesses, to obtain histories of both prescription and nonprescription medication use and information on potential confounders or modifiers of exposure-disease associations. The usefulness of CCS for quantifying associations with cancer risk, documenting safety in the absence of effect, and discovering unexpected associations has been extensively documented. Adverse effects (e.g. estrogens and endometrial cancer), protective effects (e.g. oral contraceptives and ovarian cancer), and safety (benzodiazepines and 11 cancers) have been shown. New associations of public health importance have been identified, including alcohol use with an increased risk of breast cancer. The results have been repeatedly confirmed by other studies, suggesting that efforts to minimize potential biases have been successful. CCS is a unique resource for cancer epidemiology; alternate systems have largely been useful in other areas. The continued introduction of new drugs to the market underscores the need for continuing data collection. CCS has data to address some of these issues immediately. CCS is the only system to have informative data on nonprescription drugs. A new component will involve the assessment of biomarkers of genetic susceptibility. DNA from CCS participants will be studied by polymerase chain reaction methods. This will serve to identify subgroups with particular exposures who are at increased (or decreased) risk of specific cancers by virtue of their inherited genotype, and to elucidate mechanisms; hypotheses concerning large bowel cancer and breast cancer will be tested in the next grant period.