Broad Objectives: to develop, evaluate, and test the utility of Medicare and Department of Veterans Affairs (VA) claims-based data to create a high quality National Cancer Surveillance System (NCSS) for the elderly U.S. population. Specific Aims: 1) Development--combine administrative data from Medicare and the VA for 12 important cancers; 2) Evaluation-- compare the quality of the data regarding incidence and stage of cancer at diagnosis in the NCSS with the same information reported by the SEER program in 1993; and 3) Utilization--(a) develop and analyze national incident rates for 12 cancers, as well as state specific rates, (b) describe treatment patterns for three cancer sites, and (3) model treatment outcomes for one cancer site. Relevance: Currently there is no uniform national system for reporting cancer incidence and stage of cancer at diagnosis. Such information would be extremely valuable for the planning and evaluation of cancer prevention and control interventions, as well as describing and evaluating treatment. Research Design: Medicare and Va administration data from 1989 to the present will be combined to create incident rates and determine the stage of cancer for elderly Medicare beneficiaries. The sensitivity, specificity and positive predictive values of the NCSS data will be determined using linked SEER-Medicare files. Treatment patterns for three cancers will be described using multinominal probit equations, and a model developed to describe treatment outcomes for one of them using OLS regression and/or Cox proportional hazards techniques.