This phase I SBIR proposal will investigate the feasibility of conducting larger studies to determine whether the CA 25 immunoradiometric assay (IRMA), which measures tumor-associated antigenic determinants in serum, will be useful for early detection of ovarian cancer among asymptomatic women. The aims of the present investigation will be to: (1)\formulate a final protocol for a larger study; (2)\develop methods to standardize data, evaluation of data and subjects, followup, and study end points; (3)\make provisions for human subject committee requirements, subject registration and followup, collection and forwarding of samples and data, checking data for compliance, maintaining security of data, keeping investigators informed of study changes, developments, and outcomes, and analyzing data and reporting final results; (4)\identify an appropriate study population; (5)\assemble a group of investigators willing to enter subjects and follow the protocol; and (6)\gather preliminary performance data on the CA 125 IRMA to justify proceeding with a larger study. The principal end points of the phase I study will include final protocols, companion forms, a clear plan to proceed to tne next phase, and publications resulting from performance data collection. These results should also provide a model for future evaluation of serum assays for such purposes. (5)