This application responds to the need for Operations/Data Management and Statistical Centers for RFA CA-93-01 that will become part of the ongoing Radiology Diagnostic Oncology Group (RDOG). The proposed centers will continue to be based at the American College of Radiology and Harvard Medical School respectively. This application requests continued support for several tasks including the following 1) to support investigators in the design, development and implementation of the initial protocol; 2) to work with them in the design, development and implementation of data collection mechanisms; 3) to continually monitor and verify protocol compliance and data completeness (including follow-up information); 4) to design and perform statistical analyses of the data and to generate relevant reports; 5) to address methodological issues arising in the design and analysis of collaborative studies of this sort; and 6) to estimate the cost implications associated with the use of stereotactic techniques in the initial diagnostic evaluation of asymptomatic women. The Centers will also participate in the preparation of abstracts and manuscripts based on protocol findings.