Following the Institute of Medicine's 2009 report on the national priorities for comparative effectiveness research (CER), funding for support of CER became available in 2009 through the American Recovery and Re-investment Act. The Centers for Disease Control and Prevention (CDC) received funding to enhance the infrastructure of population-based cancer registries and to expand registry data collection to support CER. The CDC established 10 specialized registries within the National Program of Cancer Registries (NPCR) to enhance data collection for all cancers and to address targeted CER questions, including the clinical use and prognostic value of specific biomarkers. The project also included a special focus on detailed first course of treatment for cancers of the breast, colon, and rectum, as well as chronic myeloid leukemia (CML) diagnosed in 2011. This paper describes the methodology and the work conducted by the CDC and the NPCR specialized registries in collecting data for the 4 special focused cancers, including the selection of additional data variables, development of data collection tools and software modifications, institutional review board approvals, training, collection of detailed first course of treatment, and quality assurance. It also presents the characteristics of the study population and discusses the strengths and limitations of using population-based cancer registries to support CER as well as the potential future role of population-based cancer registries in assessing the quality of patient care and cancer control.