The National Cancer Data Base (NCDB), a joint program of the Commission on Cancer (CoC) of the American College of Surgeons (ACoS) and the American Cancer Society (ACS), is a nationwide oncology outcomes database for more than 1,500 Commission-accredited cancer programs in the United States and Puerto Rico. Some 70 percent of all newly diagnosed cases of cancer in the United States are captured at the institutional level and reported to the NCDB. The NCDB, begun in 1989, now contains approximately 29 million records from hospital cancer registries across the United States. Data on all types of cancer are tracked and analyzed. These data are used to explore trends in cancer care, to create regional and state benchmarks for participating hospitals, and to serve as the basis for quality improvement.