In the National Cancer Act of 1971, the Director of the National Cancer Institute (NCI) was given a mandate to "Collect, analyze, and disseminate all data useful in the prevention, diagnosis, and treatment of cancer, including the establishment of an International Cancer Research Data Bank (ICRDB) to collect, catalog, store, and disseminate insofar as feasible the results of cancer research undertaken in any country for the use of any person involved in cancer research in any country" (National Cancer Act of 1971, S 1828, 92nd Congress, 1st Sess (1971)). In subsequent legislation, the audience for NCI's information dissemination activities was expanded to include physicians and other healthcare professionals, patients and their families, and the general public, in addition to cancer researchers. The Institute's response to these legislative requirements was to create what is now known as the Physician Data Query (PDQ®) cancer information database. From its beginnings in 1977 as a database of NCI-sponsored cancer clinical trials, PDQ has grown to include extensive information about cancer treatment, screening, prevention, supportive and palliative care, genetics, drugs, and more. Herein, we describe the history, editorial processes, influence, and global reach of one component of the PDQ database, namely its evidence-based cancer information summaries for health professionals. These summaries are widely recognized as important cancer information and education resources, and they further serve as foundational documents for the development of other cancer information products by NCI and other organizations.