PDQ - National Cancer Institute"PDQ (Physician Data Query) is NCI's comprehensive cancer database. It contains summaries on a wide range of cancer topics; a registry of 8000+ open and 19,000+ closed cancer clinical trials from around the world; and a directory of professionals who provide genetics services. PDQ also contains the NCI Dictionary of Cancer Terms, with definitions for 6000+ cancer and medical terms, and the NCI Drug Dictionary, which has information on 1200+ agents used in the treatment of cancer or cancer-relate