An oncologist is a physician who specializes in oncology, the treatment of cancer. In some countries, oncologists are trained in a specific treatment type (i.e. medical oncology or radiation oncology), whereas in other countries oncologists are trained in both modalities. Surgical oncologists are surgeons with specialized training in performing cancer operations. Other types of oncologists are:

• neuro-oncologists: training in neurology with specialized treatment of chemotherapeutic drugs for cancers of the nervous system
• urologic oncologists: training in urologic surgery for tumors of the prostate, bladder, or kidney
• gynecologic oncologists: training in gynecologic surgery for tumors of the female reproductive organs