Medical oncologists are medical doctors who specialize in the diagnosis and treatment of cancer. They may be involved in determining the type and extent of cancer and providing treatments such as chemotherapy.

After treatment, oncologists provide follow-up care to monitor the progress of people who have had cancer and resume care for them if their cancer returns. Medical oncologists may further specialize in treating certain types of cancers or treating specific age groups, such as pediatric oncologists, who only treat children.

Medical oncologists are certified by the Royal College of Physicians and Surgeons of Canada.