An oncologist is a doctor who specializes in treating patients with cancer, states the American Society of Clinical Oncology. There are three main types of oncologists that may treat a cancer patient, including a radiation oncologist, surgical oncologist and medical oncologist.
A medical oncologist helps treat and manage cancer with chemotherapy, according to the American Society of Clinical Oncology. A radiation oncologist specializes in the use of radiation therapy to kill cancer cells. A surgical oncologist specializes in the removal of cancerous tumors and the surrounding tissue. There are other types of oncology specialists, such as pediatric oncologists, gynecologic oncologists and hematologist-oncologists. A hematologist-oncologist specializes in cancers of the blood, such as leukemia.