What Is Oncology?
For some people, the first time they hear the word “oncology” is after they’ve been told they have cancer. Understanding what it is and what it involves can help you feel more informed and prepared as you navigate your care.
What does oncology mean?
Oncology is the study of cancer. The word comes from the Greek word onkos, meaning tumor or mass. It is the branch of medicine that focuses on the diagnosis, treatment, and care of people with cancer.
Specialists trained in oncology provide care for people who are at risk for cancer, being treated for cancer, and living with cancer after treatment. Together, these specialists – along with other care providers like nurses, pharmacists, and social workers – make up your cancer care team.
What is an oncologist and what do they do?
An oncologist is a physician (medical doctor) who specializes in cancer. An oncologist leads a cancer care team in the care of people with cancer. Oncologists may:
- Diagnose cancer
- Make treatment recommendations and create treatment plans
- Carry out or oversee treatment
- Evaluate how the cancer responds to treatment
- Coordinate a patient’s care with other members of the cancer care team
- Provide follow-up care after treatment is completed
- Conduct research through clinical trials
Oncology specialties
While oncology is considered a “specialty” of medical care, there are specialized areas of oncology care, too.
Many oncologists focus on specialty areas based on how cancer is treated:
- Surgical oncologists treat cancer using surgery, including removing part or all of a solid tumor and nearby tissue. They can also perform certain types of biopsies to help diagnose cancer.
- Medical oncologists treat cancer using medication, including chemotherapy, immunotherapy, and targeted therapy.
- Radiation oncologists treat cancer with radiation therapy, which uses high-energy particles or waves to destroy cancer cells.
Some oncologists specialize in caring for specific groups of people or treating certain types of cancer. For example:
- Breast oncologists treat breast cancers in men and women.
- Geriatric oncologists work with people with cancer who are age 65 and older to provide the best care for older adults.
- Gynecologic oncologists treat cancers in the female reproductive organs, including the cervix, fallopian tubes, ovaries, uterus, vagina, and vulva.
- Hematologist oncologists treat blood cancers, such as leukemia, lymphoma, and myeloma.
- Neuro-oncologists treat cancers of the brain, spine, and nervous system.
- Pediatric oncologists treat cancer in children and teens. They may also treat adults with cancers that are more common in children.
- Thoracic oncologists treat cancers inside the chest area, including the lungs and esophagus.
- Urologic oncologists treat cancers in the genitourinary system, such as the bladder, kidneys, penis, prostate gland, and testicles.
When do I need an oncologist?
If you have been diagnosed with cancer. When a person is diagnosed with cancer, they will likely be referred to a medical oncologist. Depending on the specifics of your cancer and possible treatment plans, they may refer you to a surgeon or radiation oncologist, as well.
If cancer is suspected. In some cases, a surgical oncologist might be the first specialist a patient sees to diagnosis and stage a cancer. Sometimes when cancer is suspected but not diagnosed, a medical oncologist might also be involved. Some people with blood disorders that may or may not be cancerous might be referred to a hematologist oncologist.
After you have completed cancer treatment. Many people will continue seeing their oncologist for follow-up appointments to check for signs of cancer coming back and to manage any side effects from treatment. Over time, these visits are usually needed less often. You might also go back to only seeing your primary care doctor or other health care provider.
Other oncology professionals
In addition to oncologists, specially trained oncology nurses may give chemotherapy or other treatments, help manage symptoms and side effects, and provide patient education and support. Other health care professionals also provide specialized care and support for people with cancer, including:
- Advanced practice providers (nurse practitioners and physician assistant/associates)
- Patient navigators
- Oncology social workers
- Genetic counselors
- Clinical pharmacists
- Registered dietitians
- Radiologists
- Pathologists
- Mental health professionals
Learn more in Who Is the Cancer Care Team. Each member plays a vital role in your care and will work with you and your caregivers throughout your cancer journey.
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- References
Developed by the American Cancer Society medical and editorial content team with medical review and contribution by the American Society of Clinical Oncology (ASCO).
American Society of Clinical Oncology (ASCO). The oncology team. Accessed at cancer.net. Content is no longer available.
American Society of Clinical Oncology (ASCO). Types of oncologists. Accessed at cancer.net. Content is no longer available.
National Cancer Institute (NCI). What is oncology? Accessed at https://www.cancer.gov/publications/dictionaries/cancer-terms/def/oncology on July 22, 2025.
Last Revised: August 8, 2025
American Cancer Society medical information is copyrighted material. For reprint requests, please see our Content Usage Policy.
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