What Is an Oncologist?

There is more than one type of cancer doctor

Oncologists are physicians who specialize in the diagnosis and treatment of cancer. There are three main types of oncologists:

  • Medical oncologists who treat cancer with chemotherapy and other medications.
  • Surgical oncologists who treat cancer with surgery.
  • Radiation oncologists who treat cancer with radiation.

These specialists work as part of a multidisciplinary team which may include a pathologist, radiologist, primary care physician, geneticist, palliative care specialist, oncology nurse, and organ-specific oncologists.

Medical oncologists are licensed to practice after completing a residency in internal medicine and a fellowship in oncology. Surgical oncologists undergo a residency in general surgery before specializing in oncology. In addition to these specialties, there are no less than 15 other major oncology subspecialties.

Getting Good News from the Doctor A little girl with cancer is sitting with her stuffed animal at the doctors office and is waiting to hear about her chemotherapy treatment. A doctor is giving her good news.

FatCamera / Getty Images


Most people are referred to an oncologist if cancer is suspected or confirmed by a primary care doctor or other specialists. The oncologist will begin the investigation by performing additional tests to either confirm the diagnosis or characterize the malignancy.

This will be followed by cancer staging using imaging studies, lab tests, and other procedures.

Cancer stage is determined by six factors:

  1. The tumor location
  2. The type of cancer cell (such as basal cell carcinoma or squamous cell carcinoma)
  3. The size of the tumor
  4. Whether cancer has spread to nearby lymph nodes
  5. Whether it has spread (metastasized) to other parts of the body
  6. The grade of the tumor (a classification of how likely a tumor will grow based on the cell characteristics)

In addition to helping direct the treatment plan, cancer staging can predict survival times and the likely outcomes based on experience in the general population. Treatment of early-stage cancer may involve surgery or radiation, while advanced-stage cancer may require chemotherapy. In some cases, an organ-specific oncologist would be sought, particularly for malignancies that are rare, advanced, or aggressive.

Types of Cancer

The types of cancer an oncologist may see include:

Procedural Expertise

An oncologist manages a patient’s care throughout the course of the disease. This starts with the diagnosis and staging. Treatment is based on the results, with follow-ups scheduled to monitor response, identify relapse, or direct palliative care.


The tools used to diagnose cancer are extensive and involve lab tests, imaging studies, and other invasive or non-invasive procedures.

Among them:

  • Physical examinations are used to evaluate lumps, masses, lesions, or changes in skin color indicative of cancer.
  • Complete blood counts (CBC) can detect abnormalities in blood chemistry suggestive of leukemia while monitoring for the development of anemia, infection, or other complications during treatment.
  • Tumor markers tests are blood tests used to measure substances in the blood that could rise if there is cancer. These include the prostate-specific antigen test (PSA), which may be elevated in the blood in prostate cancer, and the CA-125 test, which can be detected in the blood with some types of cancer.
  • Flow cytometry evaluates cells suspended in fluid and is useful in diagnosing leukemia or lymphoma from a sample of blood or bone marrow.
  • Biopsy is the removal of a tissue or fluid sample from the body for microscopic evaluation. The sample may be obtained with fine-needle aspiration (FNA), core needle biopsy, cone biopsy, or surgery.
  • Imaging studies are used to locate or diagnose cancer and may include X-ray, computed tomography (CT), and magnetic resonance imaging (MRI). Nuclear medicine imaging, such as positron emission tomography (PET) uses radioactive tracers to detect changes in metabolism that can occur due to cancer.
  • Genomic testing can help identify the chromosomal characteristics of a tumor, which may help with selecting the most appropriate candidate drug therapies.

Many of these tests are used to diagnose cancer, measure your response to treatment, or monitor for disease recurrence after treatment.

Cancer Staging

The TNM system is the most widely used cancer staging system. Not all cancers rely on this system (including cancers of the brain, spinal cord, or blood) but most are loosely based on it.

In the TNM system:

  • The T refers to the size and extent of the primary tumor.
  • The N refers to the number of nearby lymph nodes with cancer.
  • The M refers to whether a cancer has metastasized.

Additional numbers and letters are used indicate the size and extent of a tumor, how many lymph nodes are affected, and how far the cancer has spread. Based on these characteristics, the oncologist can formulate a treatment plan.


Once a treatment plan is in place and you understand and agree to the recommendations, the appropriate specialist (or specialists) will begin to dispense therapy.

Medical oncologists treat cancer with medications such as chemotherapy, targeted therapies, immunotherapy, and hormonal therapy. They will also prescribe treatments to control your symptoms and side effects.

For many people, the medical oncologist will function as the primary specialist throughout the course of treatment, coordinating care with other doctors, while monitoring your overall response to treatment.

Radiation oncologists treat cancer with radiation therapy. They do so by mapping the area to be treated and calculating the dose and number of treatments needed. While radiation therapy has traditionally been used to eradicate cells left behind after surgery, stereotactic body radiotherapy (SBRT) is used to treat certain primary tumors or eliminate cancer in areas of metastasis. Radiation can also be used to ease pain during palliative care.

Surgical oncologists treat cancer with surgery. Some surgeons specialize in only certain cancer surgeries. For example, with prostate cancer, it is often a urologist who performs surgery, whereas otolaryngologists (ENT specialists) will typically treat head and neck cancers, and a thoracic surgeon will usually perform lung cancer surgery.

Post-Treatment Care

In addition to treatment, oncologists are trained to manage complications that commonly arise during and after therapy. After the completion of therapy, routine tests will be scheduled to evaluate the response. Even if the cancer is brought into remission, tests may be scheduled every three to six months for two to three years.

Test like the Oncotype DX can predict the likelihood of cancer returning.

Additionally, your oncologist will direct you to the appropriate services to aid in your physical and emotional recovery and teach you the survivorship skills to cope and thrive over the long term.


There are numerous subspecialties an oncologist can pursue with additional fellowship training. These include:

  • Breast oncology (cancers of the breast)
  • Bone and musculoskeletal oncology (cancers of bones and soft tissue)
  • Gastrointestinal oncology (cancers of stomach, colon, rectum, anus, liver, gallbladder, and pancreas)
  • Genitourinary oncology (cancers of the genitals and urinary tract)
  • Geriatric oncology
  • Gynecologic oncology (cancers of the female reproductive system)
  • Head and neck oncology (cancers of the mouth, nasal cavity, pharynx, and larynx)
  • Hemato-oncology (cancers of the blood and the use of stem cell transplants)
  • Nuclear medicine oncology (the diagnosis and treatment of cancer with radioactive pharmaceuticals)
  • Neuro-oncology (cancers of the brain)
  • Ocular oncology (cancers of the eye)
  • Oncopathology (the diagnosis of cancer in the laboratory)
  • Pain and palliative oncology (treating end-stage cancers to alleviate suffering)
  • Pediatric oncology
  • Thoracic oncology (cancers of lung, esophagus, and pleura)

Training and Certification

There are two similar but distinct education pathways to becoming an oncologist. They both start with obtaining a bachelor's degree in an accredited college or university and taking the Medical Competency Aptitude Test (MCAT). Based on your MCAT results, as well as a review of your transcripts, grade point average, and prerequisite coursework, you would enroll in and begin medical school.

While in medical school, you would spend the first two years mainly in the classroom and the second two years doing clinical rotations in various medical facilities to gain broad exposure to different fields of medicine.

Upon graduation, either as a doctor of medicine (MD) or doctor of osteopathic medicine (DO), you would decide if you want to pursue medical, radiation, or surgical oncology.

This is where the paths diverge:

  • Medical oncologists would complete a three-year internal medicine or pediatrics residency before applying to an oncology fellowship that would last for about three additional years.
  • Radiation oncologists would proceed to a radiation oncology residency program lasting five or six years.
  • Surgical oncologists would apply to a surgical residency program lasting five years. After the completion of residency, you would begin a fellowship in general surgical oncology lasting two to three years. Additional fellowships can be sought to specialize in specific fields of surgical oncology.

Licensing in most states requires you to pass the three parts of the United States Medical Licensing Examination (USMLE) and, in some states, a state board exam. Doctors with a DO degree can choose to take the Comprehensive Osteopathic Medical Licensing Examination (COMLEX) instead of the USMLE.

Medical oncologists may obtain board certification through the American Board of Internal Medicine (ABIM). Radiation oncologists can do so through the American Board of Radiology (ABR), while surgical oncologists would do the same through the American Board of Surgery (ABS).

Appointment Tips

If you are diagnosed with cancer, you will need to choose an oncologist with whom you can work over the long term. In many cases, it helps to find an oncologist who specializes in your type of cancer.

How to Choose an Oncologist

Before meeting an oncologist, take the time to verify his or her credentials. A good way to start is by doing an online search using the DocInfo website managed by the Federation of State Medical Boards. The site can provide you details about the oncologist's education, board certifications, states with active licenses, and any disciplinary or legal actions filed against the physician.

When meeting with an oncologist, ask questions to learn as much as you can about the practice and the doctor's experience. How long has the doctor been in practice? How many patients with your type of cancer does the doctor treat each year? 

You should also assess how you interact with the oncologist. Does the doctor listen and answer your questions fully and in a language you understand?

In the end, the best doctor-patient relationships are partnerships. If the connection doesn't feel right to you, do not hesitate to meet other oncologists or seek a second opinion.

Other Tips and Questions

The cost of cancer treatment can add to the stress you may already be experiencing. To help ease the anxiety, work with your health care team and insurance provider to determine what your out-of-pocket expenses will be, what copay or financial assistance programs are available, and which providers are in-network or out-of-network.

If you have a rare or specific type of cancer, your oncologist may even be able to enroll you in a clinical trial in which some of your medical costs would be covered.

Whatever cancer you are faced with, it is important to take control of your treatment by actively participating. Ask questions and gather all of the information you need to make an informed choice. Examples include:

  • Why are we doing these specific tests?
  • Why am I receiving this treatment?
  • Please explain how this treatment will help.
  • Why do you think that this is the best treatment for me?
  • What are the possible risks and side effects?
  • What is the response rate for the treatment?
  • Are there alternatives we should be considering?

Many oncology practices have in-office navigators who can direct you to the appropriate financial resources and subsidy programs.

A Word From Verywell

Oncology can be a rewarding and exciting career, with rapid advances in treatment options and the overall understanding of cancer. It can also be an extremely stressful profession. In addition to the long hours, an oncologist is responsible for the treatment of a disease that has no set course and is frightening to most people.

Burnout and "compassion fatigue" are common among oncologists, with only 34% reporting satisfaction with their work-life balance, according to a 2014 study in the Journal of Clinical Oncology.

It takes a special person to become an oncologist, one who has empathy and emotional resilience. For these doctors, the rewards can be considerable.

According to the annual Medscape Oncologist Compensation Report, oncologists in the United States earned an average of $363,000 across all specialties in 2018. Those practicing radiation or surgical oncology earned closer to $500,000 annually.

Frequently Asked Questions

  • What are oncology specialties?

    Oncologists can become specialized in specific fields of cancer treatment. Each of these requires completion of a corresponding fellowship. Examples of specialties include:

    • Medical oncology: the use of medication-based treatments to fight cancer, such as chemotherapy and immunotherapy
    • Radiation oncology: the use of ionizing radiation for cancer treatment
    • Surgical oncology: the use of surgical techniques to remove cancerous tissues or tumors
  • How many oncologists are in the U.S.?

    As of 2021, there are 13,146 active oncologists in patient care and 1638 oncology practices in the U.S.

  • How do you become an oncologist and how long does it take?

    Becoming an oncologist requires a college degree, followed by graduation from medical school. A person must then complete a residency in oncology, which typically lasts five years. Altogether, it takes about 13 years to become an oncologist.

15 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading

By Lynne Eldridge, MD
 Lynne Eldrige, MD, is a lung cancer physician, patient advocate, and award-winning author of "Avoiding Cancer One Day at a Time."