What Is an Oncologist?

Medically Reviewed by Sabrina Felson, MD on July 17, 2023
5 min read

Oncologists are doctors who diagnose and treat cancer. They often act as the main healthcare provider for someone with cancer—designing treatment plans, offering supportive care, and sometimes coordinating treatment with other specialists. 

Oncology is the study of cancer. Oncologists specialize in managing and treating patients throughout the course of the disease, which involves:

  • Confirming a patient’s initial diagnosis
  • Explaining the cancer diagnosis and stage
  • Providing all possible treatment plans and offering recommendations
  • Overseeing the course of treatment
  • Helping patients manage symptoms and side effects of both the disease and the treatment plan

Oncologists typically have a specialty within the field, so they often expand a patient’s team to include the right doctors for a chosen treatment plan. 

Hematology oncologists are board-certified to practice hematology as well, treating patients with blood conditions including:

  • Anemia, a condition that results from a shortage of red blood cells
  • Sickle cell disease, an inherited blood disorder that can affect circulation
  • Different types of thrombosis, which occur when blood clots block blood vessels

Surgical and radiation oncologists are for assistance in diagnosis and treatment when surgery or radiation therapy is needed. Medical oncology would always be involved. 

Other oncology specialists focus on treating cancer in specific areas of the body. For example, gynecologic oncologists treat uterine, ovarian, and cervical cancers, while a hematologist-oncologist focuses on blood cancers. There are also pediatric oncologists who specialize in cancers common in children and teenagers. 

As medical doctors, oncologists’ study of cancer and blood disorders begins in medical school, after which paths diverge depending on a doctor’s chosen specialty. 

After completing medical school, oncology students:

  • Advance to a two- to five-year residency program, usually in internal medicine or surgery
  • Obtain their medical license and pass required board certification exams
  • Complete graduate or fellowship program in a chosen oncology specialty 
  • Pass subsequent licensing exams 

Your general practitioner or family doctor may refer you to an oncologist if they want the opinion of an expert in a specific field or can’t determine a cancer diagnosis. This intent is to narrow down—and rule out—potential causes of an issue so that you get the best course of treatment possible.

Your doctor might refer to you an oncologist to:

Test an Unusual Growth or Lump

Doctor’s offices aren’t usually equipped to diagnose a cancerous tumor, so they’ll refer you to an oncologist for further testing. Most suspected tumors are benign, or harmless, but this referral helps the doctor:

  • Ensure your peace of mind with a negative test
  • Rule out cancer as a cause of any symptoms you’re experiencing
  • Catch a potentially malignant, or harmful, tumor in its early stages—when treatment options are most successful
  • Direct the best possible care in the event of a positive test result

Provide Cancer Treatment

If you have a confirmed cancer diagnosis, you’ll be referred to an oncologist who will review your case individually, explain all of your treatment options, and offer their recommendation.

Depending on the cancer, its stage, and any potential health complications, this plan could include:

  • Radiation to slow a tumor’s growth without damaging healthy tissue
  • Surgery to physically remove a tumor
  • Targeted therapy to limit a tumor’s spread to other areas of your body
  • Chemotherapy treatment that destroys cancer cells

Get a Second Opinion

Cancer is a complex disease, and its treatments continue to evolve. Asking for another oncologist’s evaluation is common practice, especially that of an expert in a specific cancer or body part.

This second opinion can help to:

  • Confirm a diagnosis with a specialist
  • Learn additional details about a cancer’s type and stage
  • Explore more treatment options
  • Understand how the cancer affects other parts of your body
  • Find clinical trials available for you

Diagnose and Treat Blood Disorders

Many oncologists also specialize in hematology—the study and treatment of diseases related to the blood.

Your doctor may refer you to a hematology-certified oncologist for treatment if you have:

  • Symptoms of anemia, like brittle nails, a swollen tongue, an enlarged spleen, heart problems, or fatigue
  • Symptoms of sickle cell disease, like frequent infections, swollen hands and feet, vision problems, or severe episodes of pain
  • Symptoms of thrombosis, like swelling, pain, discoloration, or warmth in the affected area

Hematology oncologists also treat patients with clotting disorders like hemophilia, von Willebrand disease, and Thalassemia as well as cancers of the blood like lymphoma and leukemia.

Your first visit to an oncologist is a consultation. Ultimately, the doctor’s goal is to identify—or rule out—if and where cancer is present, establish an accurate diagnosis, and provide you with the best resources to overcome your condition.

During this initial appointment, the oncologist will perform a thorough physical examination and take the time to learn more about your medical and family history. Make sure to bring all of your available medical records, including a list of any medications or supplements you take. 

The oncologist will also review any scans and tests you’ve already had, and if necessary, perform additional tests. This generally starts with the oncologist examining your blood, urine, and other bodily fluids for high or low levels of certain substances that could be signs of cancer or blood disorders. They may also run visual imaging tests like CT scans, MRIs, PET scans, or ultrasound exams.

If cancer is suspected, oncologists usually need to perform a biopsy to confirm test results.

Depending on the area in question, there are different biopsy methods to retrieve a small tissue sample. The oncologist’s team—which includes a pathologist—then studies the sample to see if it contains cancer cells. 

If your oncologist confirms a cancer or blood disorder diagnosis, their next steps are to:

  • Inform you of all treatment options and offer their recommendations
  • Discuss fears and anxieties you may have
  • Put together the right team of specialists to deliver a comprehensive treatment plan
  • Offer an early prognosis, or basic prediction of your recovery timeline

Oncologists will also answer any questions you have, which could include: