What is an Oncologist? Everything You Need to Know

There’s a famous quote from the late British journalist John Diamond that reads: “cancer is a word, not a sentence”. A better outlook on the disease can be achieved with early detection, regular screenings and finding an oncologist that’s right for you. Understanding this medical field, however, can feel complex and overwhelming. Fortunately, we’ve got you covered with a guide to answer all your questions around oncology and the types of cancer treatment available.

What Is an Oncologist

Oncologists are highly trained doctors specialized in treating cancer patients. Oncologists tend to patients during the full span of their disease, beginning with the diagnosis and through the treatment of their choice. Besides guiding patients through the ups and downs of such a process, oncologists also tend to the patient’s family, helping them understand each stage of the disease as well as the treatments available for their loved one. 

Types of Oncologists

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Cancer is a disease that affects people of all races, genders and ages. There are also more than 120 types of cancer so it’s easy to understand why there are so many oncology specialties out there. Besides treating cancer patients directly, oncologists can also take part in clinical research and teaching medical students. Some of the most common specialties in the field of oncology are:

Clinical Oncologist

A clinical oncologist is a specialist trained in prescribing chemotherapy and systemic therapies such as immunotherapy. Along with a primary physician, the clinical oncologist is the main medical authority for a cancer patient. They are the ones who manage and supervise cancer treatments from beginning to end. 

Surgical Oncologist

Surgical oncologists are general surgeons who specialize in diagnosing, staging (determining cancer stages) and removing cancerous tissue. Some of the procedures they perform are biopsies and surgeries to remove malignant tumors. They also perform exploratory surgeries to determine the stage of a tumor and how much the disease has spread. 

In some cancer patients, surgery may be the only required treatment. But in other cases, the procedure must be followed up by additional treatments such as chemotherapy or radiation. 

Pediatric Oncologist

Each year, an estimated 400,000 children and adolescents under 19 develop cancer. Pediatric oncologists play an important role for child patients since they are specially trained to care and keep them comfortable during their treatment. The good news is that, in the US, close to 80% of children with cancer survive oncology treatments. 

Gynecologic Oncologist

A gynecologic oncologist is an OB-GYN who is certified in diagnosing and treating cancer in female reproductive organs. Such forms of cancer include cervical, ovarian, vulvar, vaginal and uterine. Gynecologic oncologists also treat premalignant conditions which can lead to cancer such as cervical dysplasia (abnormal alterations in cells that appear on the surface of the cervix). 

Radiation Oncologist

More than half of cancer patients will receive radiation therapy at some point. Radiation oncologists are the highly qualified  specialists who apply it. The procedure consists of using high-energy particles of radiation to destroy cancer cells. Radiation oncologists usually work hand in hand with clinical oncologists, surgeons and other doctors to determine the best courses of action for specific cancer patients. 

Hematologist Oncologist

Hematologist oncologists diagnose, treat and prevent blood cancers and related diseases. They use a wide range of resources to diagnose these diseases including imaging and lab tests. Some blood cancers treated by hematologist oncologists include:

Blood cancers differ from other types of cancer in that they evolve inside of blood cells and may not cause visible tumors. Although some hematologist oncologists have experience in treating tumors, most don’t deal with operable cancers.

The role of the oncologist

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Although they are commonly associated with treating cancer patients, an oncologist’s work begins way before the disease is even diagnosed. Overall, his tasks can be classified as follows:


Preventive oncology focuses on key actions that can prevent cancer development or delay the progression of the malignant process. These measures can be taken on two levels:

  1. Primary cancer prevention: Focuses on identifying factors that cause cancer. These measures include eliminating alcohol and tobacco consumption, avoiding obesity, administering vaccines and practicing a healthy lifestyle.

  2. Secondary cancer prevention: Focuses on detecting cancer before symptoms appear, when  treatment can still be effective. This type of prevention encourages routine checkups.


Oncologists use one or several of the following approaches to diagnose cancer: 

  • Physical exam. During a physical exam, your doctor may feel areas of your body for lumps that may indicate cancer. He or she may also look for abnormalities, such as changes in skin color or enlargement of an organ.

  • Laboratory tests. Laboratory tests, such as urine and blood tests, may help your doctor identify abnormalities that can be caused by cancer. For instance, in people with leukemia, a common blood test called complete blood count may reveal an unusual number or type of white blood cells.

  • Imaging tests. Imaging tests allow your doctor to examine your bones and internal organs in a non-invasive way. Imaging tests used in diagnosing cancer include a computerized tomography (CT) scan, bone scan, magnetic resonance imaging (MRI), positron emission tomography (PET) scan, ultrasound and X-ray.

  • Biopsy. During a biopsy, your doctor collects a sample of cells for testing in the laboratory. Which biopsy procedure is right for you depends on the type of cancer and its location. In most situations, a biopsy is the only way to definitively diagnose cancer.


There are a number of options for treating cancer nowadays and many more are currently being researched. Some “local” treatments such as surgery and radiation therapy are used for treating tumors and targeting specific parts of your body. Others, such as drug treatments (chemotherapy, immunotherapy) are known as systemic because they target the entire body. Some of the most common cancer treatments are:

  • Surgery. Surgery is used to prevent, diagnose, stage and treat cancer. It can also relieve discomfort related to the disease. There are many types of cancer surgeries but the most common is the removal of the infected tissue.

  • Radiation therapy. Radiation is one of the most common treatments for cancer. It involves using intense energy beams that damage the DNA inside of cancerous cells, preventing their growth and blocking cell-division. Normal cells nearby can also be affected by this procedure but most can recover and regain their function. 

  • Chemotherapy. Although the word “chemotherapy” (therapy with chemicals) actually refers to any sort of medicine for any sort of ailment, most people associate it with cancer treatment. Also known as “chemo”, it works by stopping or slowing the growth of cancer cells. It can be used to cure cancer or to simply shrink tumors that cause pain. 

  • Immunotherapy. Immunotherapy uses parts of a patient’s own immune system to combat cancer. This can be done two ways. One is by stimulating the immune system to work more efficiently and destroy cancerous cells. The other is by synthesizing the chemicals that our immune system uses in a lab and then reusing them as medicine.

  • Targeted therapy. Targeted therapy is a type of cancer treatment that uses medicines designed to target cancerous cells without affecting healthy ones. It recognizes cancerous cells by identifying the genetic alterations which allow them to grow and multiply uncontrollably (which healthy cells lack).

  • Hormone therapy. Some types of cancer use hormones to grow. Hormone therapy blocks or alters these, delaying or stopping the growth of cancer cells completely. Also known as endocrine therapy, it’s used mainly for certain types of cancers such as breast and prostate which depend on sexual hormones to grow.

  • Stem cell transplants. High doses of chemo and/or radiation therapy tend to destroy a patient’s stem cells and can even cause bone marrow to stop producing them for a period of time. In other words, stem cells are destroyed by these treatments on purpose. Since our bodies require blood cells to function properly, stem cell transplants help “rescue” bone marrow by replacing the body’s ravished stem cells. This way, transplants allow doctors to use much higher doses of chemo and/or radiation to eliminate cancerous cells. 

Your health comes first!

Cancer is a terrible disease that affects millions of people in the US every year. Yet between 30 and 50% of all cases could be prevented by avoiding risk factors and implementing existing evidence-based prevention strategies. You can start by exercising on a regular basis, eating a healthy diet and attending regular check-ups. Understanding the information we have provided in this handy guide is also a step in the right direction.
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