What Is Hematology-Oncology: The Difference Between Hematology and Oncology Explained

Key Takeaways

• Hematologists specialize in blood disorders. Oncologists specialize in cancer. Hematologist-oncologists combine both disciplines to treat blood cancers.
• The most common blood cancers treated at RCCA are leukemia, lymphoma, and multiple myeloma. All three types have subtypes.
• RCCA also provides advanced care for benign blood conditions, including anemia, bleeding disorders, and blood-clotting disorders.
• RCCA hematologist-oncologists support patients through treatment and long-term management or recovery.

The Basics: Hematology, Oncology, and Hematology-Oncology Defined

Hematology, oncology, and hematology-oncology are closely related disciplines that frequently interact. Subtle differences set them apart, making physicians in each specialty uniquely qualified to handle slightly different cases. We break down the differences below:

What Is Hematology?

Hematology is the field of science and medicine that focuses on blood. Its name comes from the Greek word heme, which means blood. Hematologists are doctors who specialize in hematology. They study blood cells, blood-forming organs, such as bone marrow, and the lymphatic system. They also study cancers and non-malignant disorders that affect the blood and blood-forming organs.

The Scope of Hematology

Hematologists typically complete 12 to 14 years of education and training, including medical school, residency, and fellowship (subspecialty training). This background gives them an in-depth understanding of all types of blood and blood disorders. They apply this knowledge to providing diagnoses and cutting-edge treatments for a wide range of non-malignant blood disorders, and they may collaborate with oncologists to treat blood cancers as well.

What Is Oncology?

Oncology is the field of science and medicine that focuses on cancer. Its name comes from the Greek word onkos, which means tumor. Oncologists are doctors who specialize in oncology. They study how cancer forms and progresses to provide accurate diagnoses, staging, and treatments. They also help patients cope with the stress and anxiety that a cancer diagnosis can bring.

The Scope of Oncology

Like hematologists, all oncologists have completed medical school, a three-year residency, and a four-year fellowship. They have an in-depth understanding of solid tumors, such as breast cancer, lung cancer, colon cancer, and prostate cancer. Most oncologists also have a sub-specialty. Medical oncologists, for example, provide chemotherapy and targeted therapies such as immunotherapy. Other oncologists specialize in a certain type of cancer, such as gynecological cancers or brain tumors.

What Is Hematology-Oncology?

Many cancer types start in the blood or lymph systems. Even cancers that start as solid tumors can enter and spread through the bloodstream in a process called metastasis. For this reason, many hematologists complete additional training in oncology, and many oncologists expand their training into hematology. These doctors are known as hematologist-oncologists and are experts in blood cancers.

The Scope of Hematology-Oncology

Hematologist-oncologists are experts in both blood disorders and cancer. They work in both fields, using a wide variety of modalities to treat and manage symptoms related to blood cancers. They provide chemotherapy, targeted therapies, immunotherapy, and other proven treatments to control or eliminate cancer. They also conduct clinical research to learn more about these diseases, giving future physicians better tools to diagnose, treat, and prevent them.

	Hematology	Oncology	Hematology-Oncology
What It Covers:	The blood and circulatory system	Solid tumor cancers	Blood cancers
Conditions Treated:	Anemia Bleeding disorders Clotting disorders Deep vein thrombosis	Breast cancer Prostate cancer Lung cancer Colon cancer	Leukemia Lymphoma Multiple myeloma
Who You See:	Hematologist	Oncologist	Hematologist-Oncologist

What Blood Cancers Are Treated in Hematology-Oncology?

Malignant blood disorders start in the bone marrow or in the lymphatic system. A DNA mutation causes blood cells to multiply rapidly, crowding out healthy blood cells with abnormal ones that cannot perform their jobs correctly. Uncontrolled blood cancer prevents the bloodstream from fighting infection, carrying oxygen, and performing other essential roles, causing full-body function to decline.

The main types of blood cancers treated at RCCA include leukemia, lymphoma, and multiple myeloma. All three types begin in a similar way, and they have similar effects. They are differentiated by where they start and what types of blood cells they affect.

Leukemia

Leukemia begins in the bone marrow, which is the soft tissue inside bones where most blood cells are produced. A single blood cell develops a cancerous DNA change. This cell quickly multiplies, replacing the healthy white blood cells and bone marrow cells with leukemia.

Acute vs. Chronic Leukemia

Leukemias are categorized based on their rate of growth. Acute leukemias spread very quickly throughout the body, while chronic leukemias are slower to grow. Leukemias are also categorized by whether they affect lymphocytes or myeloid cells. Hematology oncologists use these two characteristics to identify leukemia as one of four types:

• Acute lymphocytic leukemia (ALL): The cancer, also known as lymphoblastic leukemia, affects lymphocytes and spreads quickly. It is the most common type of leukemia in children.
• Chronic lymphocytic leukemia (CLL): The cancer affects lymphocytes and spreads slowly. It is the most common type of leukemia in adults.
• Acute myeloid leukemia (AML): The cancer begins in the bone marrow and spreads quickly. It is a common type of leukemia, accounting for a third of all cases.
• Chronic myeloid leukemia (CML): The cancer begins in the bone marrow and spreads slowly but can accelerate without warning. It is rare, accounting for only 15% of all cases.

While acute leukemias are aggressive, they are also easily identifiable. Chronic leukemias, meanwhile, can exist for years before the patient experiences symptoms. Their silent nature makes them comparatively difficult to detect and treat.

Lymphoma

Lymphoma develops in the lymph nodes, which filter harmful substances from the body. It produces abnormal white blood cells (lymphocytes). Instead of fighting disease, the lymphocytes build up in the lymph nodes and form solid tumors that are felt as painless lumps under the skin.

Hodgkin Lymphoma

Hodgkin lymphoma appears most frequently in adolescents and young adults. It originates in lymph nodes in the upper body, such as the chest, neck, armpits, or groin. It produces large Reed-Sternberg cells that are identifiable under a microscope. For this reason, Hodgkin lymphoma is relatively easy to detect and diagnose, and treatment prognoses are often positive.

Non-Hodgkin Lymphoma Subtypes

Non-Hodgkin lymphoma is a broad umbrella for all lymphomas that do not include Reed-Sternberg cells. It covers over 100 subtypes, including mantle cell, diffuse large B-cell, and more, each with its own characteristics and behavior. Because non-Hodgkin lymphoma is so varied, it can be difficult to detect and treat early. Prognoses depend on the subtype and how early the cancer was diagnosed.

Multiple Myeloma

Multiple myeloma starts in the bone marrow and affects plasma cells, which produce the antibodies that help white blood cells identify disease. Cancerous plasma cells accumulate in the bone marrow, damaging the bone. They also produce faulty antibodies that cannot identify diseases accurately. The faulty antibodies build up in the kidneys and other organs, causing damage.

Other Blood Cancers

RCCA also provides treatment for myelodysplastic syndrome (MDS) and myeloproliferative neoplasms (MPNs), two less-common types of blood cancers. MDS is a fairly common disorder that prevents blood cells from fully maturing. MPNs are characterized by the overproduction of blood cells, causing thick blood that overwhelms the body. Both conditions can lead to leukemia if left untreated.

What Benign Blood Disorders Are Treated by Hematologists?

Not all visits to the hematologist are related to blood cancer. Hematologists also provide treatment for a wide variety of benign or non-cancerous blood disorders. Many benign hematology conditions are easy to manage once correctly diagnosed. RCCA offers treatment and management services for the following:

Anemia

Anemia is a group of benign blood disorders that cause a low red blood cell count. Without enough blood cells to transport oxygen and nutrients, organs cannot function as they normally would. The body becomes fatigued and may show signs of organ failure. Once detected, anemia is manageable with diet adjustments, medications, blood transfusions, and bone marrow transplants.

Iron-Deficient Anemia

Iron-deficient anemia is the most common type of anemia. It occurs when the body does not receive enough iron, which is a necessary component for producing red blood cells. Iron-deficient anemia can be caused by pregnancy, ulcers, cancer, or heavy menstrual bleeding.

Aplastic Anemia

Aplastic anemia occurs when the immune system attacks the stem cells that produce red blood cells. With these cells destroyed, the bone marrow cannot produce enough blood cells. Aplastic anemia can develop randomly or because of pregnancy, cancer treatments, or autoimmune disorders.

Sickle Cell Disease

Sickle cell disease is an inherited disorder that appears at birth. The disorder causes red blood cells to develop with an abnormal sickle shape instead of a healthy, flexible disc shape. The abnormal red blood cells die quickly, causing patients to experience a consistent shortage of red blood cells.

Bleeding and Clotting Disorders

Bleeding disorders and blood-clotting disorders are a group of conditions that affect how blood clots. Some cause too many blood clots, potentially leading to blockages. Others prevent clots from forming and can cause excessive bleeding. Both types can be successfully managed with medications or factor replacement therapy, preventing complications.

Hemophilia

Hemophilia is a genetic disorder caused by a lack of clotting factors. This can lead to prolonged bleeding after injuries, surgery, or a vaccination. Severe hemophilia may also cause sudden internal bleeding. The condition is rare and mostly inherited from parents, and it can range from mild to severe.

Thrombocytopenia

Thrombocytopenia occurs when the bone marrow does not produce enough platelets, which play a part in blood clotting. It significantly increases the risk of bruising and excessive bleeding. Thrombocytopenia is most common in patients with autoimmune diseases or who take certain medications.

Deep Vein Thrombosis

Deep vein thrombosis (DVT) is a common complication of clotting disorders. It occurs when a blood clot forms in a deep vein, typically in the pelvis, lower legs, or thighs. The clot blocks the vein, causing blood to pool in the leg. The clot can also loosen and travel to the heart or brain.

When Should You See a Hematologist-Oncologist?

Individuals are sent to a hematologist for several reasons. While it may be related to a serious disease like cancer, it is more often for evaluation. A person’s primary care physician may wish to draw upon the hematologist’s expertise to investigate something irregular, such as an abnormality in a routine blood test. Or, the individual may be experiencing symptoms of a blood disorder, such as:

• Fatigue
• Dizziness
• Shortness of breath
• Heart palpitations
• Excessive bleeding
• Nosebleeds
• Excessive clotting

In many cases, hematological testing will rule out a blood disorder. If one is diagnosed, however, the hematologist will have the in-depth knowledge to treat it. The hematologist will work with the patient’s primary care physician to develop a personalized treatment plan.

What Does a Hematology-Oncologist Do at RCCA?

RCCA’s doctors work with every aspect of blood disorder care. They accurately diagnose blood disorders, work with the patient’s care team to develop a treatment or control strategy, and support patients through long-term management or recovery.

The Diagnostic Process

The first stage of care is diagnosis. RCCA hematology-oncologists follow a careful process to identify or rule out blood disorders accurately. Some tests may be ordered by primary care doctors, while others are done by hematologist-oncologists. They include:

• Blood panels: A blood panel, also called a complete blood count (CBC), counts the number of cells and proteins in a blood sample to detect overproduction or shortages.
• Bone marrow biopsy: The hematologist uses a long needle to remove a sample of bone marrow. The sample is studied to look for damaged or cancerous cells.
• Medical imaging: An X-ray, computed tomography (CT), or magnetic resonance imaging (MRI) scan may be used to examine the bones for lesions caused by blood cancer.
• Genetic testing: A genetic test helps hematologist-oncologists detect genetic risk factors for cancer, as well as hereditary conditions such as sickle cell anemia.

Each successive test helps to rule out possibilities and narrow down to the correct diagnosis. The tests also provide valuable information about the patient’s condition and potential complications, helping physicians plan the most appropriate treatment.

Treatment Options Provided at RCCA

Once a blood disorder has been confirmed, the hematologist-oncologist begins planning a treatment. RCCA offers multiple advanced treatment modalities, including:

Chemotherapy

Chemotherapy is the most traditional treatment for blood cancers. It uses strong drugs that are highly toxic to cells that multiply quickly, especially cancer cells. The drugs travel throughout the patient’s circulatory system to kill cancer cells everywhere in the body. This systemic attack makes chemotherapy an effective solution for blood cancers.

Targeted Therapy

Targeted therapies are a form of precision medicine that attack cells with specific characteristics. Depending on the therapy, they might interrupt cancer cell production, disrupt signals that tell cancer cells to grow, or deliver chemotherapy directly to the malignant cells. This approach lets physicians target cancer cells directly without damaging healthy tissue.

Immunotherapy

Immunotherapy, including CAR-T cell therapy, is a type of precision medicine. The hematologist removes a sample of immune cells from the patient’s body, then modifies those cells with instructions to fight cancer. The immune cells are then injected back into the patient. Immunotherapy gives the patient’s own immune system the tools it needs to combat cancer directly.

Infusion Therapy

Infusion therapy is the preferred treatment for most benign blood disorders. It involves infusing the body with cells or proteins to replace what it cannot produce itself. For example, red blood cell infusions may be used to control anemia. Platelet infusions and factor replacements reduce clotting disorders by providing the body with what it needs to form blood clots.

Get Blood Disorder Care Near You in NJ, CT, MA, and the Washington, D.C., Area

If you have been referred to a hematologist-oncologist, it does not necessarily mean cancer. It only means that your primary care physician wants a second opinion. If a blood disorder is confirmed, then you can get high-quality care at RCCA. Regional Cancer Care Associates educates patients to help them avoid life-threatening cancer. RCCA specialists provide care to more than 30,000 new patients and 265,000 established patients each year. RCCA physicians offer patients innovative therapies, including immunotherapies and targeted therapy, cutting-edge diagnostics as well as access to approximately 300 clinical trials in community-based centers close to home.

Frequently Asked Questions About Hematology-Oncology

What is the difference between a hematologist and an oncologist?

Hematologists specialize in diagnosing and treating blood disorders. Oncologists specialize in diagnosing and treating cancer.

What does a hematologist-oncologist treat?

A hematologist-oncologist is a specialist who combines expertise in both hematology and oncology. They apply their knowledge to treat blood cancers such as leukemia, lymphoma, and multiple myeloma.

Is hematology-oncology only for cancer patients?

While hematologist-oncologists primarily treat blood cancers, they also provide diagnostic services and treatment for benign blood conditions. Getting referred to a hematologist-oncologist does not necessarily mean that you have cancer.

What blood tests do hematologist-oncologists use?

Hematologist-oncologists use a variety of blood tests, including complete blood count (CBCs) and blood cell examination, as well as bone marrow biopsy.

What is the difference between blood cancer and a blood disorder?

Blood cancer is a type of blood disorder that is characterized by rapid, disordered cell growth. All blood cancers are blood disorders, but not all blood disorders are cancerous. Many disorders, such as anemia and clotting disorders, are benign.

Do I need a referral to see a hematologist-oncologist?

Yes, you usually need a referral to see a hematologist-oncologist. If you think that you might have a blood disorder, talk with your primary care physician about getting a referral to RCCA.

How long does hematology-oncology treatment take?

The length of treatment depends on the condition being treated. Some blood disorders can be treated within a few months to a year, although follow-up appointments may be required to make sure that malignant conditions do not recur. Many blood disorders cannot be cured. Patients with chronic blood disorders can expect lifelong care to keep the condition under control.

What is a bone marrow biopsy, and does it hurt?

A bone marrow biopsy involves taking a sample of bone marrow for examination. It is used to diagnose blood cancers that begin in the marrow. The area around the biopsy site is numbed to prevent discomfort, but patients may feel some pain or pressure.

Can a hematologist-oncologist treat anemia?

Yes, a hematologist-oncologist can treat anemia. Not all types of anemia can be completely cured, but they can be managed to prevent complications and promote a high quality of life.

What should I expect at my first hematology-oncology appointment?

At your first hematology-oncology appointment, you will meet the hematologist-oncologist and discuss why you are there. You might talk about your symptoms or look at test results, depending on the reason for your referral. The hematologist-oncologist will request the appropriate diagnostic tests to narrow down possibilities and confirm your condition. Most hematology-oncology appointments rule out a blood disorder.