What Is Hematology Oncology?

Hematology oncology is the field of blood disorders and cancer. Hematology concerns blood, blood disorders, and bone marrow disease, while oncology is the study of cancer. Also referred to as hematology/oncology, or heme/onc, this field is focused on diagnosing, treating, and preventing blood, bone marrow, and lymphatic system cancers. 

The field of hematology/oncology can involve many subspecialties as there are a variety of cancers and other blood disorders which exist. This article will review what hematology oncology involves, as well as who works in the field and what they treat. 

A doctor examines a person in a medical office

Jose Luis Pelaez Inc / Getty Images

Difference Between Hematology and Oncology

Although they are often paired, the fields of hematology and oncology can be two separate entities. Hematology involves the study of blood and diseases and disorders of the blood and bone marrow (the spongy tissue inside bones that produces blood cells).

Many blood diseases are cancerous, but there are also benign (noncancerous) blood disorders as well. Noncancerous blood disorders can include:

Although the term "benign" is used, in this setting it means noncancerous. Hematology disorders, even if not cancerous, can still lead to many symptoms and negatively affect someone’s life.

Oncology is the study of cancer. Cancers can start in any body system, which includes solid organs as well as the blood.

In treating hematologic cancers, the team may include specialists in hematology or in cancer, or medical doctors (M.D.s) who have a combined specialty of hematology and medical oncology (hematology/oncology).

Hematology/Oncology Clinics or Services

A service division or clinic may be called hematology/oncology in a medical practice or medical center. You may be referred to specialists there if you have cancerous or noncancerous hematologic conditions. Some hematology/oncology clinics or services also treat non-hematologic cancers.

What Do Hematologists Treat?

Hematologists are physicians who specialize in treating a variety of diseases that affect the blood system and bone marrow. These can include diseases such as bleeding and clotting disorders, as well as diseases that affect how blood cells are made. Some of these diseases are cancerous, and some are not.

What Do Oncologists Treat?

Oncologists are physicians who specialize in diagnosing and treating cancer. These cancers can include cancers of the blood and bone marrow (hematological cancers) but also cancers that develop in solid organs such as the breast, lungs, or liver. Some examples of solid tumor cancers include:

Examples of hematological cancers include:

  • Leukemia: Blood cancer affecting the white blood cells
  • Lymphoma: Cancer that affects the lymphatic system
  • Multiple myeloma: A type of blood cancer of the white blood cells that make antibodies (immune system proteins)

Training and Certification

There is a long process of training and certification to practice as a physician in hematology and medical oncology. To start, you must finish undergraduate and medical school. Then following successful completion of medical school, they enter an internal medicine residency.

Following residency, further training through a fellowship program in a hematology/oncology program is obtained. The educational process can take many years. Following fellowship, the physician can then become board certified.

The dual certification in hematology and medical oncology requires a minimum number of training hours, which can include successfully performing procedures such as bone marrow biopsies (removing a sample of tissue for analysis in a lab), knowing how to evaluate blood counts, imaging studies, and other diagnostic tests.

Other areas of hematology training focus on indwelling venous access devices (such as central lines), therapeutic phlebotomy (removing blood as a form of treatment for polycythemia or hemochromatosis), and apheresis (removing blood to take off the plasma and return the blood cells).

The training will include diagnosing and managing noncancerous hematologic disorders and many types of cancers (both hematological and non-hematological). They must be competent in treating the conditions systemically (throughout the body, such as with chemotherapy and medications).

You must pass an exam to become certified. To maintain certification, continuing education must be completed, or another certification exam can be taken.


Those who practice in hematology/oncology are specialized physicians. They can diagnose and treat both cancerous and noncancerous diseases that affect the blood, bone marrow, and lymphatic system.

A Word From Verywell

If you’ve been referred to see a specialist in hematology/oncology, you may be worried about what that means. Go to your visit with a list of questions so that you remember everything you wish to discuss. It may also be a good idea to bring someone with you to help you remember important points from your visit.

2 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.
  1. WVU Cancer Institute. Benign hematology.

  2. American Board of Internal Medicine. Hematology policies.

By Julie Scott, MSN, ANP-BC, AOCNP
Julie is an Adult Nurse Practitioner with oncology certification and a healthcare freelance writer with an interest in educating patients and the healthcare community.