Blood Cancer Comes in More than 100 Varieties: How They Differ & What They Have in Common

Your blood is made up of different kinds of cells:

• Red blood cells carry oxygen throughout your body
• Platelets help your blood clot after you're injured
• White blood cells help your immune system fight infections

All of these cells start out as immature cells, called stem cells, in bone marrow. Then they mature into fully functional blood cells.

When you have blood cancer, your blood cells either don't mature fully, or there are too many of them. The cells involved in blood cancer are almost always white blood cells.

Unique Features of Blood Cancer Types

How these cancers look and act can vary quite a bit. Some blood cancers grow slowly over a period of many years, while others spread quickly. Some cause intense symptoms like fatigue or night sweats, while others have such subtle symptoms that it's hard to know you have cancer at all.

It's even possible for one type of blood cancer to turn into another. For example, the rare myelodysplastic syndromes can turn into acute myeloid leukemia.

Related: The Different Stages of Cancer & What It Means for You

Given how differently each type of blood cancer looks and acts, it makes sense that different treatments work against them.

Slow-growing cancers might not need anything more than careful watching to see if they grow, while fast-moving ones will need more aggressive treatment with chemotherapy, targeted therapy, immunotherapy or other interventions. That's why it's important to get an accurate diagnosis. Knowing as much as possible about your blood cancer and its type will steer your doctor to the treatment that's most likely to work against it.

Related: Blood Cancer is Different from Other CancersSome Treatments Are, Too

There are three different types of blood cancer, each of which is further divided into several subtypes.

What Are the Three Types of Blood Cancer?

Leukemia, lymphoma, and myeloma are the three main types of blood cancer in adults and children.

Leukemia is a cancer of the early cells in bone marrow that grow into white blood cells. Problems arise when your body starts making too many of these cells. Because the new cells are abnormal and don't work like they should, they're of little help in protecting you against infections.

Under the main header of leukemia are four main subtypes, which are broken down based on the maturity of the white blood cells they affect, and the type of cells they start from:

• Acute myeloid leukemia (AML)
• Chronic myeloid leukemia (CML)
• Acute lymphocytic leukemia (ALL)
• Chronic lymphocytic leukemia (CLL)

What is acute myeloid leukemia? Dr. Mikkael Sekeres, director of the Cleveland Clinic Leukemia Program, explains.

Acute leukemia happens when the cancer cells are immature and can't do their job. Chronic leukemia is when most of the abnormal cells are mature, but they still don't work as well as healthy white blood cells.

Related: Acute Myeloid Leukemia: How Do I Make Treatment Decisions? 

Myeloid leukemias start in myeloid cells, the type of cells that become white blood cells, red blood cells, or platelets. Lymphocytic leukemias start from the cells that produce lymphocytes.

Lymphoma starts in a specific kind of white blood cell called a lymphocyte. These cells are part of your body's lymphatic system, a network of vessels and nodes that collect fluid, wastes, and germs like bacteria and viruses. In lymphoma, lymphocytes multiply to excess and build up in the lymph nodes and other tissues. These abnormal white blood cells make it difficult for your immune system to launch an effective attack against invading germs.

The two main lymphoma types are Hodgkin's lymphoma and non-Hodgkin's lymphoma. The “Hodgkin” in the name is a tribute to British doctor Thomas Hodgkin, who first described lymphoma in the 1800s. Within each of these two types are several more subtypes.

Non-Hodgkin lymphoma is the more common of the two types. It affects white blood cells called B-cells and T-cells. People with Hodgkin lymphoma have too many large abnormal cells called Hodgkin Reed-Sternberg cells.

Multiple myeloma starts in plasma cells, a type of white blood cell that makes antibodies. These immune system proteins help your body find and fight off germs. When plasma cells turn cancerous, you make far fewer antibodies, leaving you more susceptible to infections. Myeloma has several subtypes, each one based on which type of antibody (called immunoglobulin) it produces.

Related: The Revolution in Multiple Myeloma Treatment 

Rare Blood Cancer Types

A few blood cancers are less common, but still worth noting.

• Hairy cell leukemia is a form of leukemia that affects only about 1,000 people in the United States each year. It gets its name from the hair-like projections that jut out from the leukemia cells.
• Myelodysplastic syndromes (MDS) are a group of disorders that happen when stem cells in bone marrow don't develop into healthy, mature blood cells.
• Myeloproliferative disorders are another group of rare disorders in which the bone marrow produces large numbers of abnormal blood cells. These disorders include polycythemia vera, myelofibrosis, and essential thrombocythemia.

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