Learn About Leukemia: Information, Facts & Overview

Leukemia (Cancer of the Lymphoblasts) — Abnormal white blood cells overcrowding normal cells resulting in Leukemia

Leukemia is cancer that forms in blood-forming tissue. The disease is characterized by the uncontrolled growth of blood cells, usually white blood cells in the bone marrow. White blood cells are a fundamental component of the body's immune response. Leukemia cells crowd out and replace normal blood and marrow cells.

Although many types of leukemia exist, some affect adults more commonly than others.

What causes leukemia?

The exact cause of leukemia isn't known, but researchers believe the disease develops due to mutations in the DNA of certain blood cells, caused by either genetic or environmental factors.

Some risk factors for leukemias that most commonly affect adults include:

Age, with people 65 and older more at risk
Long-term exposure to radiation or other carcinogenic chemicals, like benzene
Smoking
A family history of leukemia
Certain blood disorders, like polycythemia vera
Certain congenital syndromes, like Down syndrome and Fanconi anemia

Learn more about risk factors for leukemia

Who gets leukemia?

In the United States, an estimated 61,090 Americans will be diagnosed with leukemia in 2021, according to the American Cancer Society. Leukemia is diagnosed more often in men than in women. Although people of any age can develop the disease, it is most common in adults over 65 years old.

Leukemia types

Leukemia is categorized by the type of white blood cells affected and by how quickly the disease grows.

Types of leukemia include:

Acute lymphocytic leukemia (ALL), also known as acute lymphoblastic leukemia, affects the blood and bone marrow, and progresses rapidly.
Acute myeloid leukemia (AML), also known as acute myelogenous leukemia, acute myeloblastic leukemia, acute granulocytic leukemia or acute nonlymphocytic leukemia, affects the blood and bone marrow, and progresses rapidly.
Chronic lymphocytic leukemia (CLL) typically grows slowly, beginning in the lymphocytes of the bone marrow and then spreading to the blood.
Chronic myeloid leukemia (CML), also known as chronic myelogenous leukemia, begins in the blood-forming cells of the bone marrow and then spreads to the blood.
Hairy cell leukemia (HCL) is rare and progresses slowly, developing when bone marrow makes too many B cells.
Myelodysplastic syndromes (MDS) are related diseases that develop when the bone marrow produces too few functioning red blood cells, white blood cells or platelets, or any combination of the three.

Learn more about leukemia types

Leukemia symptoms

The symptoms of leukemia generally depend on the type of leukemia, how quickly it grows and at what stage the disease is diagnosed. Many signs of leukemia resemble flu-like symptoms.

Common leukemia symptoms include: