Acute vs. Chronic Leukemia: What's the Difference?

The words acute and chronic describe how quickly a leukemia tends to progress. Acute leukemia develops fast. Very immature blood cells build up, and treatment usually needs to start soon after diagnosis. Chronic leukemia develops slowly. The cells look more mature, and the disease may be watched for a while before treatment begins. Pace does not decide how serious a leukemia is. Each type has its own outlook.

Leukemia is a cancer of the blood-forming tissue, mainly the bone marrow, where blood cells are made. In leukemia, abnormal white blood cells build up and crowd out healthy cells. That can affect the body's ability to fight infection, carry oxygen, and control bleeding.

In acute leukemia, the marrow makes many very immature cells, sometimes called blasts. They do not work properly, and they multiply quickly. Because the disease moves fast, acute leukemia usually needs prompt treatment. Symptoms can appear over days to weeks.

In chronic leukemia, the abnormal cells look more mature and build up gradually. Many people have few or no symptoms early on. The disease is often found on a routine blood test. Because it grows slowly, some chronic leukemias are watched closely at first. Treatment starts if the disease progresses or causes symptoms.

Leukemias are also grouped by which blood cell they start in:

• Lymphocytic (or lymphoblastic) leukemias start in lymphocytes.
• Myeloid leukemias start in myeloid cells.

Combine the two pairs and you get the four main types. Examples are acute myeloid leukemia and chronic lymphocytic leukemia. The full name tells you both the pace and the cell type.

The pace shapes the plan. Acute leukemia usually calls for prompt, active treatment. Chronic leukemia may be watched at first and treated later. But "slow" does not mean harmless. And "fast" does not settle the outlook. Each specific type has its own expected course and its own treatments. Helpful questions for your team: Which exact type do I have? Does it need treatment now, or can it be monitored? What tests will track how it is doing?

Any leukemia can leave you short of healthy blood cells. That means infection and bleeding can turn serious fast. This is true whether you are in treatment or being watched.

• Call 911 or go to an emergency department if you have bleeding that will not stop, are short of breath at rest, have chest pain, or become confused or hard to wake.
• Ring your hematology team at once, at any hour, if you have a temperature of 100.4°F (38°C) or higher, or shaking chills, while your white cell count is low or you are in treatment. With few infection-fighting cells, an infection can become life-threatening in hours. This is emergency care, not a call to make and then wait on. If nobody picks up quickly, go to an emergency department and tell them you are being treated for leukemia.
• Call your care team the same day if you have bleeding gums, frequent nosebleeds, or blood in your urine or stool.
• Call your care team within a day or two if you have new bruises you cannot explain, tiny red spots on your skin, night sweats, a lump in your neck, armpit, or groin, or tiredness that keeps getting worse.

If you are on watchful waiting rather than treatment, ask your team which changes should make you call before your next blood test.

• National Cancer Institute — Leukemia (Patient Version)
• National Cancer Institute — Acute Myeloid Leukemia Treatment (PDQ) Patient Version
• National Cancer Institute — Chronic Lymphocytic Leukemia Treatment (PDQ) Patient Version