Acute myeloid leukemia (AML) and chronic myeloid leukemia (CML) are both blood cancers of the bone marrow — the soft, spongy tissue in the center of your bones where blood cells are made. Leukemia occurs when white blood cells grow uncontrollably, interfering with the production of normal blood cells.

Although both types of leukemia affect myeloid white blood cells, they differ in how quickly they develop, the symptoms they cause, treatment approaches, and overall prognosis (outlook).

Types of Leukemia

Leukemia can be classified in two ways: how quickly it progresses — categorized as either acute or chronic — and the type of blood cells that are growing abnormally.

Acute vs. Chronic Leukemia

AML progresses rapidly and involves white blood cells that aren’t fully developed, called blasts. These cells do not function properly. CML progresses more slowly and involves more mature, but still abnormal, blood cells.

Myeloid Leukemia

Leukemia can arise from two types of blood-forming cells — myeloid and lymphoid cells. Because AML and CML originate from abnormal myeloid cells, they are classified as myelogenous leukemias. Myeloid cells can develop into:

• Red blood cells, which carry oxygen
• Platelets, which help with blood clotting
• White blood cells, such as neutrophils, basophils, eosinophils, and monocytes, which help fight infection

By comparison, lymphocytic leukemias, such as acute lymphocytic leukemia and chronic lymphocytic leukemia, cause the bone marrow to produce too many lymphocytes (B cells and T cells), which are key players in the immune system.

What Causes AML and CML?

Leukemia develops when mutations (changes) in the DNA of bone marrow cells disrupt normal cell growth, division, or death. These mutations can occur spontaneously throughout a person’s lifetime or result from exposure to certain chemicals, radiation or other environmental factors. The risk of developing leukemia increases with age due to the accumulation of genetic changes over time.

AML progresses rapidly and involves white blood cells that aren’t fully developed. CML progresses more slowly and involves more mature blood cells.

AML cells commonly have gene mutations that either prevent bone marrow cells from maturing or cause them to multiply uncontrollably. Examples of these genes include:

• FLT3
• c-KIT
• RAS
• IDH1 and IDH2
• TP53

In contrast, nearly all CML cells contain a genetic abnormality called the Philadelphia (Ph) chromosome. This occurs when parts of two chromosomes swap places, creating a fusion gene called BCR-ABL. This gene produces a protein called tyrosine kinase, which drives uncontrolled cell growth and division.

Who Gets AML vs. CML?

AML is more common than CML. The American Cancer Society estimates that in 2025, there will be more than 22,000 new cases of AML and more than 11,000 new cases of CML in the United States. Both AML and CML are more common in adults than in children.

Risk Factors

Certain factors can increase your risk of developing either AML or CML.

According to the American Cancer Society, risk factors for both AML and CML include:

• Older age
• Male sex
• Exposure to radiation

Additional factors have been linked specifically to AML but don’t appear to increase the risk of CML:

• Smoking
• Exposure to certain chemicals (such as benzene, a solvent found in industrial settings)
• Previous chemotherapy
• Blood disorders like myelodysplastic syndrome (a condition that affects bone marrow function)
• Certain genetic syndromes (such as Li-Fraumeni syndrome and Fanconi anemia)
• Family history of AML

People with Down syndrome are also at an increased risk of developing AML.

Symptoms of AML and CML

Shared symptoms of AML and CML include:

• Unintentional weight loss
• Fatigue (persistent tiredness that doesn’t improve with rest)
• Fever
• Night sweats
• Loss of appetite
• Bone pain

• Swelling or pain in the abdomen

Many AML and CML symptoms occur because of the high number of leukemia cells, which can crowd out healthy, functional cells. Having too few red blood cells can result in anemia (low levels of red blood cells), causing symptoms such as:

• Weakness
• Tiredness
• Shortness of breath

When you have too many blast cells and not enough functional white blood cells (particularly neutrophils), your risk of infection rises. If you don’t have enough platelets, your risk of bleeding and easy bruising rises.

Classification of AML and CML

Most cancers are classified into stages based on the size of the tumor and how far it has spread. AML and CML usually don’t form tumors, so their classification works differently than that of other cancers.

AML is most often treated with chemotherapy. People with CML typically receive tyrosine kinase inhibitors, a type of targeted therapy.

AML is classified into subtypes based on the cancer cells’ characteristics, including:

• Their appearance under a microscope
• Genetic abnormalities
• Blood cell counts

CML is classified by phases — chronic, accelerated, and blast. Compared with people who have chronic phase CML, people with accelerated or blast-phase CML have more leukemia cells. If CML progresses to the blast phase, the symptoms can be very similar to those of AML.

Treatments for AML and CML

Chemotherapy and targeted therapy are the main treatments for AML. Targeted therapy is the main treatment for CML. The type of treatment your doctor recommends depends on the subtype or phase of cancer you have, your age, and other factors. AML requires rapid treatment because it progresses very quickly.

Chemotherapy

The primary treatment for AML is often chemotherapy. Common chemotherapy drugs used to treat AML include:

• Azacitidine (Onureg) combined with venetoclax (Venclexta)
• Cytarabine
• Daunorubicin
• Decitabine (Dacogen) combined with venetoclax
• Fludarabine phosphate
• Idarubicin (Idamycin PFS)

In contrast, chemotherapy is rarely used to treat CML because targeted therapy tends to work better. Chemotherapy is typically used only in people who are resistant to targeted therapies.

Targeted Therapy

Targeted therapies attack a gene or specific protein inside or on the surface of the cancer cell. Because AML and CML are caused by different gene mutations, the targets are different.

About 90 percent of people with CML are still alive after five years. About 32 percent of those with AML are still alive after five years.

Venetoclax zeroes in on the BCL-2 protein. In addition, several AML drugs target gene mutations. These drugs can be taken with chemotherapy or used alone by people who are older or not strong enough to tolerate chemotherapy.

• People with a mutation in the FLT3 gene can use midostaurin (Rydapt), quizartinib (Vanflyta), or gilteritinib (Xospata).
• People with a mutation in the IDH1 gene can use ivosidenib (Tibsovo) or olutasidenib (Rezlidhia).
• People with a mutation in the IDH2 gene can use enasidenib (Idhifa).

These drugs may be used alone or with chemotherapy, particularly in older adults or those who cannot tolerate intensive chemotherapy.

Because almost all CML cells have the same mutation causing abnormal tyrosine kinase activity, certain targeted therapies inhibit this protein. Known as tyrosine kinase inhibitors (TKIs), these drugs are very effective and provide the first-line treatment for CML. TKIs often used first in CML include:

• Asciminib (Scemblix)
• Bosutinib (Bosulif)
• Dasatinib (Sprycel)
• Imatinib (Gleevec)
• Nilotinib (Tasigna)

Nilotinib (Danziten), a newer formulation of nilotinib for CML, can be taken safely with food. Others must be taken on an empty stomach.

Learn more about CML treatment advancements.

Immunotherapy

Immunotherapies boost the immune system to help fight or destroy cancer cells. More research is needed to find out how immunotherapies can treat AML.

Interferon is a form of immunotherapy that can treat CML by slowing the division of cancer cells.

Outlook for AML vs. CML

People with CML often have a better prognosis (outlook) than those with AML. According to Cleveland Clinic, about 90 percent of people with CML and about 32 percent of people with AML survive for five years or more after diagnosis.

If you have AML or CML, your individual outlook will depend on several factors, including your age, overall health, response to treatment, and specific genetic mutations. Talk to your doctor or cancer care team to better understand your prognosis and treatment options.

Talk With Others Who Understand

MyLeukemiaTeam is the social network for people with leukemia and their loved ones. On MyLeukemiaTeam, more than 20,000 members come together to ask questions, give advice, and share their stories with others who understand life with leukemia.

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