AML is a blood cancer where bone marrow makes too many immature white blood cells

Acute myeloid leukemia (AML) is a type of blood cancer that starts in bone marrow — the soft tissue inside bones where blood cells form. In AML, the bone marrow produces abnormal myeloid cells (a type of white blood cell) much faster than normal. These immature cells, called blasts, crowd out healthy blood cells and spill into the bloodstream. Unlike chronic leukemias that develop slowly, AML develops quickly, which is why it is called "acute."

The problem starts when a single bone marrow cell develops a genetic change that makes it divide uncontrollably. That one cell multiplies into millions of identical abnormal cells. Because these blasts are immature and do not work like normal white blood cells, they cannot fight infection. At the same time, they take up space where healthy red blood cells, platelets, and normal white blood cells should grow. This causes anemia (too few red blood cells), bleeding problems (too few platelets), and infection risk (too few working white blood cells).

AML can develop in children and adults, but it is more common as people age. It accounts for about 80 percent of acute leukemias in adults. The disease is not inherited — it happens when a cell in the bone marrow acquires a mutation during a person's lifetime, not something passed down from a parent.

Key Takeaways

  • AML occurs when bone marrow produces too many immature myeloid cells that cannot function normally and crowd out healthy blood cells.
  • The disease develops quickly (acute), which is why symptoms often appear suddenly and treatment usually begins within days of diagnosis.
  • Low counts of healthy red blood cells, platelets, and normal white blood cells cause the main symptoms: fatigue, bleeding, bruising, and frequent infections.
  • Diagnosis requires a bone marrow biopsy and blood tests that show the type and genetic features of the leukemia cells, which guide treatment decisions.
  • Treatment typically involves chemotherapy, and newer options like targeted drugs and stem cell transplant may be used depending on age, overall health, and the specific genetic changes in the leukemia cells.

How AML develops in the bone marrow

Bone marrow is a factory for blood cells. Normally, stem cells in the marrow divide in a controlled way: some copies stay as stem cells, and others mature into red blood cells, platelets, or white blood cells. Each type of cell has a job and a lifespan. When a cell's job is done, it dies and is replaced by a new one.

In AML, a myeloid stem cell or early myeloid cell acquires one or more genetic mutations. These mutations tell the cell to divide without stopping and to ignore the signals that normally tell a cell to mature or die. The cell becomes a blast — an immature cell that divides rapidly but never finishes maturing. One mutated cell becomes two, two become four, and within weeks or months, the marrow is packed with millions of identical blasts.

Because blasts take up physical space in the marrow, there is less room for normal blood cell production. Red blood cells drop, causing fatigue and shortness of breath. Platelets drop, causing easy bruising and bleeding. Normal white blood cells drop, leaving the body unable to fight infection. The blasts also leak into the blood, which is how doctors see them under a microscope and confirm the diagnosis.

Symptoms that appear suddenly

AML symptoms often come on fast — sometimes over days or weeks — because the disease progresses quickly. The most common symptoms reflect low blood cell counts. Fatigue and weakness happen because there are not enough red blood cells to carry oxygen. Shortness of breath, dizziness, and pale skin are also signs of anemia.

Bleeding and bruising occur because platelet counts drop. A person might notice nosebleeds, bleeding gums, heavy menstrual bleeding, or bruises that appear without injury. Petechiae — tiny red or purple spots under the skin — are also common and are caused by bleeding from small blood vessels.

Frequent infections, fever, and chills happen because the abnormal white blood cells do not work. Even though the white blood cell count may be high, most of those cells are useless blasts. A person might develop pneumonia, urinary tract infections, or other serious infections that seem to come out of nowhere.

Other symptoms can include bone or joint pain (from the marrow working overtime), swollen lymph nodes, an enlarged spleen or liver, and sometimes a rash. Some people have no symptoms and discover AML by accident during a blood test for something else.

Genetic changes that define AML subtypes

Not all AML is the same. Doctors now classify AML based on the specific genetic mutations present in the leukemia cells. These mutations matter because they affect how aggressive the disease is and which treatments work best.

Some common genetic changes include mutations in genes like FLT3, NPM1, TP53, and IDH1/IDH2. Certain mutations, like t(15;17) — a rearrangement of chromosomes 15 and 17 — define a subtype called acute promyelocytic leukemia (APL). APL is actually one of the most treatable forms of AML because it responds well to a drug called all-trans retinoic acid (ATRA) combined with arsenic trioxide.

Other mutations predict whether AML will be harder to treat. For example, TP53 mutations are associated with worse outcomes, while NPM1 mutations without FLT3-ITD mutations are associated with better outcomes. Genetic testing is done on the leukemia cells at diagnosis so doctors can predict how the disease might behave and choose the most effective treatment.

How AML is diagnosed

Diagnosis starts with a blood test that shows abnormal cells. If a doctor sees blasts in the blood or suspects leukemia based on symptoms and blood counts, the next step is a bone marrow biopsy. This is a procedure where a needle is inserted into the hip bone (usually) to remove a small sample of marrow. The sample is examined under a microscope and tested in a lab.

The bone marrow sample shows how many blasts are present. AML is diagnosed when blasts make up 20 percent or more of the cells in the marrow (or blood). The sample is also sent for flow cytometry, a test that identifies the exact type of myeloid cell involved and looks for genetic mutations.

Additional tests include a chest X-ray to check for infection or leukemia in the lungs, and sometimes a spinal tap to see if leukemia cells are in the fluid around the brain and spinal cord. Blood tests measure kidney and liver function, which matters because treatment can affect these organs.

Risk factors and who gets AML

AML can develop in anyone, but certain factors make it more likely. Age is the strongest risk factor — most cases occur in people over 65. However, AML also occurs in children and younger adults.

Prior chemotherapy or radiation therapy for another cancer increases the risk of developing AML years later. Smoking, heavy alcohol use, and exposure to benzene (a chemical in some industrial settings) are linked to higher risk. People with certain inherited blood disorders, like Fanconi anemia or Bloom syndrome, have a higher lifetime risk of AML.

Some people develop AML from a pre-existing blood disorder like myelodysplastic syndrome (MDS), where bone marrow does not make enough normal blood cells. In these cases, the MDS gradually transforms into AML over months or years.

Most people who develop AML have no family history of leukemia and no known exposure to a risk factor. The genetic mutations that cause AML are acquired during a person's lifetime, not inherited from parents.

Treatment approaches and what comes next

Treatment for AML usually begins within days of diagnosis because the disease progresses rapidly. The main treatment is chemotherapy, typically a combination of drugs given intravenously. The standard regimen for many years was cytarabine and daunorubicin, often called "7+3" because it is given over 7 and 3 days respectively.

Newer chemotherapy drugs and targeted therapies are now available. For older adults or those too frail for intensive chemotherapy, lower-dose chemotherapy or drugs like azacitidine may be used. Targeted drugs like FLT3 inhibitors, IDH inhibitors, and venetoclax (combined with azacitidine) are used when specific genetic mutations are present.

For younger, healthier patients, treatment often includes a stem cell transplant (also called a bone marrow transplant) after the initial chemotherapy. A transplant replaces the diseased marrow with healthy stem cells from a donor, which can provide a better chance of long-term remission.

Remission means the leukemia is no longer detectable in the blood or bone marrow. However, AML can return, which is why follow-up care and monitoring continue for years. Treatment decisions depend on age, overall health, genetic features of the leukemia, and whether this is a first diagnosis or a relapse.

Frequently Asked Questions

Is AML the same as ALL (acute lymphoblastic leukemia)?

No. AML and ALL are both acute leukemias, but they start in different types of blood cells. AML starts in myeloid cells, while ALL starts in lymphoid cells (which become B and T cells). They have different genetic mutations, different treatment approaches, and different outcomes. ALL is more common in children, while AML is more common in adults.

Can AML be cured?

Some people with AML achieve long-term remission or cure, especially younger patients and those with favorable genetic mutations. Cure rates vary widely based on age, genetics, and response to treatment. Older adults and those with unfavorable mutations have lower cure rates but can still achieve remission and live for months or years. Your doctor can discuss the realistic goals of treatment based on your specific situation.

What is the difference between AML and MDS?

MDS (myelodysplastic syndrome) is a disorder where bone marrow does not make enough normal blood cells, but blasts are less than 20 percent of marrow cells. AML is diagnosed when blasts reach 20 percent or higher. MDS can transform into AML over time, but they are separate diagnoses with different treatment approaches.

Does AML run in families?

AML itself is not inherited. The genetic mutations that cause AML happen in a single cell during a person's lifetime and are not passed to children. However, some rare inherited conditions (like Fanconi anemia) increase the risk of developing AML. If you have a family history of leukemia, talk to your doctor about whether genetic counseling is appropriate.

How quickly does AML progress?

AML progresses rapidly — symptoms often appear over days to weeks, and without treatment, the disease can become life-threatening within weeks to months. This is why diagnosis and starting treatment quickly are important. The exact speed depends on how many blasts are present and how fast they are dividing.