Guide to Acute Myeloid Leukemia

What Is It?

Acute myeloid leukemia (AML) is a fast-growing cancer that starts in a specific family of cells in your bone marrow. It affects how your blood cells develop. Though it can be hard to treat, sometimes it can be cured. AML is the second most common form of leukemia diagnosed each year, but adults under 40 rarely get it.

Who Gets It?

Most often, it's the result of a random mistake (called a mutation) in the DNA of your cells. Men are slightly more likely to get AML, as are people who have smoked for many years. If you've gotten chemotherapy or radiation, had leukemia before, or have a blood disorder, your odds are higher. Being around the chemical benzene also puts you at risk.

Where Blood Cells Come From

The billions of new blood cells your body makes every day start as stem cells in the spongy tissue inside your bones. A myeloid stem cell can become one of three things: Red cells that carry oxygen, white cells that fight infection, and platelets that form blood clots. You need the right balance of all three types for your blood to do its work.

What Goes Wrong?

If the DNA inside a stem cell gets damaged, the cell may not grow, work, or die correctly. These cells can get stuck at what's called the blast stage of development. When your body has too many blasts, they crowd out the other cells in your bone marrow, and your body can't make enough healthy blood cells of every type.

Symptoms

Without enough red blood cells, you may look pale or feel tired. Without enough white blood cells, you could get an infection that won't go away, or you might have fevers or night sweats. If your body isn't making enough platelets, you'll bruise easily or have tiny red spots on your skin. Your gums can swell or bleed. It's also common to lose weight even though you're not trying to.

Blood Tests

Your doctor will order a test called a CBC to count the number of each type of blood cell. If your white blood cell count is very high and the other types are very low, that suggests a blood cancer, possibly AML.

A blood smear test counts the number of blasts. Most people have some. But more than 20% blasts could mean you have AML.

Biopsy

A bone marrow sample can confirm a diagnosis of AML. The doctor will stick a needle into your hip bone to remove some marrow from the inside, or a little bit of both bone and marrow. (Don't worry -- they'll numb the area first. You'll feel mostly pressure.) They'll send the sample to a lab where a specialist will look for changes in these cells.

Subtypes of AML

Classifications are sort of like the stages used for breast, lung, and other solid tumor cancers. The kind of AML you have tells your doctor about how to treat it. The FAB system uses M0 through M7 to describe the type of cell the cancer came from and how developed it is. (M3 is also known as APL, acute promyelocytic leukemia.) The WHO system is based on things like specific DNA mutations, and it divides AML into groups with similar outcomes.

Is There a Cure?

The likelihood that your AML can be cured depends on the structure of the cancer itself as well as things about you. Older people tend to have more problems with their DNA and may have other health problems that get in the way of treatment. A previous blood disorder and having an infection or a white blood cell count greater than 100,000 when you're diagnosed aren't good. Your doctor will consider these "prognostic factors" when planning your treatment.

Induction Therapy

Because the disease gets worse quickly, treatment usually starts with a combination of chemotherapy drugs to make them more effective. The idea is to clear out the leukemia cells in your blood and bring down the number of blast cells in your bone marrow. It will take several days, and you'll have to stay in the hospital. The chemo drugs will also affect the normal cells in your bone marrow.

Remission

Afterward, your doctor will test your blood and bone marrow again. When less than 5% of the bone marrow sample is made up of blast cells, your blood counts are normal, and you have no symptoms, that's considered complete remission. In general, about 2 out of 3 people who get standard induction chemotherapy go into remission, although only about half of people over 60 do. Most people with APL will be in remission after induction chemo.

Consolidation Therapy

Once you've reached remission, the next phase of treatment is to get rid of any leukemia cells that may still be in your body, even if there are too few to be measured. The goal is to cure the cancer. Often you'll have more cycles of chemo in the hospital, but there are other treatments, too.

After consolidation, people with APL get low doses of chemo for months or years. This is the maintenance phase.

Targeted Therapy

These medicines are designed to find specific cells. For example, most AML cells have a protein called CD33 that's like a bright beacon saying "Attack here!" for the right treatment. Some therapies look for mutations such as FLT3 and IDH2. Targeted drugs can be used with or instead of chemotherapy for induction and consolidation. They might work when chemo doesn't.

Stem Cell Transplant

Your doctor may recommend a stem cell transplant for your consolidation therapy. First, you get high levels of chemo or radiation to kill all your stem cells, even the healthy ones. Then replacement stem cells get injected into your body so they can make cancer-free blood cells. If the new stem cells were taken from your body before treatment, that's an autologous transplant. If they came from a donor, that's allogenic.

Where It Can Spread

Sometimes AML cells can move into your spleen or liver, or into a man's testicles. Sometimes leukemia cells invade a bone and make it hurt. The cancer can also get into your spinal fluid and your brain. A procedure called a lumbar puncture, where a little fluid gets taken from your spine, can help your doctor find cancer in your central nervous system.

AML in Children

Fewer children than adults get this type of cancer, but their survival rate is much higher. Kids who are very young and those who have a lower white blood cell count at diagnosis have a better outlook.

Follow-up Care

Every few months or so you'll need to go back to the doctor or clinic for tests to make sure the cancer isn't growing again. It can be stressful to have a lot of checkups, blood tests, and scans, but it's worth it to catch a recurrence quickly. And the longer you're cancer-free, the more likely you are to stay that way. AML typically doesn't come back if there are no signs of it for a few years.

Relapsed or Refractory AML

Some leukemia cells can linger even after your treatment. This is called refractory leukemia. Other times, you may go into remission and then have the leukemia cells come back in your marrow. This is called a relapse. If you have refractory leukemia or a relapse, your doctor will weigh your age and other factors like genetic mutations and decide if you should try new drugs, chemo, or other therapies.