Chemotherapy for acute myeloid leukemia

Chemotherapy ("chemo") is the use of drugs to kill or control cancer cells. Usually the drugs are given into a vein or by mouth or put into the fluid around the brain and spine (CSF). Except when given into the CSF, these drugs enter the bloodstream and go throughout the body. Chemo for acute myeloid leukemia (AML) usually involves 2 or 3 anti-cancer drugs.

Treatment of AML is divided into 2 phases:

• Induction (or remission induction)
• Consolidation (post-remission)

For some types of AML, there is a 3^rd phase: maintenance.

Induction

The goal of this first phase is to clear the blood of leukemia cells (blasts) and to reduce the number of blasts (very immature cells) in the bone marrow to normal. It usually involves treatment with 2 or 3 chemo drugs that are given while the patient is in the hospital. It takes about a week to give the chemo, and then often the patient stays in the hospital for a few weeks longer. In rare cases where the leukemia has spread to the brain or spinal cord, chemo may be given into the CSF as well.

During this time and in the weeks right after, the patient's blood cell counts will be very low. The doctor will take measures to protect against problems. If one week of chemo does not kill most of the cancer cells (bring about a remission), more chemo may be needed. The success rate for induction varies widely and depends on each person's own case.

Induction usually does not kill all of the leukemia cells. Without more treatment, called consolidation, the leukemia is likely to return in a few months.

Consolidation (post-remission) therapy

While the first phase of treatment usually kills nearly all of the cancer cells, there may still be a small number of "hidden" leukemia cells. The purpose of the second phase is to kill these cells and keep the cancer from coming back (relapsing). The options for consolidation treatment are either more chemo or a stem cell transplant (described later). Three years after this treatment, about 45% of patients younger than 60 years old will not show any signs of leukemia.

Doctors look at several factors when recommending what type of consolidation treatment might be best for a patient. These factors include:

• How much chemo it took to bring about a remission
• Whether there is a stem cell donor (brother, sister, or unrelated donor) who matches the patient's tissue type
• Whether it looks as if leukemia-free bone marrow stem cells can be collected from the patient
• Whether the prognostic factors are good or poor
• The patient's age. Older patients may not be able to take some of the severe side effects that can happen with high-dose chemo or stem cell transplants.
• What the patient wants to do

Stem cell transplants have been found to reduce the risk of leukemia coming back more than standard chemo, but they are also more likely to cause serious problems, and there is an increased risk of death from this treatment. Because most studies of stem cell transplants have involved patients who tend to be younger and in better health, their better survival might not be due to the stem cell transplant. The exact role of transplant in treating AML is not clear. Research into this is going on.

Treating frail, older adults

Treatment of AML in people under 60 is fairly standard. It involves cycles of intense chemo (discussed above). Many patients older than 60 are healthy enough to be treated in the same way, although sometimes the chemo may be less intense. People who are much older or are in poor health may not be able to take this intense treatment. In fact, intense chemo could actually shorten their lives.

In some cases, doctors may recommend less intense treatment. In some cases, this may induce remission. In others, it may control the leukemia for a time. Treatment of these patients is often not divided into induction and consolidation, but may be given every so often as long as it seems helpful.

Sometimes, these patients may be treated with drugs used to treat another disease called myelodysplastic syndrome. These drugs are not approved to treat AML, but still may be helpful. See our document Myelodysplastic Syndromes to find out more about these drugs.

Some patients decide against chemo and other drugs and instead choose supportive care. This focuses on treating any symptoms or problems that arise and keeping the person as comfortable as possible.

Maintenance

Maintenance involves giving a low dose of a chemo drug for months or years after consolidation is finished. This is often used for one type of AML (AML M3), but it is rarely used for other types.

Side effects of chemo

Chemo drugs work by killing cells that are dividing quickly, which is why they work against cancer cells. But other cells in the body, such as those in the bone marrow, the lining of the mouth and intestines, and the hair follicles, also divide quickly. These cells are likely to be affected by chemo, which can lead to side effects.

The side effects of chemo depend on the type and dose of drugs given and how long they are taken. These side effects may include:

• Hair loss
• Mouth sores
• Loss of appetite
• Nausea and vomiting
• Greater chance of infection (due to a shortage of normal white blood cells)
• Easy bruising or bleeding (due to a shortage of blood platelets)
• Tiredness (due to a shortage of red blood cells)

Most of these side effects go away after treatment ends. And there are often ways to manage these side effects during treatment. For example, there are drugs than can be taken along with the chemo to prevent or reduce nausea and vomiting. Drugs known as growth factors are sometimes given to keep blood counts higher and reduce the chance of infection. (But doctors aren't sure whether these growth factors affect the success of treatment.)

If your white blood cell counts are very low during treatment, you can help reduce your risk of infection by avoiding contact with germs. During this time, your doctor may tell you to:

• Wash your hands often.
• Don't eat fresh, uncooked fruits and vegetables and other foods that might carry germs.
• Don't be around fresh flowers and plants because they may carry mold.
• Make sure other people wash their hands before they come in contact with you.
• Stay away from large crowds and people who are sick (wearing a surgical mask can help protect you in these situations).

Antibiotics may be given before there are signs of infection or as soon as it looks like one may be starting.

If your platelet counts are low, you might get platelet transfusions to prevent bleeding. Low red blood cell counts, causing shortness of breath and tiredness, can be treated with drugs or with transfusions.

Tumor lysis syndrome is a side effect caused by the rapid breakdown of leukemia cells during treatment. It is most common during the first treatment (induction), when the patient has the highest numbers of leukemia cells. When these cells die, they break open and release their contents into the bloodstream. These "waste" chemicals can affect the kidneys, heart, and nervous system. Extra fluids or certain drugs that help rid the body of these substances can help prevent this problem.

Organs that could be damaged by chemo include the kidneys, liver, testes, ovaries, brain, heart, and lungs. By watching the patient carefully, the doctor may be able to prevent many of these side effects. If serious side effects happen, though, the drugs may have to be given at lower doses or even stopped. Be sure to tell your doctor about any problems you have.