Treatment of AML is usually divided into 2 chemotherapy phases:

• remission induction
• consolidation (post-remission therapy)

In some cases, people with AML may have very high numbers of leukemia cells in their blood when they are diagnosed, which can cause problems with normal circulation. Chemotherapy may not lower the number of cells until a few days after the first dose. In the meantime, leukapheresis may be used before chemotherapy. For this procedure, a needle is placed into a vein in the arm. The patient's blood is passed through a special machine that removes white blood cells (including leukemia cells) and returns the rest of the blood cells and plasma to the patient. This treatment lowers blood counts right away. The effect is only for a short time, but it may help until the chemotherapy has a chance to work.

Remission induction

This first part of treatment is aimed at getting rid of all visible leukemia. In younger patients, it usually involves treatment with 2 chemotherapy drugs, cytarabine (ara-C) and an anthracycline drug such as daunorubicin (daunomycin) or idarubicin. Sometimes a third drug, 6-thioguanine, is added. This intensive therapy, which usually takes place in the hospital, typically lasts about a week.

How intense the treatment is may depend on a person's age and on other prognostic factors. Doctors often give more intensive chemotherapy to people under the age of 60. Some older patients in good health may benefit from similar or slightly less intensive treatment. People who are much older or are in poor health may not tolerate chemotherapy well. In some cases, doctors may recommend low-intensity chemotherapy with a single drug. Or they may advise supportive care, which focuses on treating any symptoms or complications that arise and keeping the person as comfortable as possible.

Age, health, and other factors clearly need to be taken into account when considering treatment options. Doctors are also trying to determine whether people with certain gene or chromosome changes are more likely to benefit from more intensive treatment.

In rare cases where the leukemia has spread to the brain or spinal cord, chemotherapy may be given into the cerebrospinal fluid (CSF) as well.

Most of the normal bone marrow cells as well as the leukemia cells will be destroyed by the treatment. During chemotherapy and the following couple of weeks, the patient's blood cell counts will probably be dangerously low, and drugs to raise white blood cell counts, antibiotics, and blood product transfusions may be used to help protect against complications. Usually, the patient stays in the hospital during this time.

If induction is successful, no leukemia cells will be found in the blood, and the number of blast cells in the bone marrow will be less than 5% within a week or two. Normal bone marrow cells will return in a couple of weeks and start making new blood cells.

If one week of treatment does not induce remission, the process may be repeated.

Induction is successful in about 40% to 80% of all AML patients. This depends to a large part on a person's specific prognostic factors. For instance, older people are more likely to have unfavorable cytogenetic test results, are more likely to have a pre-existing blood disorder, and are less likely to be able to tolerate intensive therapy than younger patients, so generally their disease don't respond as well to treatment.

Remission induction usually does not destroy all the leukemia cells, and a small number often persist. Without more treatment, called consolidation, the leukemia is likely to return within several months.

Consolidation (post-remission therapy)

If remission induction is successful, further treatment may be given to try to destroy any remaining leukemia cells and help prevent a relapse.

For younger patients, the main options for AML consolidation therapy are:

• several cycles of high-dose cytarabine (ara-C) chemotherapy
• allogeneic (donor) stem cell transplant
• autologous stem cell transplant

High-dose consolidation chemotherapy differs from induction therapy in that usually only cytarabine (ara-C) is used. The drug is given at very high doses, typically over 5 days. This is repeated about every 4 weeks, usually for a total of 3 or 4 cycles. Four years after this treatment, about 40% of patients younger than 60 years old will not show any signs of leukemia. But this number is affected by certain prognostic factors, such as whether the leukemia cells have certain gene or chromosome changes.

Another approach after successful induction therapy is a stem cell transplant. Patients first receive very high doses of chemotherapy to destroy all bone marrow cells. This is followed by either an allogeneic (from a donor) or autologous (patient's own) stem cell transplant to restore blood cell production. Stem cell transplants have been found to reduce the risk of leukemia coming back more than standard chemotherapy, but they are also more likely to have serious complications, including an increased risk of death from treatment.

Older patients or those in poor health may not be able to tolerate such intensive consolidation treatment. Common treatment options include:

• 1 or 2 cycles of higher dose ara-C (usually not quite as high as in younger patients)
• 1 or 2 cycles of standard dose ara-C, possibly along with idarubicin or daunorubicin
• non-myeloablative stem cell transplant (mini-transplant)

Older patients generally don't do as well as those younger than 60. Unfortunately, studies have found that giving them more intensive therapy raises the risk of serious side effects (including treatment-related death) without providing much more of a benefit. In general, around 15% to 20% of older patients are still free of leukemia several years after treatment.

It is not always clear which of the treatment options is best for consolidation. They each have their pros and cons. Doctors look at several different factors when recommending what type of post-remission therapy a patient should receive. These include:

• How many courses (cycles) of chemotherapy it took to bring about a remission. If it took more than one course, some doctors recommend that the patient receive a more intensive program, which might involve a stem cell transplant.

• The availability of a brother, sister, or an unrelated donor who matches the patient's tissue type. If a close enough tissue match is found, an allogeneic (donor) stem cell transplant may be an option, especially for younger patients.

• The potential of collecting leukemia-free bone marrow cells from the patient. If lab tests show that a patient is in remission, collecting stem cells from the patient's bone marrow or blood for an autologous stem cell transplant may be an option. Stem cells collected from the patient would be purged (treated in the lab to try to remove or kill any remaining leukemia cells) to lower the chances of relapse.

• The presence of one or more adverse prognostic factors, such as certain chromosome changes, a very high initial white blood cell count, AML that develops from a myelodysplastic syndrome or after treatment for an earlier cancer, or spread to the central nervous system. These factors might lead doctors to recommend more aggressive therapy, such as a stem cell transplant. On the other hand, for people with good prognostic factors, such as favorable chromosome changes, many doctors might advise holding off on a stem cell transplant unless the disease recurs.

• The age of the patient. Older patients may not be able to tolerate some of the severe side effects that can occur with high-dose chemotherapy or stem cell transplants.

• The patient's wishes. There are many issues that revolve around quality of life that must be discussed. An important issue is the higher chance of early death from high-dose chemotherapy or a stem cell transplant. This and other issues must be discussed between the patient and the doctor.

Stem cell transplants are intensive treatments with real risks of serious complications, including death, and their exact role in treating AML is not clear. Some doctors feel that if the patient is healthy enough to withstand the procedure and a compatible donor is available, an allogeneic transplant offers the best chance for long-term survival. Others feel that studies have not yet shown this conclusively, and that in some cases a transplant should be reserved in case the leukemia comes back after standard treatment. Because most studies of stem cell transplants have involved patients who tend to be younger and in better health, their improved survival might not be due to the procedure. That is, it may be that they would have done just as well with standard high-dose chemotherapy. Research in this area continues.

Last Medical Review: 08/06/2009
Last Revised: 08/06/2009