If you achieve a complete remission following remission induction therapy, you will probably be advised to receive consolidation treatment. This will usually consist of:
- High-dose chemotherapy and an allogeneic stem cell transplant
- High-dose chemotherapy and an autologous stem cell transplant
- Conventional-dose chemotherapy delivered without stem cell support
The decision on which treatment to use is based on your feelings about the outcomes associated with each treatment. It is also based on the risk of your leukemia coming back based on cytogenetic results, your age, the availability of an HLA-matched sibling stem cell donor, your physician's opinion concerning the appropriateness of each treatment option, and the availability of each treatment in your area.
Whichever choice you make, it is important to try to find a marrow or stem cell donor as soon as possible following the initial diagnosis of AML. This allows for an immediate transplant if remission induction fails. It also gives you a wider range of options once remission is achieved.
Each treatment option carries some risks. Studies show that about 50 percent of patients who have transplants survive for at least 4 years, compared to 30 percent who have only chemotherapy. However, there is a higher risk of death due to the allogeneic transplant procedure than from autologous transplant or chemotherapy alone.
Patients who achieve a complete disappearance of visible cancer receive consolidation therapy with one or more courses of chemotherapy. Sometimes, only one consolidation course is given. However, this lower intensity consolidation treatment results in lower cure rates.
In general, patients with a translocation of chromosome 8 to chromosome 21 [t(8;21)] or chromosome 16 inversion have a better outcome than other patients with AML. The cure rate is about 50 percent. These patients need several (three to four) courses of high doses of Cytosar® (cytarabine) to achieve these results. For these patients, a reduction in the amount of consolidation therapy can unnecessarily reduce the chance for cure.
Risks and Benefits of an Allogeneic Stem Cell Transplant
If you have an allogeneic stem cell transplant as consolidation, you can have the transplant immediately after remission induction. There does not appear to be an advantage to receiving more chemotherapy before the transplant. Additional chemotherapy before the allogeneic transplant may increase toxicity without preventing relapses.
You should consider an allogeneic transplant as consolidation if you have risk factors for recurrence. These include:
- Adverse cytogenetic abnormalities
- More than one induction cycle needed to achieve a remission
- You do not wish to undergo the three to four cycles of consolidation and maintenance required for adequate control of disease with conventional chemotherapy alone
Some patients with a suitable stem cell donor may consider delaying allogeneic transplant until first relapse. These include patients:
- Over the age of 50 to 60. This depends, however, on other risk factors and the patient's general health.
- With acute promyelocytic leukemia (a condition which involves an excess of immature cells and a lack of mature ones). The cure rate in this disease with ATRA and chemotherapy or Trisenox® (arsenic trioxide) is 70 percent to 80 percent.
- With "good" cytogenetic abnormalities [t(8;21) and inversion 16], who can tolerate all prescribed consolidation therapy.
If you choose to have a stem cell transplant only if you relapse, it is important that it be performed at the very first sign of relapse. This requires bone marrow examinations every 3 to 6 months for the first 2 years after diagnosis. This strategy offers the best chance to catch the leukemia early, when treatment will be more effective.
Consolidation chemotherapy typically consists of three to four cycles of the drug cytarabine given in high doses over 5 days. Cytarabine is given together with additional chemotherapy drugs, such as VePesid®, Toposar®, or Etopophos® (etoposide); Cerubidine® (daunomycin), or Idamycin® (idarubicin). Remission duration is related to the dose and the number of cycles of cytarabine is given. In general, the more intensive the consolidation, the higher the cure rate.
The administration of consolidation chemotherapy interferes with the production of blood cells by the bone marrow. This results in low white blood cell counts. This is called myelosuppression.
There is usually a delay of 1 to 2 weeks after the administration of chemotherapy before the bone marrow resumes function. During this time, you will have low blood counts. Because of this, you may be given antibiotics and observed for infections. Neupogen® (filgrastim) is a growth factor that hastens the recovery of white blood cells after the administration of chemotherapy.
Consolidation chemotherapy usually causes myelosuppression for 14 to 21 days for each of three to four courses. If you are unwilling or unable to undergo intensive consolidation chemotherapy, you may wish to consider either an autologous or allogeneic transplant. The amount of therapy required for these procedures is shorter. They also produce results that are equivalent or superior to the best chemotherapy regimens.
The average age at the time of diagnosis for patients with AML is 65 years. This is 10 to 15 years older than the average age of patients who take part in clinical trials of AML treatments. In general, only about one-third of patients older than 60 tolerate the intensive chemotherapy required to achieve the best results.
However, it is probably the higher frequency of other organ problems in older people and not age that leads to increased toxicity. Older patients with AML also frequently have a leukemia that comes from more primitive myeloid cells. This makes the disease more difficult to eradicate because there are no normal cells left to refill the bone marrow.
Patients over 60 with AML and no other major medical problem appear to benefit from intensive consolidation treatment. Filgrastim is a white blood cell growth factor currently approved by the U.S. Food and Drug Administration to help white blood cell production. It may be particularly beneficial to older patients.
Most older patients cannot tolerate intensive chemotherapy. They are often offered supportive care, hospice care, or lower intensity therapy such as low-dose cytarabine. There are now many investigational drugs being tested specifically in older patients with good results. These include clofarabine, cloretazine, DacogenTM (decitabine), tipifarnib, and many other "targeted therapies."
If you are over the age of 60 and have AML, make sure to ask your doctor about these other alternative options, particularly if your doctor feels that intensive chemotherapy may be too toxic for you or if they offer only supportive care or hospice care. You may need to be referred to a specialized leukemia center for these treatments or they may be available through research programs in which your oncologist participates.
Research is in progress to refine existing treatments and to develop new ones. For information on some of the techniques currently under investigation, see Strategies to Improve Treatment.
This content was last reviewed
August 15, 2010 by Dr. Reshma L. Mahtani.