The main treatment for acute lymphocytic leukemia (ALL) in adults involves the long-term use of chemotherapy. In the past several years, doctors have begun to use more intensive chemotherapy regimens, which has led to more responses to treatment. But these regimens are also more likely to cause side effects, such as low white blood cell counts. Patients may need to take other drugs to help prevent or treat these side effects.
Treatment typically takes place in 3 phases:
- Induction (or remission induction)
- Consolidation (intensification)
- Maintenance
The total treatment usually takes about 2 years, with the maintenance phase taking up most of this time. Treatment may be more or less intense, depending on the subtype of ALL and other prognostic factors.
An important part of treatment of ALL is central nervous system (CNS) prophylaxis – treatment that is meant to ensure the leukemia does not spread to (or remain in) the brain or spinal cord. This is described in more detail below.
Induction
The goal of induction chemotherapy is to achieve a remission. This means that leukemia cells are no longer found in bone marrow samples, the normal marrow cells return, and the blood counts become normal. But a remission is not necessarily a cure, as leukemia cells may still be hiding somewhere in the body.
This is a phase of intensive chemotherapy that usually lasts for a month or so. Different combinations of chemo drugs may be used, but they typically include:
- Vincristine
- Dexamethasone or prednisone
- Doxorubicin (Adriamycin), daunorubicin, or a similar anthracycline drug
Based on the patient's prognostic factors, some regimens may also include cyclophosphamide, L-asparaginase, etoposide, and/or high doses of methotrexate or cytarabine (ara-C) as part of the induction phase.
For ALL patients whose leukemia cells have the Philadelphia chromosome, a targeted drug such as imatinib (Gleevec) is often included as well.
This first month of treatment is quite intensive and requires frequent visits to the doctor. You may spend some or much of this time in the hospital, because serious infections or other complications can occur. It is very important to take all medicines prescribed. Sometimes complications can be serious enough to be life-threatening, but with advances in supportive care (nursing care, nutrition, antibiotics, growth factors, red blood cell and platelet transfusions as needed, etc.) in recent years, these are much less common than in the past.
Most people are able to achieve a remission with induction chemotherapy. But because leukemia cells may still be hiding somewhere in the body, further treatment is needed.
CNS prophylaxis: Treatment to keep the leukemia cells from spreading to the CNS is often started at this time. This may include one or more of the following:
- Chemotherapy injected directly into the spinal fluid (called intrathecal chemotherapy). The drug used most often is methotrexate, but sometimes cytarabine or a steroid such as prednisone may be used as well.
- High-dose IV methotrexate or cytarabine
- Radiation therapy to the brain and spinal cord
Consolidation (intensification)
If the leukemia goes into remission, the next phase often consists of another fairly short course of chemotherapy, using many of the same drugs that were used for induction therapy. This typically lasts for a few months. Usually the drugs are given in high doses so that the treatment is still fairly intense. CNS prophylaxis may be continued at this time.
Some patients who go into remission are still at high risk for relapse, such as those who have certain subtypes of ALL or other poor prognostic factors. Doctors may suggest an allogeneic stem cell transplant (SCT) at this time, especially for those who have a brother or sister who would be a good donor match. An autologous SCT may be another option. The possible risks and benefits of stem cell transplants need to be weighed carefully, as it's still not clear how helpful they are. Patients considering this procedure may best be served by having it done in the context of a clinical trial at a center that has done a lot of stem cell transplants.
Maintenance
After consolidation, the patient is generally put on a maintenance chemotherapy program of methotrexate and 6-mercaptopurine (6-MP). In some cases, this may be combined with other drugs such as vincristine and prednisone. For ALL patients whose leukemia cells have the Philadelphia chromosome, the targeted drug imatinib is often included as well. Maintenance usually lasts for about 2 years. CNS prophylaxis may be continued at this time.
Some doctors feel that maintenance therapy may not be needed for some leukemias such as T-cell ALL and mature B-cell ALL (Burkitt leukemia).
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