Treatment for Acute Lymphocytic Leukemia (ALL)
Proper management of ALL focuses on control of bone marrow and systemic (whole-body) disease as well as prevention of cancer at other sites, particularly the central nervous system (CNS).
In general, ALL treatment is divided into several phases:
- Induction chemotherapy to bring about remission–that is, leukemic cells are no longer found in bone marrow samples. For adult ALL, standard induction plans include prednisone, vincristine, and an anthracycline drug; other drug plans may include L-asparaginase or cyclophosphamide. For children with low-risk ALL, standard therapy usually consists of three drugs (prednisone, L-asparaginase, and vincristine) for the first month of treatment. High-risk children may receive these drugs plus an anthracycline such as daunorubicin.
- Consolidation therapy (1-3 months in adults; 4-8 months in children) to eliminate any leukemia cells that are still "hiding" within the body. A combination of chemotherapeutic drugs is used to keep the remaining leukemia cells from developing resistance. Patients with low- to average-risk ALL receive therapy with antimetabolite drugs such as methotrexate and 6-mercaptopurine (6-MP). High-risk patients receive higher drug doses plus treatment with extra chemotherapeutic agents.
- CNS prophylaxis (preventive therapy) to stop the cancer from spreading to the brain and nervous system. Standard prophylaxis may consist of (1) cranial (head) irradiation plus spinal tap or intrathecal (IT; into the space around the spinal cord and brain) delivery of the drug methotrexate; (2) high-dose systemic and IT methotrexate, without cranial irradiation; or (3) IT chemotherapy. Only children with T-cell leukemia, a high white blood cell count, or leukemia cells in the cerebrospinal fluid (CSF) need to receive cranial irradiation as well as IT therapy.
- Maintenance treatments with chemotherapeutic drugs (e.g., prednisone + vincristine + cyclophosphamide + doxorubicin; methotrexate + 6-MP) to prevent disease recurrence once remission has been achieved. Maintenance therapy usually involves drug doses that are lower than those administered during the induction phase. In children, an intensive 6-month treatment program is needed after induction, followed by 2 years of maintenance chemotherapy.
Follow-up therapy for ALL patients usually consists of:
- supportive care, such as intravenous nutrition and treatment with oral antibiotics (e.g., ofloxacin, rifampin), especially in patients with prolonged granulocytopenia; that is, too few mature granulocytes (neutrophils), the bacteria-destroying white blood cells that contain small particles, or granules (< 100 granulocytes per cubic millimeter for 2 weeks); and
- transfusions with red blood cells and platelets.
A laboratory test known as polymerase chain reaction (PCR) is advisable for ALL patients, since it may help to identify specific genetic abnormalities. Such abnormalities have a large impact upon prognosis and, consequently, treatment plans. PCR testing is especially important for patients whose disease is B-cell in type. B-cell ALL usually is not cured by standard ALL therapy. Instead, higher response rates are achieved with the aggressive, cyclophosphamide-based regimens that are used for non-Hodgkin's lymphoma.
Among ALL patients, most children and more than 50% of adults are positive for the Philadelphia chromosome (Ph1). Because these patients have a worse prognosis than other individuals with ALL, many oncologists recommend allogeneic bone marrow transplantation (alloBMT), since remission may be brief following conventional ALL chemotherapy.
People who receive bone marrow transplantation will require protective isolation in the hospital, including filtered air, sterile food, and sterilization of the microorganisms in the gut, until their total white blood cell (WBC) count is above 500.
Recurrent ALL patients usually do not benefit from additional chemotherapy alone. If possible, they should receive re-induction chemotherapy, followed by allogeneic bone marrow transplant (alloBMT).
Alternatively, patients with recurrent ALL may benefit from participation in new clinical trials of alloBMT, immune system agents, and chemotherapeutic agents, or low-dose radiotherapy, if the cancer recurs throughout the body or CNS.