Acute Lymphocytic Leukemia (ALL)

Physicians devise a course of treatment for each ALL patient that takes a number of factors into consideration: the ALL subtype; whether the patient has been treated already, with what, and how successfully; the number of leukemic cells detectable in the blood; which chromosomal alterations are present; and the patient's age and overall health. For this reason, ALL patients with the same disease subtype may receive different treatments.

The standard treatment approaches for adult leukemia are chemotherapy, immunotherapy, and bone marrow transplantation. Radiation therapy -- treatment with high-energy rays that destroy cancer cells -- is sometimes used for leukemia in the central nervous system or testicles and for pain caused by bone destruction. But because leukemia is systemic, surgery is almost always ineffective.

Treatment for ALL is typically divided into three phases:

• Remission Induction
• Remission Continuation (consolidation, intensification),
• Maintenance

Remission Induction

The goal of the remission induction phase is to induce a remission, a state in which there is no visible evidence of disease and blood counts are normal. Patients may receive a combination of drugs during this phase including vincristine, prednisone, L-asparaginase, doxorubicin, daunorubicin, or cyclophosphamide. Treatment can last up to four weeks, and patients may need to be hospitalized during remission induction therapy.

Remission Continuation (Consolidation, Intensification)

In the second phase, the continuation, consolidation, or intensification phase, patients may receive high doses of chemotherapy, which are designed to eliminate any remaining leukemic cells. During this phase, treatment may include a combination of two or more of the agents 6-mercaptopurine, methotrexate, vincristine, prednisone, cytarabine, doxorubicin, daunorubicin, mitoxantrone, etoposide, ifosfamide, and cyclophosphamide.

Maintenance

During the third phase, the maintenance phase, patients may receive lower doses of drugs but for long periods of time -- up to two years. The goal of this phase is to destroy any stray leukemia cells that have evaded the agents used in the remission induction and consolidation stages; these cells may not be detectable by laboratory tests. Commonly used drugs for maintenance include methotrexate, 6-mercaptopurine, vincristine, and prednisone.

Immunotherapy

Physicians may include immunotherapeutic drugs throughout the course of treatment. These agents are designed stimulate the patient's own immune system to recognize and attack the leukemic cells. Immunotherapy agents include interferon alpha, which occurs naturally in the body, and monoclonal antibodies, which are genetically engineered proteins designed to target specific sites (antigens) on the surface of tumor cells. Monoclonal antibodies may be able to destroy diseased cells directly, or they may be used in a "conjugated" form, with radioisotopes (radioactive substances that radiate tumor cells), drugs, or toxins designed to destroy tumor cells attached to it.

Chemotherapy

It is not uncommon for ALL to spread to the central nervous system (CNS) -- the brain and the spinal cord. This occurs more frequently among patients who have the ALL subtype L3. Treatment to prevent or control CNS involvement is included in most patients' treatment regimen. To prevent spread of the disease to the CNS, physicians may administer chemotherapy intrathecally -- directly through the spinal column into the fluid that bathes the spinal cord and brain. Alternatively, patients may receive high-dose systemic chemotherapy or cranial irradiation -- radiation therapy to the head -- to prevent the spread of disease to the CNS.

Bone Marrow Transplant

A stem cell or bone marrow transplant is an option for some ALL patients; this procedure is done after an initial remission is achieved. In this procedure, bone marrow or stem cells -- blood-forming cells -- are filtered from the patient's (autologous transplantation) or a donor's (allogeneic transplantation) marrow or bloodstream and then frozen. The patient then receives a high dose of chemotherapy or radiotherapy, which destroys tumor cells but also damages the stem cells in the patient's bone marrow. The harvested stem cells or marrow are then administered, or transplanted, to help rebuild the patient's immune system.

New, highly sensitive laboratory tests can now probe for minimal residual disease -- the very few leukemia cells that may remain in the body after treatment ends -- in patients with certain specific types of leukemia. With the information derived from such tests, physicians can chart out further treatment options for leukemia patients.