Acute Lymphocytic Leukemia Health Article

ALL in remission

ADULTS.

Remission is achieved in many people within days of beginning treatment. Treatment does not end at that point, but rather enters into the next phases, called consolidation and maintenance. Several different approaches can be used in these. Some patients receive long-term chemotherapy with drugs that might include cytarabine, cyclophosphamide, methotrexate, 6-mer-captopurine, vincristine, prednisone, or doxorubicin. Other patients undergo high-dose chemotherapy or combination chemotherapy and radiation therapy to ablate or wipe out their own bone marrow, and then have bone marrow or stem cell transplants. Adverse effects of bone marrow transplant include significant risk of serious infection and graft versus host disease (GVHD), in which the transplanted cells fail to "recognize" the host's cells as self and attack the host cells. Medications to decrease this risk include those that suppress the immune system and steroids.

Central nervous system prophylaxis, as either intrathecal chemotherapy or radiation therapy or both, typically continues through at least a portion of the post-remission therapy.

Adults who receive intensive chemotherapy have a 40% likelihood of long-term survival.

CHILDREN.

In children, remission induction therapy is followed by a phase termed consolidation or intensification, and then by a phase termed maintenance. During intensification, children receive intermediate or high-dose methotrexate, plus some of the same drugs that are used in induction, new drugs that do not cross-react with those used in induction, high-dose asparaginase, or some combination of these.

The maintenance phase of treatment for children with ALL continues for 18 to 30 months. Daily oral mercaptopurine and weekly oral or injected methotrexate are given on an outpatient basis, with frequent blood tests and examinations. Some protocols add pulses of vincristine and prednisone during the maintenance phase.

Recurrent ALL

ADULTS.

Adults who relapse after initial remission and maintenance therapy often undergo reinduction chemotherapy and are then referred for bone marrow or stem cell transplant. Some receive transplants of umbilical cord blood. Such transplants carry the risk of graft versus host disease, but also carry the possibility of graft versus leukemia, in which the transplanted cells attack the residual leukemic cells. Unlike graft-versus-host disease, graft versus leukemia is useful.

New treatments for relapsed ALL include immunotherapies or biological response modifiers. Some reduce adverse effects of treatment and others are used to fight the leukemia. Some of these include cytokines, substances that stimulate the production of blood cells after treatment has suppressed the bone marrow, and colony-stimulating factors, which have the same effect. Other immunotherapies, such as monoclonal antibodies and interferon, have not yet been shown effective against ALL, but are still under study.

CHILDREN.

The treatment and prognosis of children who relapse depends on the timing of that relapse. Relapse that occurs within six months is often treated with bone marrow transplantation. Early relapse carries the least favorable prognosis, with only 10% to 20% chance of long-term survival. Relapse that occurs more than a year after initial treatment is finished can be treated with another full round of chemotherapy, and bone marrow transplant reserved for those children who relapse a second time. Those with such late relapses have a 30% to 40% chance of long-term survival.

Recurrent disease may occur in a sanctuary site, or a part of the body difficult to penetrate with chemotherapeutic drugs. The central nervous system is the most common site of such recurrences. Children who have an isolated central nervous system relapse during the first 18 months of treatment have a 45% likelihood of long-term survival. Children with central nervous system relapse after the first 18 months of treatment have up to an 80% chance of long-term survival. Treatment for relapse in the central nervous system includes intrathecal chemotherapy, and for most children, the use of radiation therapy to the brain and spinal cord.

The testicles are the second most common site of relapse. Early testicular relapse (within the first 18 months of treatment) carries a 40% chance of long-term survival, and late testicular relapse carries an 85% chance of long-term survival. Another sanctuary site is the eye, but isolated relapse here is unusual.