General Information
Note: Estimated new cases and deaths from acute lymphoblastic leukemia (ALL; also called acute lymphocytic leukemia) in the United States in 2009: [1]
- New cases: 5,760.
- Deaths: 1,400.
Sixty percent to 80% of adults with ALL can be expected to attain complete remission status following appropriate induction therapy. Approximately 35% to 40% of adults with ALL can be expected to survive 2 years with aggressive induction combination chemotherapy and effective supportive care during induction therapy (appropriate early treatment of infection, hyperuricemia, and bleeding). A few studies, including a Cancer and Leukemia Group B study (CLB-8811), that use intensive multiagent approaches suggest that a 50% 3-year survival is achievable in selected patients, but these results must be verified by other investigators.[2,3,4,5]
As in childhood ALL, adult patients with ALL are at risk of developing central nervous system (CNS) involvement during the course of their disease. This is particularly true for patients with L3 histology.[6] Both treatment and prognosis are influenced by this complication. The examination of bone marrow aspirates and/or biopsy specimens should be done by an experienced oncologist, hematologist, hematopathologist, or general pathologist who is capable of interpreting conventional and specially stained specimens. Diagnostic confusion with acute myelocytic leukemia (AML), hairy-cell leukemia, and malignant lymphoma is not uncommon. Proper diagnosis is crucial because of the difference in prognosis and treatment of ALL and AML. Immunophenotypic analysis is essential because leukemias that do not express myeloperoxidase include M0 and M7 AML as well as ALL.
Appropriate initial treatment, usually consisting of a regimen that includes the combination of vincristine, prednisone, and anthracycline, with or without asparaginase, results in a complete remission rate of up to 80%. Median remission duration for the complete responders is approximately 15 months. Entry into a clinical trial is highly desirable to assure adequate patient treatment and also maximal information retrieval from the treatment of this highly responsive, but usually fatal, disease. Patients who experience a relapse after remission can be expected to succumb within 1 year, even if a second complete remission is achieved. If there are appropriate available donors and if the patient is younger than 55 years of age, bone marrow transplantation may be a consideration in the management of this disease.[7] Transplant centers performing five or fewer transplants annually usually have poorer results than larger centers.[8] If allogeneic transplant is considered, transfusions with blood products from a potential donor should be avoided if possible.[5,9,10,11,12,13,14]
Patients with L3 morphology have improved outcomes, as evidenced in a Cancer and Leukemia Group B study (CLB-9251), when treated according to specific treatment algorithms.[15,16] Age, which is a significant factor in childhood ALL and in AML, may also be an important prognostic factor in adult ALL. In one study, overall the prognosis was better in patients younger than 25 years; another study found a better prognosis in those younger than 35 years. These findings may, in part, be related to the increased incidence of the Philadelphia chromosome (Ph1) in older ALL patients, a subgroup associated with poor prognosis.[2,3] Elevated B2-microglobulin is associated with a poor prognosis in adults as evidenced by lower response rate, increased incidence of CNS involvement, and significantly worse survival.[17] Patients with Ph1-positive ALL are rarely cured with chemotherapy. Many patients who have molecular evidence of the bcr-abl fusion gene, which characterizes the Ph1 , have no evidence of the abnormal chromosome by cytogenetics. Because many patients have a different fusion protein from the one found in chronic myelogenous leukemia (p190 vs. p210), the bcr-abl fusion gene may be detectable only by pulsed-field gel electrophoresis or reverse-transcriptase polymerase chain reaction (RT-PCR). These tests should be performed whenever possible in patients with ALL, especially those with B-cell lineage disease. Two other chromosomal abnormalities with poor prognoses are t(4;11), which is characterized by rearrangements of the MLL gene and may be rearranged despite normal cytogenetics, and t(9;22). In addition to t(9;22) and t(4;11), patients with deletion of chromosome 7 or trisomy 8 have been reported to have a lower probability of survival at 5 years compared to patients with a normal karyotype.[18] L3 ALL is associated with a variety of translocations that involve translocation of the c-myc proto-oncogene to the immunoglobulin gene locus: t(2;8), t(8;12), and t(8;22).
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