The treatment of acute childhood leukemia: predictions for the future based on extrapolations from the past

Acute lymphoblastic leukemia in children: current status, controversies, and future perspective

Disease-free survival (DFS) in childhood ALL is 60%, and survival in good, average, and poor prognostic groups defined by initial WBC and age is 90, 60, and 45%, respectively. Additional immunological, morphological, biochemical, cytokinetic, and cytogenetic factors have been identified, illustrating the heterogeneity of ALL and its derivation from malignant clones at various stages of differentiation and with varying rates of proliferation. Of biologic importance, these factors may refine further the characteristic features of clinically-determined prognostic groups. Multivariate analysis of large prospective trials with homogeneous therapy will be required to determine the independent prognostic importance of these factors. Current treatment strategies in ALL include (1) tailoring therapy and its intensity to prognostic groups; (2) multiple-drug combinations in induction; (3) early use of intrathecal (IT) methotrexate (MTX); (4) CNS prophylaxis with IT MTX alone in good prognosis patients and combined cranial radiation (CXRT), 1800 rads plus IT MTX, in average and poor prognosis patients. Current studies show a CNS relapse rate of 5% in all prognostic groups. Late neuropsychological defects caused by cranial XRT and IT MTX have prompted programs designed to reduce the potential late toxicity of CNS prophylaxis. More pronounced in younger children, these abnormalities include decreased IQ, visual-motor incoordination, poor performance in mathematics, and memory dysfunction. Until 1980, more intensive induction, consolidation, and maintenance therapy had failed to prolong DFS in children with a poor prognosis. In West Germany (Berlin-Frankfurt-Muenster protocol) a 70 to 75% DFS is seen in all patients regardless of initial WBC, suggesting that effective therapy will override prognostic factors. Ultra-high-dose MTX, without cranial radiation, is also showing promise in poor prognosis patients. Other issues include the optimal duration of therapy, the role of testicular biopsies, and prophylactic testicular radiation. Recent studies suggest that prognostic factors lose their significance after 2 years of continuous complete remission and that 2 years of maintenance therapy is adequate. Bilateral open-wedge testicular biopsies have identified occult testicular disease in 8 to 10% of males. A unified approach to children with leukemia/lymphoma, a group with a particularly poor prognosis, utilizing NHL-type therapy may be more effective than conventional ALL therapy.(ABSTRACT TRUNCATED AT 400 WORDS)

Progress in the treatment of childhood acute leukemia: a review

The dramatic improvements in the survival experience for children diagnosed with acute leukemia are analyzed using data collected through hospitals participating in the National Cancer Institute's End Results Group Program between 1950 and 1973. Children under 15 years of age who were diagnosed with both acute lymphocytic leukemia (ALL) and acute nonlymphocytic leukemia (ANLL) showed moderate improvements in the 1950s, but beginning in the 1960s those with ALL did far better. Statistically significant differences at the 0.05 level were noted between their three-year survival rates for all cohorts analyzed between 1960 and 1973. For the 1970-1973 cohort, three-year survival rates were 49% and 20% for ALL and ANLL, respectively, and five-year survival rates were 34% and 12%. Between 1950 and 1976 the age-adjusted incidence rate for all childhood leukemias remained relatively stable in a sample of five geographic areas, changing from 4.6 per 100,000 children under 15 years of age to 4.3 per 100,000. In contrast, the corresponding age-adjusted mortality rate fell approximately 45% over the same period, from 4.4 per 100,000 to 2.4 per 100,000.

Childhood leukemia and lymphoma: correlation of clinical features with immunological and morphological studies

Malignant cells from 49 children with lymphoid neoplasms other than Hodgkin disease were evaluated by surface marker and morphologic studies. We classified the patients into three groups: 36 patients (74%) with acute lymphocytic leukemia; 7 (14%) classified as convoluted lymphocytic lymphoma/leukemia; and 6 (12%) with small noncleaved follicular center cell lymphoma/leukemia. Diffuse marrow involvement was present at diagnosis in some patients in the latter two groups, but their clinical course was not characteristic of the patients with acute lymphocytic leukemia. Male predominance, poor prognosis, and high incidence of central nervous system disease characterized patients in the convoluted lymphocytic and follicular center cell lymphoma/leukemia groups. Clinical presentation in these two groups differed. Proliferations of convoluted lymphocytes were associated with mediastinal masses and proliferations of follicular center cells with intraabdominal tumors. The high incidence of CNS disease in children with neoplasms of convoluted lymphocytes and follicular center cells suggests that these processes have a predilection for the CNS and that patients with them may benefit from CNS prophylaxis.

Long-term survival in acute leukemia in Argentina: a study of 78 cases

A total of 78 patients with acute leukemia [69 acute lymphoblastic leukemia (ALL) and 9 acute myeloblastic leukemia (AML)] survived more than 4 years. In the years between 1958 and 1967 the number of patients with ALL in Argentina who survived 4 years was 1%. This increased to 21% in the years between 1967 and 1972. The major cause of this increase was the initiation in 1967 of protocols of therapy on a national scale through a cooperative group known as GATLA. In AML patients the number of long-term survivals remained unchanged during both periods. A large percent of the long-term survivors had lower WBC, a higher platelet count, and no hepato- or splenomegaly, lymphadenopathy, or hemorrhagic manifestations at diagnosis. However, only for those patients with a WBC under 100,000/mm3 at diagnosis was there a significant prognostic implication (p less than 0.01). Patients with acute lymphoblastic leukemia who survive more than 4 years without relapse have about an 80% chance of long survival. For those who have lived 4 years with one or more lapses, there is only a 17% chance of long survival, and of these only those who develop extramedullar relapse (CNS or testicular) without bone marrow involvement have a chance of long survival. Patients who live 4 years in continuous complete remission have the same chance of very long survival regardless of previous therapy.

The definitive treatment of children with acute leukemia

Current therapy has resulted in improved prognosis in previously untreated children with acute lymphocytic leukemia less than 16 years of age. The induction phase of chemotherapy should include the use of at least prednisone and vincristine. This combination should result in a hematologic remission in about 90 per cent of the patients. The efficacy of the addition of either L-asparaginase or daunomycin, the consolidation phase or the periodic readministration of induction drugs has not been established. Specific central nervous system treatment, early in the course of therapy, is an integral component of recently reported effective protocols. Several modalities of prophalytic central nervous system therapy have been utilized. These include cranial irradiation plus intrathecal methotrexate, craniospinal irradiation and intrathecal methotrexate alone. An encephalopathy syndrome has been reported as a complication in 10 to 66 per cent of these patients. The most effective form of central nervous system therapy, associated with the least toxicity, has not been established. Maintenance chemotherapy should include a combination of two or more drugs. Complications are numerous, and include hematopoietic depression, immunosuppression, overwhelming infections, and, possibly, the development of secondary primary cancers. In the most successful protocols maintenance chemotherapy has been administered for 3 years. Because of the potential significant toxicity there is a need to define the optimal duration of maintenance therapy. Psychological complications developing in a patient with a disease now considered a potential long term chronic illness, rather than a disease once considered universally fatal, are also discussed. The possibility of an immunologic deficiency allowing for the initial development of acute lymphocytic leukemia and the role of immunotherapy are presented. While the use of intensive combination chemotherapy and specific central nervous system prophylactic therapy have resulted in an improved prognosis in childhood acute lymphocytic leukemia, because of a significant incidence of failures, a standardized single form of therapy has not been established.