Use of Clinical and Laboratory Features to Define Prognostic Subgroups in B-Precursor Acute Lymphoblastic Leukemia: Experience of the Pediatric Oncology Group

Abstract

For more than a decade, the Pediatric Oncology Group (POG) has been engaged in a series of studies of acute lymphocytic leukemia in childhood in which advances in therapeutic approaches have been undertaken in conjunction with biologic studies of the properties of leukemic cells. Historically, the POG has assigned children to treatment arms on the basis of clinical and laboratory measurements at the time of diagnosis (Pullen et al. 1983, 1984). In early studies, attention was focused on the immunophenotypic differences among leukemia’s, and specific treatments were derived for patients with T-cell ALL (T-ALL), B-precursor ALL, and B-cell ALL (B- ALL) (Pullen et al. 1982, 1983; Sullivan et al. 1990). Patients with T-ALL, originally defined by serologic studies first with heteroantisera and later with monoclonal antibodies (Borowitz et al. 1985), have been treated as poor prognosis leukemia irrespective of clinical risk factors. In addition, the small number of patients with surface Ig-positive (sIg⁺) B-ALL have been treated in a manner similar to patients with Burkitt’s lymphoma (Sullivan et al. 1990). Patients with B-precursor ALL have been assigned to treatment groups on the basis of clinical criteria, including age at diagnosis, leukocyte count, and adenopathy and organomegaly (Pullen et al. 1984; Crist et al. 1990).