To define more uniform criteria for risk-based treatment assignment for children with acute lymphoblastic leukemia (ALL), the Cancer Therapy Evaluation Program (CTEP) of the National Cancer Institute (NCI) sponsored a workshop in September 1993. Participants included representatives from the Childrens Cancer Group (CCG), Pediatric Oncology Group (POG), Dana-Farber Cancer Institute (DFCI), St Jude Children's Research Hospital (SJCRH), and the CTEP.

Workshop participants presented and reviewed data from ALL clinical trials, using weighted averages to combine outcome data from different groups.

For patients with B-precursor (ie, non-T, non-B) ALL, the standard-risk category (4-year event-free survival [EFS] rate, approximately 80%) will include patients 1 to 9 years of age with a WBC count at diagnosis less than 50,000/microL. The remaining patients will be classified as having high-risk ALL (4-year EFS rate, approximately 65%). For patients with T-cell ALL, different treatment strategies have yielded different conclusions concerning the prognostic significance of T-cell immunophenotype. Therefore, some groups/institutions will classify patients with T-cell ALL as high risk, while others will assign risk for patients with T-cell ALL based on the uniform age/WBC count criteria. Workshop participants agreed that the risk category of a patient may be modified by prognostic factors in addition to age and WBC count criteria, and that a common set of prognostic factors should be uniformly obtained, including DNA index (DI), cytogenetics, early response to treatment (eg, day-14 bone marrow), immunophenotype, and CNS status.

The more uniform approach to risk-based treatment assignment and to collection of specific prognostic factors should increase the efficiency of future ALL clinical research.