Prognostic (Risk) Groups

For decades, clinical trial groups studying childhood ALL have used risk classification schemes to assign patients to therapeutic regimens on the basis of their estimated risk of treatment failure. Initial risk classification systems used clinical factors such as age and presenting WBC count. Response-to-therapy measures were subsequently added, with some groups using early morphological bone marrow response (e.g., at day 8 or day 15) and with other groups using response of circulating leukemia cells to single-agent prednisone. Contemporary risk classification systems continue to use clinical factors such as age and presenting WBC count and incorporate cytogenetics and genomic lesions of leukemia cells at diagnosis (e.g., favorable and unfavorable translocations) and response to therapy based on detection of MRD at EOI (and in some cases at later time points).[141] The risk classification systems of the COG and the BFM groups are briefly described below.