Progress in the treatment of adolescents with acute lymphoblastic leukemia

BACKGROUND AND METHODS. The authors studied the clinical and biologic features and treatment response of 358 children with acute lymphoblastic leukemia (ALL), including 90 adolescents, treated on a single multiagent protocol (St. Jude Total Study XI, 1984-1988). This was done to clarify whether the disease differed in adolescents and to determine the degree of improvement in treatment outcome produced by this modern intense chemotherapy.

Compared with the younger children (1-9 years of age; infants 1 year old or younger excluded; n = 257), adolescents (10-18 years of age; n = 90) were significantly more likely to have adverse prognostic features, including T-cell phenotype, L2 blast cell morphologic characteristics, blasts with negative findings for common ALL antigen, and ploidy other than hyperdiploidy greater than 50. Eighty-six of the 90 (96%) adolescents achieved a complete remission, a rate similar to that of the children (97%). Although the event-free survival (EFS) of adolescents was shorter than that of younger children (5-year EFS of 66 +/- 8% versus 75 +/- 5%, respectively; P = 0.04), in this analysis of consecutively treated patients with ALL it showed a significant statistical and clinical improvement as compared with that in our previous study (St. Jude Total Study X, 1979-1983; 5-year EFS rate of 66 +/- 8% versus 37 +/- 5%, respectively; P < 0.001). Within the adolescent group treated on Total Study XI, the EFS was worse for those older than 15 years of age than for those 10-14 years old (46 +/- 15% versus 75 +/- 8%, respectively; P = 0.007). Toxic effects primarily included myelosuppression without severe sequelae. Approximately 96% of the therapy was administered in the outpatient setting.

The increased frequency of unfavorable clinical and biologic features undoubtedly accounts for the poorer prognosis of adolescents with ALL, a conclusion supported by the lack of independent prognostic importance of age in this study. The authors conclude that approximately two-thirds of adolescents can be cured when treated with this intensive but tolerable therapy, showing that this form of treatment significantly has changed the prognosis of adolescents with ALL.