Early and delayed consolidation chemotherapy significantly improves the outcome of children with intermediate risk acute lymphoblastic leukemia. Final results of the prospective randomized PETHEMA ALL-89 TRIAL.

BACKGROUND AND OBJECTIVES

To evaluate the impact of early and delayed consolidation chemotherapy on the outcome of children with acute lymphoblastic leukemia (ALL) stratified according to risk groups.

DESIGN AND METHODS

From 1989 to 1994, 195 children (< or = 15 years old) diagnosed as having ALL (ALL-L3 excluded) in 15 Spanish hospitals entered the prospective, randomized PETHEMA ALL-89 trial. Patients were stratified into low-risk (LR), intermediate-risk (IR) and high-risk (HR) groups according to their initial features and the rate of response to induction therapy. LR-ALL patients were randomized to receive or not early consolidation chemotherapy (C-1). After receiving C-1, IR patients were randomized to receive or not delayed consolidation chemotherapy (C-2). HR patients received C-1 and C-2 chemotherapy. Standard maintenance chemotherapy was administered to all patients for 2 years. High doses of intravenous methotrexate and 12 triple intrathecal doses were given as prophylaxis against central nervous system (CNS) disease.

RESULTS

The mean (and standard deviation) age was 6 (4) years and 120 patients were males. Fourteen patients had early pre-B-ALL, 149 common or pre-B-ALL, and 32 T-ALL. Complete remission (CR) was attained in 189 patients (97%), 11 of whom (6%) had a slow response. Risk group stratification after CR was: LR 89, IR 50 and HR 56 patients (including a subset of 26 patients at very high risk). Ten-year event-free survival (EFS) and overall survival (OS) probabilities for the whole series were 58% (95% CI: 52-64%) and 69% (61-77), respectively, with a median follow-up of 8.7 years. Dividing the patients according to risk group, the 10-year EFS and OS probabilities in the LR group were 71% (63-79) and 86% (80-92), respectively; in the IR group 69% (57-81) and 76% (64-88), respectively, and in the HR group 30% (18-42) and 44% (32-57), respectively. For LR patients receiving C-1, EFS and OS were 79% (57-92) and 90% (82-98), respectively, versus 62% (48-76) and 66% (51-81) in patients not receiving C-1 (p= 0.06). For IR patients, EFS and OS were significantly improved in those receiving early and delayed consolidation (EFS 87% (74-88) vs. 52% (41-70), and OS 92% (87-97) vs. 61% (51-71)(p=0.036). Prognostic factors for EFS identified in multivariable analyses were: age >10 years in the LR group (OR 3.5, 95% CI 1.3-9.5, p=0.01), and treatment with C-2 in IR patients (OR 5.0, 95% CI 1.4-17.8, p=0.01). The CNS relapse rate was 4% for all the series (including the HR subset). Tolerance to treatment was good.

INTERPRETATION AND CONCLUSIONS

In this study, early consolidation seemed to improve the prognosis of children with LR-ALL, but differences in EFS were not significant. Delayed consolidation had a favorable influence on the outcome of IR-ALL. CNS preventive treatment without cranial irradiation was effective in all the groups of ALL patients.