Difference in Outcome of Adolescents with Acute Lymphoblastic Leukemia (ALL) Enrolled in Pediatric (AIEOP) and Adult (GIMEMA) Protocols.

Progress in the treatment of acute lymphoblastic leukaemia (ALL) has led to better survival rates; however, children have had a greater benefit from improved treatment modalities than adolescent who show an overall lower event-free survival (EFS) compared to younger patients. Some differences in the clinical and biologic characteristics of adolescents compared to childhood ALL may partly account for the different outcome, but adolescents treated on pediatric ALL trials seem to have a significantly better EFS than those treated on adult trials. We retrospectively compared the results obtained in a series of 245 patients ranging in age from 14 to 18 years diagnosed and enrolled in specific Italian children and adult ALL trials, between 4/1996 and 10/2003. One hundred and fifty patients, from 30 pediatric centers, underwent the childhood AIEOP ALL 95 and 2000 protocols; the other 95, from 28 adult centers, were enrolled in the GIMEMA ALL 0496 and 2000 protocols. The AIEOP 95 and 2000 trials are BFM-like protocols with a 7 drug induction followed by risk-modulated post-remission therapy that includes high-dose MTX and reinduction for low and intermediate groups, and intensive blocks (high-dose MTX and cytarabine) for high-risk patients. Standard maintenance therapy is administered up to a total of 2 years. Cranial radiotherapy is limited to high-risk patients. Stem cell transplantation is planned for very high-risk patients. The GIMEMA regimens are instead based on an induction with high-dose anthracyclines (cumulative dose 550 mg/m²), high-dose cytarabine as consolidation and do not include high-dose MTX and the reinduction phase. Standard maintenance with vincristine + daunorubicin/cyclophosphamide pulses is given for 2 years. Cranial radiotherapy is administered to all patients. The main patients characteristics at diagnosis, in the two groups under examination, were comparable except for age: median age was 15 and 16 years, respectively in the AIEOP and GIMEMA trials.Poor risk cytogenetic translocations and T-immunophenotype were equally dinstributed. Adolescents in the AIEOP protocols had a higher CR rate (94% vs 89%) and a lower relapse rate (17% vs 45%) compared to the adolescents enrolled in the GIMEMA trials. The 2-year overall survival rate was 80% in the AIEOP protocols and 71% in the GIMEMA trials. Detailed results according to the different clinical and biologic features of the adolescents analyzed will be presented. The results of our comparative study indicate that adolescents enrolled in pediatric trials have a more favourable clinical outcome.