Participation in a Clinical Trial Does Not Impact Outcome in Pediatric Acute Lymphoblastic Leukemia

Background: Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy. Over the past four decades, the outcome for pediatric ALL has rapidly improved secondary to the participation of children on clinical trials, resulting in standardization of the treatment. Some have argued that the best outcome results from participation in a pediatric clinical trial. To address the potential benefits and barriers to participation in a clinical trial, we analyzed clinical trial participation in pediatric ALL at a large single institution.

Methods: We evaluated 322 ALL patients < 22 years old at diagnosis who receive their initial therapy at Seattle Children’s Hospital Regional Medical Center (S-CHRMC) between January 1997 and December 2005. Using a retrospective chart review, we analyzed the following variables: study participation (SP) or non-participation (NP) in an ALL therapeutic study, gender, race, patient immunophenotype, risk group (standard risk (SR), high risk (HR) or infant), home state, and distance of primary residence from S-CHRMC. S-CHRMC is the largest pediatric cancer center in the Pacific Northwest, with referrals from Washington, Alaska, Montana, Idaho and Wyoming. Events were defined as relapse or death from any cause.

Results: The overall 5 year event free survival (EFS) was 78% (+/− 2.5%). 157 patients participated in a treatment research study (49%). Only risk group was associated with EFS. SP and NP had similar EFS. Gender, race, immunophenotype, home state, or distance from primary residence were not associated with outcome. There was no difference in study participation by gender, race, home state, or distance of primary residence. There were trends to increased participation in SR vs HR (54% vs 35%, p value 0.15) and B lineage vs T lineage (50% vs 35%, p value 0.11).

Discussion: Participation in a research study for treatment of pediatric ALL was not associated with improved outcome in our large single institution series. Study participation was not different by clinical features, including distance to the primary residence. Strict standardization of treatment for all patients may contribute to the similar outcome for SP and NP.