Purpose: The purpose of this study was to determine the evolution of neurocognitive problems from therapy completion to long-term follow-up in survivors of childhood acute lymphoblastic leukemia treated with chemotherapy only.
Methods: We evaluated whether attention problems observed at therapy completion evolve into long-term executive dysfunction in 158 survivors treated on a single institution protocol. Treatment data (high-dose intravenous methotrexate exposure [serum concentration] and triple intrathecal chemotherapy injections) were collected. Parent report of behavior and direct cognitive testing of survivors was conducted at end of therapy, and survivors completed neurocognitive testing when > 5 years post-diagnosis.
Results: At the end of chemotherapy, survivors (52% female; mean age 9.2 years) demonstrated higher frequency of impairment in sustained attention (38%) and parent-reported inattention (20%) compared to population expectations (10%). At long-term follow-up, survivors (mean age 13.7 years; 7.6 years post-diagnosis) demonstrated higher impairment in executive function (flexibility 24%, fluency 21%), sustained attention (15%), and processing speed (15%). Sustained attention improved from end of therapy to long-term follow-up (p < 0.001). Higher methotrexate AUC and greater number of intrathecal injections were associated with attention problems (p = 0.009, p = 0.002, respectively) at the end of chemotherapy and executive function (p < 0.001, p = 0.02, respectively) problems at long-term follow-up. Attention problems at the end of therapy were not associated with executive function problems at long-term follow-up (p's > 0.05). The direct effect of chemotherapy exposure predicted outcomes at both time points.
Conclusions and implications for cancer survivors: Survivors should be monitored for neurocognitive problems well into long-term survivorship, regardless of whether they show attention problems at the end of therapy. Treatment exposures are the best predictor of long-term complications.
Keywords: Attention, executive function; Behavior; Chemotherapy; Childhood acute lymphoblastic leukemia; Childhood cancer.