Chemotherapy-only treatment effects on long-term neurocognitive functioning in childhood ALL survivors: a review and meta-analysis

Therapy for childhood acute lymphoblastic leukemia (ALL) is associated with 5-year survival rates of similar to 90% even after largely eliminating cranial radiation. This meta-analysis assesses the long-term neurocognitive functioning after chemotherapy-only regimens among survivors of childhood ALL. We conducted a systematic review to identify studies that evaluated long-term neurocognitive functioning following treatment of ALL by searching MEDLINE/PubMed, Database of Abstracts of Reviews of Effects, and secondary sources. Studies were included if ALL survivors were in continuous first remission, did not receive any radiation, were at least >= 2 years off therapy or >= 5 years since diagnosis, and were compared with a healthy control group. Weighted mean differences with 95% confidence intervals (CIs) were calculated. Ten nonexperimental studies met all eligibility criteria and included 509 patients and 555 controls. Meta-analysis demonstrated statistically significant moderate impairment across multiple neurocognitive domains evaluated, with intelligence most affected. Significant differences in standard deviation (SD) scores were found for Full Scale intelligence quotient (IQ) (-0.52 SD; 95% CI, -0.68 to -0.37), Verbal IQ(-0.54 SD; 95% CI, -0.69 to -0.40), and Performance IQ (-0.41 SD; 95% CI, -0.56 to -0.27); these SD scores correspond to changes in IQ of 6 to 8 points. Working memory, information processing speed, and fine motor domains were moderately, but statistically significantly, impaired. Meta-analysis of ALL survivors treated without cranial radiation demonstrated significant impairment in IQ and other neurocognitive domains. Patients and their families should be informed about these potential negative effects to encourage surveillance and educational planning. Both preventive and intervention strategies are needed.