The longitudinal effects of medical treatment on the intellectual functioning and academic achievement of pediatric oncology patients

Children with leukemia and lymphoma receive central nervous system (CNS) prophylactic treatment because they are at considerable risk for CNS relapse. Accumulating evidence indicates that CNS prophylactic treatment with cranial or craniospinal radiation therapy (CRT) and intrathecal chemotherapy (ITC) contributes to significant negative effects, including impairment in intelligence test performance and academic achievement among children who survive the disease and its treatment. Effective CNS prophylaxis with ITC alone has been developed and is currently in use at The University of Texas M. D. Anderson Cancer Center where the subjects for this study were treated.

The intelligence test performance and academic achievement of children treated with ITC (N = 19) was compared to the performance of children with solid tumors (ST) and Hodgkin's disease (HD) who were treated with systemically administered chemotherapy (No ITC) (N = 21). Patients were assessed at the time of diagnosis and three annual follow-ups with an abbreviated form of the WISC-R, the WRAT-R Spelling and Arithmetic subtests, and the PIAT Reading Recognition and Reading Comprehension subtests.

Results were analyzed using repeated measures analysis of variance with treatment group (ITC and No ITC) and gender as between subjects variables and time of test (4) as a repeated measures factor. Demographic variables, disease relapse, school absenteeism, and baseline measures were examined as potential predictors of performance using multiple regression analyses.

Results on composite IQ scores indicated that the children in the ITC and No ITC treatment groups performed within the average range of functioning and demonstrated relatively consistent performance on composite IQ scores, IQ subtest scores, and IQ factor scores across time. Baseline results found a significant number of these children demonstrated significant VIQ < PIQ discrepancies. An examination of arithmetic achievement found a significant decline at the third annual follow-up within the ITC treated group.

Analysis of IQ-academic achievement discrepancy scores found significant time of test main effects on seven of thirteen discrepancy scores with IQ exceeding assessed academic achievement. Significant group effects were found on all three of the IQ-arithmetic discrepancy scores indicating that children in the ITC group declined in assessed arithmetic achievement relative to IQ performance, while the No ITC group began with substantial discrepancy scores and performed consistently across time. Eight of the thirteen time of test main effects for IQ-academic achievement discrepancy scores were significant for males, while none of these effects were significant for females.

Age at diagnosis was found to be a significant predictor of IQ and achievement at the final assessment within the No ITC group, but was not as strong a predictor of performance within the ITC group. School absenteeism, relapse, and demographic variables were not significant predictors of performance at the three-year follow-up.

These findings are discussed in terms of the implications for CNS prophylactic treatment and apparent risk factors for the development of academic achievement problems. Research is cited that established a relationship between cerebral development, immunological disorders, and learning problems. Cautions are provided regarding the use of ST £ind HD control groups to evaluate the effects of CNS prophylactic treatments. Similar studies using neuropsychological measures and longitudinal investigations of a more extended duration are suggested for future research on the effects of medical treatment with ITC.