The relationship of sex and treatment modality to neuropsychologic outcome in childhood acute lymphoblastic leukemia.
PURPOSE: Long-term adverse neurobehavioral sequelae frequently are observed in pediatric patients treated for acute lymphoblastic leukemia (ALL). To clarify the relative contribution of cranial irradiation (CRT) therapy and drug therapy to these outcomes, we evaluated neuropsychologic outcomes associated with different doses of CRT and intravenous (IV) methotrexate (MTX) in long-term survivors. PATIENTS AND METHODS: Fifty-one patients treated for ALL on Dana-Farber Cancer Institute protocol 81-01 were evaluated by standardized cognitive and academic achievement tests. These children had been assigned at diagnosis to a standard-risk (SR) or high-risk (HR) group and received 1,800 cGy or 2,800 cGy CRT, respectively. A subgroup of these patients was randomized to receive MTX during remission induction, either as a single low dose (LD; 40 mg/m2) or a single high dose (HD; 4 g/m2) with leucovorin rescue. RESULTS: Sex and MTX randomization jointly predicted the intelligence quotient (IQ). Fifty percent of girls versus 14% of boys exhibited low IQ (less than 90; P = .01); 80% of girls who received HD MTX versus 25% of girls who received LD MTX exhibited low IQ (P = .03). In contrast, risk group better predicted performance on tasks sensitive to verbal memory and/or coding. CONCLUSIONS: We conclude that (1) significant neurotoxicity occurred principally in girls; (2) increased dose intensity of IV MTX was associated with lower IQ, but only in girls; and (3) increased dose of CRT may have been associated with impairment of verbal memory and coding.