The effects of prophylactic treatment of the central nervous system on the intellectual functioning of children with acute lymphocytic leukemia.

The effect of central nervous system prophylaxis (cranial radiation and intrathecal chemotherapy) on intellectual function was studied in 24 children with acute lymphocytic leukemia. The Wechsler Intelligence tests were administered to these children and to a sample of their healthy siblings, who served as a comparison group. The mean Full Scale lQ was 98.6 for the patients and 112.5 for the sibling controls (p less than 0.001 level). Those patients who received central nervous system preventive treatment at a young age exhibited a greater decrement in intellectual abilities than did patients who were older when they received this treatment. In contrast, leukemia patients who had not received central nervous system prophylaxis had IQs that did not differ statistically from those of their siblings. These data suggest that central nervous system prophylaxis may have an adverse effect on the intellectual capability of children with acute lymphocytic leukemia.