Intellectual function after treatment for leukaemia or solid tumours.

Twenty three children who had been treated for acute lymphoblastic leukaemia (ALL) were evaluated intellectually using the British Ability Scales. Their treatment included early cranial irradiation, intrathecal chemotherapy, and systemic chemotherapy. Nineteen children who had been treated for various types of solid tumours (ST), had undergone related chemotherapy, and had received irradiation to sites of the body other than the cranium were used as controls. In addition, patients' siblings were assessed and their scores statistically corrected to produce a best estimate of the patients' pre-morbid degree of intellectual functioning. The results showed intellectual deficits after treatment in both patient groups, but these were consistently larger in the ALL group, particularly for the higher functions of intelligence. Intellectual deficit in ALL patients did not show immediately after radiotherapy but became progressively more apparent some time afterwards and particularly in younger children. In contrast, in the ST group, intellectual deficits seemed to diminish over time, and the age at radiotherapy was not a critical factor.