Abstract
Traditional criteria and definitions for response and relapse are not completely suitable for children with brain tumors. Response and relapse for brain tumors need to be defined using the most objective criteria available, that is, the computed tomography (CT) scan findings. Relapse may also be defined by myelography, cerebrospinal fluid analysis, or biopsy of extraneural disease. Standardization of response and relapse will lead to meaningful comparisons of patients treated with various therapies. Cancer 56: 1824‐1826, 1985.