Long-term consequences of CNS treatment for childhood cancer, part I: Pathologic consequences and potential for oncogenesis

The pathologic changes associated with the treatment of cancer of the nervous system are reviewed. Computed tomographic, magnetic resonance imaging, and positron emission tomographic findings of these abnormalities are described, followed by discussion of the known histopathologic features. For the most part, pathologic effects are primary vascular and/or demyelinating. We review each of these effects at all levels of the neural axis. This review concludes with a discussion of the risk of developing second malignancies. Although this complication is infrequent, the likelihood that survivors of childhood cancer will develop a second malignancy is 10 times that of age-matched controls. This phenomenon in part relates to genetic predisposition, environmental factors, and host susceptibility. These qualifications not withstanding, most studies implicate central nervous system radiation with and without chemotherapy as the primary etiology for second malignancies.