Pediatric Cancers

Abstract

Pediatric cancers include a broad spectrum of diseases. Cancer is diagnosed in only 8400 children in the United States less than 15 years of age annually, although death from cancer is the second major cause of mortality in developed countries. Childhood cancers differ from adult cancers in their origins and histologic subtypes, their etiologies, their response to treatment, and the outcomes. In the adult population, epithelial cancers are most common and many are related to environmental carcinogens. In contrast, pediatric malignancies more commonly arise in hematopoietic tissue or in the central nervous system (CNS). The most common pediatric malignancies are acute leukemia, non‐Hodgkin's lymphoma, Hodgkin's disease, and primary CNS tumors. Neuroblastoma, Wilms' tumor, rhabdomyosarcoma, and retinoblastomas are the most common solid tumors occurring in children. The etiology of most childhood malignancies is unknown, although some solid tumors do occur in association with recognized genetic defects. Bilateral retinoblastoma, for instance, occurs in children with mutations in the retinoblastoma tumor suppressor gene RB1 . Wilms' tumor occurs in association with mutations in the WT1 gene in the Denys‐Drash Syndrome. Rhabdomyosarcomas are seen in children with the LiFraumeni syndrome with p53 gene mutations. Major advances in cancer genetics and the molecular biology of cancer have been gained through research in pediatric malignancies. Despite its rarity in comparison to adult malignancies, many of the most important discoveries about cancer biology and cancer genetics have come from research in pediatric cancers. In addition, the role of prognostic factors in determining treatment for an individual patient is best exemplified by neuroblastoma which is discussed in this chapter. At the present time, only a limited number of cancers in children have prognostic factors that have been prospectively evaluated and confirmed. In this chapter, we review those pediatric cancers that have clearly defined prognostic factors. The understanding of cancer genetics gained from the study of pediatric cancers, the identification of prognostic factors, their confirmation in clinical trials, and their widespread acceptance can be viewed as a paradigm for prognostic factors in cancer patient management.