What is a pediatric tumor?

Abstract

Working together with medical oncologists, the question of whether a Ewing sarcoma in a 25-year-old is a pediatric tumor comes up repeatedly. Like Ewing’s, some tumors present characteristically at ages that cross over what has been set as the definition of pediatrics (15 years, 18 years, or 21 years?). Pediatric oncology textbooks, surprisingly, do not address the subject of defining a pediatric tumor. They all begin with an epidemiology chapter defining the types of tumors appearing at distinct stages of childhood, adolescence, and young adulthood. Describing the epidemiology of tumors in relation to age, it becomes clear that the disease is related to the phenomenon of aging. The question, however, remains: is there a biological definition of what pediatric age is? And if so, will tumors occurring during this period of life have anything to do with such biological definition? With the aim of finding an objective definition, the fundamental concepts of what defines “pediatrics” was reviewed and then the major features of tumors arising during development were analyzed. The tumors were explored from the perspective of a host immersed in the normal process of growth and development. This physiological process, from pluripotential and undifferentiated cells, makes possible the differentiation, maturation, organization, and function of tissues, organs, and apparatus. A biological definition of pediatric tumors and the infancy–childhood–puberty classification of developmental tumors according to the infancy–childhood–puberty model of normal human development are proposed.