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.

Atypical Teratoid Rhabdoid Tumor: Two Case Reports and an Analysis of Adult Cases with Implications for Pathophysiology and Treatment

“…Tumors of infancy in general are thought to arise from cells that have not completed the process of terminal differentiation and continue to undergo hyperplasia from the latter half of pregnancy to age 3 or so (34). …”

“…ATRT may be said to be the prototypical tumor of infancy, in having the earliest onset and highest perinatal incidence of such tumors. Tumors of infancy in general are thought to arise from cells that have not completed the process of terminal differentiation and continue to undergo hyperplasia from the latter half of pregnancy to age 3 or so ( 34 ).…”

Origins of Second Malignancies in Children and Mutational Footprint of Chemotherapy in Normal Tissues

“…Hypothetically, the cytotoxic therapies used for its treatment could have depleted during infancy normal growth stimuli necessary for SMARCB1 -null cells to fully develop into an MRT. As the diagnosis of this tumor coincided with incipient puberty, it is tempting to speculate that the associated changes in systemic growth stimuli facilitated the manifestation of these indolent SMARCB1 -null cells ( 37 ). Indeed, the form of presentation of MRT is statistically related to age.…”