ABSTRACT
Cancers in children account for well under 2% of all cancer worldwide, but a much larger proportion of total life-years potentially lost to cancer. Leukemia is the most frequent childhood cancer. Central nervous system tumors are the most common group of solid tumors, and solid tumors overall are histologically much more diverse in children than in adults. In 2018 there will have been 200,000 newly diagnosed cases of childhood cancer worldwide. This chapter begins with an account of the descriptive epidemiology of childhood cancer. It covers the principal variations in incidence rates and patterns of occurrence worldwide, with brief discussions of survival and mortality. Childhood cancers are linked to numerous genetic syndromes, and germline mutations in cancer-predisposition genes can be detected in almost 10% of cases. Findings on the risk of childhood cancer associated with other birth characteristics are discussed. This is followed by a review of the exogenous factors most convincingly implicated in the etiology of childhood cancer. Certain infections and ionizing radiation are most firmly established. Evidence for the role of other environmental exposures is less conclusive, and there is widespread inconsistency between studies.
