Childhood cancer (also known as pediatric cancer) is cancer in a child. In the United States, an arbitrarily adopted standard of the ages used are 0–14 years inclusive, that is, up to 14 years 11.9 months of age.[2][3] However, the definition of childhood cancer sometimes includes young adults between 15–19 years old.[3] Pediatric oncology is the branch of medicine concerned with the diagnosis and treatment of cancer in children.

Worldwide, it is estimated that childhood cancer has an incidence of more than 175,000 per year, and a mortality rate of approximately 96,000 per year.[4] In developed countries, childhood cancer has a mortality of approximately 20% of cases.[5] In low resource settings, on the other hand, mortality is approximately 80%, or even 90% in the world’s poorest countries.[5] In many developed countries the incidence is slowly increasing, as rates of childhood cancer increased by 0.6% per year between 1975 to 2002 in the United States[6] and by 1.1% per year between 1978 and 1997 in Europe.[7]

The most common cancers in children are (childhood) leukemia (34%), brain tumors (23%), and lymphomas (12%).[7] In 2005, 4.1 of every 100,000 young people under 20 years of age in the U.S. were diagnosed with leukemia, and 0.8 per 100,000 died from it.[8] The number of new cases was highest among the 1–4 age group, but the number of deaths was highest among the 10–14 age group.[8]

In 2005, 2.9 of every 100,000 people 0–19 years of age were found to have cancer of the brain or central nervous system, and 0.7 per 100,000 died from it.[8] These cancers were found most often in children between 1 and 4 years of age, but the most deaths occurred among those aged 5–9.[8] The main subtypes of brain and central nervous system tumors in children are: astrocytoma, brain stem glioma, craniopharyngioma, desmoplastic infantile ganglioglioma, ependymoma, high-grade glioma, medulloblastoma andatypical teratoid rhabdoid tumor.[9]

Other, less common childhood cancer types are:[9]

• Neuroblastoma (7%, nervous system)
• Wilms tumor (5%, kidney)
• Non-Hodgkin lymphoma (4%, blood)
• Rhabdomyosarcoma (3%, many sites)
• Retinoblastoma (3%, eye)
• Osteosarcoma (3%, bone cancer)
• Ewing sarcoma (1%, many sites)
• Germ cell tumors (many sites)
• Pleuropulmonary blastoma (lung or pleural cavity)
• Hepatoblastoma and hepatocellular carcinoma (liver cancer)