Many cancers that affect children can be treated, but cancer remains an important cause of child mortality, with an estimated 80 000 cancer-related deaths in children per year worldwide. Although childhood cancer survival rates are about 80% in high-income countries, they may be as low as 10% in some countries.
Compared with the adult population, children are affected by different types of cancer. Almost half of childhood cancers are cancers of blood cells (leukaemia and lymphoma), and the most frequent other malignancies are tumours of the central nervous system and tumours that develop from embryonal tissues. Carcinomas, which are the predominant type in adults (breast, lung, or stomach cancer), are extremely rare in children.