These include (1) Leukemia, the most common pediatric cancer (representing approximately 28% of childhood cancer cases) Brain and other central nervous system tumors (26% of cases) Lymphomas (19% of cases) Osteosarcoma and Ewing sarcoma (4% of cases) Cancers that occur exclusively in children include (1) Neuroblastoma (6% of cases) Wilms tumor (4 to 6% of cases) (2, 3) Rhabdomyosarcoma (3% of cases) Retinoblastoma (2% of cases) In the US in 2018, it was estimated that there were 483, 000 survivors of childhood cancer (ie, first diagnosed before age 20; 4).