Oncology. Most common type of cancer in children (about 35 %). Most cases of childhood leukemia occur in the age group of 1 to 5 years. The disease is more prevalent in boys than girls. The main morphological subtypes are acute lymphoblastic leukemia (ALL), which accounts for over 80 % of all childhood cases and acute myeloblastic leukemia (AML). Chronic forms of leukemia are rare in children. Advances in diagnosis and treatment have resulted in more than 80 % of children diagnosed with leukemia surviving into adulthood.