Leukemia is the most common cancer of childhood. The body produces lymphocytes to protect the body from infection, in leukemia these cells do not mature properly and become too numerous in the blood and bone marrow. Leukemia may be acute or chronic. The most common type is acute lymphoblastic leukemia (ALL). There are a number of other less common acute types which may be grouped together as acute non-lymphoblastic leukemia (ANLL), this includes acute myeloid leukemia (AML).
Childhood liver tumors are rare. There are two main types of liver cancer; hepatoblastoma and hepatocellular carcinoma. Liver cancer can be found in children of all ages; Hepatoblastomas are more common in patients aged under 3 years, while hepatocellular carcinomas are usually found in patients aged under 4 or between the ages of 12 and 15.
The lymphatic system helps the body fight infection. There are two main types of cancer associated with the lymphatic system: Hodgkin's Disease and Non-Hodgkin's Lymphoma (NHL). Both are rare in children aged under 3, and are more common in older children and adults. More boys than girls have childhood Hodgkin's disease.
Ewing's sarcoma / Peripheral Primitive Neuroectodermal Tumors (PNET) of bone is a type of cancer usually found in children and young adults. The peak incidence is between ages 10 and 20, it is less common in children under 5 or in adults over 30. Ewing's s can occur in any bone in the body; the most common sites are the pelvis, thigh, lower leg, upper arm, and rib. The tumor is composed of small round blue cells. Ewing's sarcoma can also arise in soft tissue (extra-skeletal).
Osteogenic Sarcoma (osteosarcoma) is a bone forming cancer. It is the most frequent type of bone tumor and is most common between the ages of 15 to 25. Over 90% of tumors are located in the metaphysis (the growing ends of the bone), the most common sites are the bones around the knee which account for 80% of cases. Osteosarcomas vary greatly in radiological and pathological features and therefore needs careful diagnosis to differentiate this from other bone tumors. Most are high grade intramedullary osteosarcomas, about 5% are low grade lesions, some are secondary osteosarcomas (for example those caused by radiation therapy).