There are many types of childhood cancers and they produce different conditions. Childhood cancers can occur in bones, blood or organs. Some cancers appear in the form of tumors while others occur in the blood. Childhood cancers include:

• Leukemia. Cancer of the bone marrow that results in malignant blood cells. Leukemia is the most common form of childhood cancer, accounting for 30 percent of all childhood cancers. There are two main types that occur in children:
  
• • Acute lymphoblastic leukemia (ALL). A cancer of the lymphoid cells in the bone marrow and the lymphoid organs of the body. ALL accounts for 78 percent of all childhood leukemia cases.
    
    
  • Acute myeloid leukemia (AML). A cancer of the myeloid white blood cells (non-lymphoid), which are produced in the bone marrow.
    
    
• Cancers of the central nervous system.
  
• • Brain tumors. The most common types of brain tumors found in children are called gliomas.
    
    

    

  • Spinal cord tumors. Less common than brain tumors.
    
    
• Neuroblastoma. Solid tumor that exists outside of the brain (extracranial). This tumor can appear anywhere in the body but usually occurs in the abdomen.
  
  
• Bone cancer.  Primary bone cancer is most often seen in children and adolescents.  Metastatic bone cancer (cancer that has spread to the bone) is more common than primary bone cancer in adults. The more common forms of bone cancer in children include:
  
• • Osteosarcoma. Most common type of primary bone cancer in children. These tumors often are located at the end of long bones, close to the joints, and are associated with rapid bony growth.
    
    
  • Ewing’s sarcoma.  Less common type of primary bone cancer that can occur anywhere along the bone.
    
    
• Rhabdomyosarcoma. Most common soft tissue cancer in children. This tumor starts from skeletal muscle cells.
  
  
• Wilms tumor. A cancer that can affect one or both kidneys. It is most often found in children between 2 and 3 years of age.
  
  

  

• Germ cell tumors.  These tumors can develop in several different locations but most commonly appear in the testicles, ovaries and the bottom of the spine. These tumors occur in young children and adolescents as well as adults.
  
  
• Liver cancers. An abnormal growth (tumor) in the liver. The types of liver cancer found in children are:
  
• • Hepatoblastoma. Most common in infants or very young children, between two months and two years of age.
    
    
  • Hepatocellular carcinoma. Occurs most frequently in children between the ages of 10 and 16 years.
    
    
• Lymphomas. Tumors of the lymph tissues, which are part of the immune system. The types of lymphoma are:
  
• • Hodgkin’s lymphoma. Sometimes called Hodgkin’s disease. This cancer starts in the lymphatic tissue, which includes the lymph nodes, and organs related to the immune system. In children, it is rare before the age of five and usually diagnosed in adolescents. Only 10 to 15 percent of the cases are diagnosed in children 16 years of age and younger.
    
    
  • Non-Hodgkin’s lymphoma. This cancer also starts in the lymphoid tissue and occurs one and a half times as often as Hodgkin’s lymphoma in children.