Editor’s note: This is part two of a three-part series.

Last week we discussed what cancer is, and how it begins when microscopic cells that make up a normal body part start growing out of control. This week we’ll discuss some of the different types of childhood cancer.

Leukemias are the most common, accounting for about one-third of all childhood cancers. Leukemia is a type of cancer that originates from white blood cells, which normally help fight infection. Leukemia generally begins in the bone marrow where blood cells are formed, but eventually the cancerous cells are released out into the bloodstream so there is no distinct “tumor.”

There are different kinds of leukemias, such as ALL or AML, depending on the type of white blood cells that are growing out of control. The leukemia cells crowd out production of normal white blood cells, and also normal red blood cells and platelets. Early symptoms may therefore include unexplained fevers or unusual infections, paleness and tiredness due to low red blood cells (anemia) and easy bruising or bleeding because of low platelets, which help clot the blood. Children with leukemia may also experience bone or joint pain and weight loss.

Brain cancer is the second most common type of childhood cancer, accounting for about 20 percent of the total. The brain itself is made up of many different parts comprised of various types of cells, so there are many kinds of brain tumors that can form when those cells grow out of control. The symptoms depend largely on exactly where in the brain the tumor has formed, since the normal function of nearby brain structures will be affected. Headaches, often with vomiting, are common. Other symptoms may include sudden onset of vision changes, behavior or personality changes, or trouble with balance, tremors, or weakness. Brain tumors rarely metastasize, or travel to other parts of the body.
While still relatively rare, bone cancers occur more commonly during adolescence. The two main types, Ewing’s sarcoma and osteosarcoma, typically cause varying degrees of localized bone swelling or pain. Bone tumors can metastasize to other organs, creating new tumors in places such as the lungs, lymph nodes and even other bones. Up to 20 percent will have metastasized by the time the initial bone cancer is discovered. Widespread metastasis makes treatment more difficult.

Childhood cancers are scary and potentially very dangerous. However, over 80 percent of children diagnosed with childhood cancers will survive five years past their diagnosis, quite different from even 25 years ago when the survival rate was less than 50 percent. For more information check out the following: or www.acco/awareness.

Next week we will discuss some of the general strategies and side effects of cancer treatment.

Sally Robinson is a clinical professor of pediatrics at UTMB Children’s Hospital. This column isn’t intended to replace the advice of your child’s physician.