Cancer in children can occur anywhere in the body, including the blood and lymph node system, brain and spinal cord (central nervous system; CNS), kidneys, and other organs and tissues.

Cancer begins when healthy cells change and grow out of control. In most types of cancer, these cells form a mass called a tumor. A tumor can be cancerous or benign. A cancerous tumor is malignant, meaning it can grow and spread to other parts of the body. A benign tumor means the tumor can grow but will not spread to distant parts of the body.

In leukemia, a cancer of the blood that starts in the bone marrow, these abnormal cells very rarely form a solid tumor. Instead these cells crowd out other types of cells in the bone marrow. This prevents the production of:

Normal red blood cells. Cells that carry oxygen to tissues.

White blood cells. Cells that fight infection.

Platelets. The part of the blood needed for clotting.

Most of the time, there is no known cause for childhood cancers. Childhood cancers may behave very differently from adult cancers, even when they start in the same part of the body.

Cancer is uncommon in children. Most cancers (99%) develop in adults, and it is most common in older adults. About 1 out of every 3 adults will develop cancer during his or her lifetime, while about 1 in 285 children will develop cancer before the age of 20.

At the same time, there is a lot of research going on to discover new treatments for childhood cancer. This research has greatly improved the overall survival rate for children with cancer, which is now more than 80%.

On this app: You will find some basic information about this disease and the parts of the body it may affect. This is the first page of Cancer.Net’s Guide to Childhood Cancer. Use the menu to see other pages. Think of that menu as a roadmap for this complete guide.