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The Five Most Common Pediatric Cancers in the U.S.

 Interestingly, the types of cancers that develop in children are different than those that occur in adults.3 According to an article published in CURE Magazine:

The difference between childhood and adult cancers rarely comes down to simply age. Most tumors in children differ biologically from their adult counterparts, and are typically due to the type of cell from which the cancer originates. In the weeks after fertilization, the embryo develops into layers: ectoderm, mesoderm, and endoderm. These layers lay the foundation for the development and maturation of tissues and organs in the body. Adult cancers, such as lung, breast, and colorectal, typically develop from epithelial tissue (adenocarcinomas), which come from the ectoderm or endoderm. Epithelial cells make up the skin and lining of the internal organs and glands. Alternatively, childhood cancers, including sarcomas (cancers of the bone or muscle) and leukemia (blood cancers), develop from the mesoderm.4

The most common pediatric cancer is acute lymphoblastic leukemia (ALL), accounting for 34 percent of all pediatric cancers. Leukemia begins in the bone marrow and spreads to the blood. This type of cancer typically occurs between the ages of two to four years and is more common in males than females.3

Brain tumors and nervous system tumors constitute about 27 percent of pediatric cancers.

Most brain tumors in children typically begin in the lower part of the brain.3 Neuroblastoma, a type of cancer than develops in certain types of nerve tissue, accounts for seven percent of pediatric cancers. It is more common in males under the age of five.3

Wilms tumor is the fourth common type of pediatric cancer affecting the kidneys and children between the ages of three to four years. Wilms accounts for five percent of all pediatric cancers.3

Lymphoma is the fifth most common type of pediatric cancer and occurs in a very small percentage of children. This type of cancer begins in immune system cells known as lymphocytes.3

Cause of Most Pediatric Cancers Has Yet to be Determined
The search for the causes of pediatric cancers has been systematically studied over the last few decades. However, there are no conclusive answers on what is causing children to develop cancer.5

According to NCI and a report published in Pediatric Clinics of North America, five to 10 percent of pediatric cancers are believed to be caused by an inherent genetic mutation, a mutation that can be passed on from parents to their child.6 For example, 25 to 30 percent of retinoblastoma, a cancer of the eye that occurs in primarily in children, is believed to be caused by an inherited gene mutation known as RB1.6

Nonetheless, retinoblastoma only accounts for four percent of pediatric cancers and the cause of the remaining 70 percent of cases is still unknown.6

In another example, children with a genetic condition known as Down Syndrome are ten to twenty times more likely to develop leukemia than children without Down Syndrome. However, only a very small proportion of pediatric leukemia is associated with Down Syndrome.6

Image courtesy of: UT Austin

Studies have shown that that besides high dose radiation and prior chemotherapy, there are very few external or environmental risk factors known to be associated with pediatric cancers.5 Environmental factors refer to exposures children are exposed to that originate outside the human body.5