Cancers are due to changes in a person's genetic material, the genes.
Genes are present in almost every cell of the body, and are responsible for producing the chemicals that make the body grow and develop. The genes are composed of DNA and are located on the chromosomes, with each gene having its own place on its own chromosome. Almost all cells contain all the DNA needed to make a complete person. Suppressor genes are one way a skin cell, for example, ensures that only the genes needed to make skin cell products are active. It is as if there is a piano in each cell, with only certain keys allowed to play in different cell types.