Cancer is a disease in which cells divide out of control.
With specific types of gene damage, the cell starts dividing out of control, forming a tumor.
Cancer and tumors are a result of specific types of gene damage.
Cancer and tumors are a result of specific types of:

1. organs
2. cigarettes
3. radiation
4. layers of fat
5. gene damage
6. rays or beams
7. Chemical energy
8. the skin