Mutations are caused when the cell's DNA is damaged. Sometimes mutations cause cancer but this is not always the case. However, more exposure to anything that cause mutations will increase the chance of developing cancer. Anything that causes a cancer is also sometimes called a carcinogen.
Picture 15. It's a smoker's choice.
Cancer causes
Roll over the pictures to see a description of some of the causes of this damage.
Cigarette smoke
Hydrocarbons found in the cigarette smoke cause cancers in places like the lungs, throat and stomach. The hydrocarbons cause errors to be made when cells copy their DNA. These errors cause mutations and so increase the chance of developing cancer.
Ionising radiation
Radioactive materials produce invisible radiation. There are three main types called alpha, beta and gamma radiation.
Although the radiation is invisible it carries a high amount of energy and penetrate into the body. If they collide with chromosomes they can cause damage to the DNA. This damage causes a mutation and increases the chances of developing cancer. There is more information on radiation in the section: Radiation - cause and cure.
Carcinogenic chemicals
Some chemicals can cause cancer. They are often molecules that interfere with the way the DNA is copied during cell division. This causes mutations and so increases the chances of developing cancer.
The use of carcinogenic chemicals is closely controlled.
Picture 16. Most radiation damage is caused by UV rays in sunlight.
Ultraviolet radiation in sunlight
Ultraviolet (or uv) radiation is a form of ionising radiation. It is found in sunlight and causes damage to the molecules in the skin. If this happens to DNA in skin cells it can cause skin cancer or malignant melanoma.
It is best to avoid exposure to sunlight and sun block cream should always be worn in strong sunlight.
Chance
Sometimes mutations just happen by chance. Mistakes can be made when cells copy their DNA during the normal process of cell division. If this mutation is in a gene that controls cell growth it can result in the cell growing uncontrollably and forming a cancer.
