Genes play a role in all cancers.
Most cancers occur by chance, as the result of damage to our genes.
Many genes in the human body help to control how our cells divide and grow. Gene mutations may be caused by aging, exposure to chemicals, radiation, hormones or other factors within the body and the environment. Over time, a number of gene mutations may occur in a cell, allowing it to divide and grow in a way that becomes a cancer. This is probably because a cell has to undergo several gene mutations before it becomes a cancer. About 1 out of every 3 people will have some kind of cancer at some time if they live long lives.