Some types of cancer can run in families. For example, your risks of developing certain types of breast cancer , bowel cancer or ovarian cancer are higher if you have close relatives who developed the condition. This doesn't mean you'll definitely get cancer if some of your close family members have it, but that you may have an increased risk of developing certain cancers compared to other people.
It's estimated that between 3 and 10 in every cancers are associated with an inherited faulty gene. Doctors call this having a genetic predisposition to cancer. For a cancer to develop, further gene changes mutations need to happen. This usually happens over many years. Cancers due to inherited faulty genes are much less common than cancers due to gene changes caused by ageing or other factors.
Most cancers develop because of a combination of chance and our environment, not because we have inherited a specific cancer gene fault. Different gene faults increase the risk of different types of cancer.
Some faults increase the risk by a small amount and some increase the risk much more. Read about inherited genes and cancer types. Most people who have relatives with cancer will not have inherited a faulty gene. Cancer mostly occurs in older people. It is a common disease. So, most families will have at least one person who has or has had cancer. In families with an inherited faulty gene, there is usually a pattern of specific types of cancer running in the family.
The strength of your family history depends on:. This means that it is more likely that the cancers are being caused by an inherited faulty gene. It is important to remember that cancer is most common in older people. Cancer in older people is less likely to be due to an inherited cancer gene.
Talk to your GP if you think that you may have a strong family history of cancer. If they think that you might be at increased risk, they can refer you to a genetics clinic. In this section you can learn more about the complex links between genes and cancer.
Advances in genetics and molecular biology have improved our knowledge of the inner workings of cells, the basic building blocks of the body. Cancer is such a common disease that it is no surprise that many families have at least a few members who have had cancer. About 5 to 10 percent of cancers are thought to be hereditary.
In these cases, an individual inherits a copy of a growth control gene with a mutation from one parent, and a working copy of the same gene from the other parent. The gene with the mutation is also called a "cancer susceptibility gene. However, if the working copy of the gene in a cell becomes damaged by a mutation, that cell can lose its growth control and become cancerous.
Thus, individuals who inherit a cancer susceptibility gene have a much greater chance for developing certain cancers in their lifetime. However, not everyone with an inherited cancer susceptibility gene will develop cancer. Damaged cancer susceptibility genes can be inherited, and passed on, by men just as easily as women.
If a parent carries a cancer susceptibility gene, each of their children has a 50 percent chance of inheriting the gene, and thus the susceptibility to cancer.
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