Are all cancers hereditary?

No. Cancer is not really hereditary in the true sense of the word. Hereditary means that you definitely get a trait such as eye colour or an illness from the genes you inherit from your parents. The cause of cancer is not as simple as that. Cancers are not caused by just one gene. Cancer is usually an illness of older people and most cancers occur when several genetic changes occur in a cell. This is called sporadic cancer.

But some people inherit faulty (mutated) genes which make their chance of developing a particular cancer higher than normal. For example, women who have a faulty BRCA1 gene have an 80% chance of getting cancer at some point in their lives. But this still means that 1 in 5 women with this gene change will not get cancer. Up to 1 in 20 (5%) cancers are caused by an inherited faulty gene.

Cancers that may be caused by an inherited faulty gene and may seem to run in families include