Hereditary cancer is cancer caused by inherited genetic variants, often referred to as mutations. The most common hereditary cancers are caused by variants in the BRCA1 and BRCA2 genes. These are known as BRCA-associated breast, ovarian, pancreatic and prostate cancers.
A genetic variant refers to a change in a gene. A gene is the basic unit that we inherit from our parents. Genes are made up of a series of DNA letters. A genetic variant occurs where there is a change in the arrangement of these letters, for example where letters are lost, gained or swapped for different letters. Some of these variants are harmless, whilst others can alter the function of a gene. When the variant is known to cause a genetic condition, such as hereditary cancer, it is may be referred to as a disease-associated variant or mutation.
Some genetic variants increase the risk of a person developing certain types of cancer. We inherit genes from both our parents so if a parent has a genetic variant then their child has a 50% (1 in 2) chance of inheriting it.
In a small proportion of men, there is a single genetic change, for example in the BRCA1 or BRCA2 genes, which plays a huge part in their risk of developing cancer. However, for most men it is not as simple as a single gene variant. It is thought there are many genetic changes that have a small individual effect, but together can add up to give a significant risk of developing prostate cancer.
Hereditary cancers are rare, especially if you are not part of a population group with a higher risk.
Across the entire population it is estimated that anywhere from 3 to 10 in 100 (3-10%) of all cancers are linked to an inherited genetic variant, although as we discover more about how our genes work, this estimate is likely to change.
Certain genetic changes are found more often in some populations. In particular, the Ashkenazi Jewish population has a higher frequency of some BRCA variants than the general population.
Most cancers are caused by faults in our genes that develop during our lifetime. They may happen as we get older due to random mistakes in our cells. It may also happen because of something we are exposed to, such as sunlight or cigarette smoke. These cancers are not inherited in our genes from our parents.
If you have a relative who has or has had cancer, you may be concerned that you are at a greater risk of developing cancer yourself. For most people, however, having a family member who has or has had cancer does not significantly increase their own risk of cancer.
Cancer is most common in older people and affects 1 in 2 people in the UK at some point in their lives. Most families will have at least one person who has or has had cancer, and most of the time this will not be hereditary cancer.
What increases your risk of hereditary cancer is if you have a number of relatives who have had the same type of cancer (or related cancers) and they were diagnosed at a relatively young age.
As a first step we would encourage you to fill out the Hereditary Cancer Risk Tool to assess your risk.
We would also advise that you talk to your GP about your family’s cancer history if you are concerned about hereditary cancer in the family. If appropriate, they will refer you to your regional genetics clinic where a genetic counsellor will provide you with support and information and will discuss with you whether genetic testing is an appropriate option.