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Depending on your family history, your doctor may refer you to a family history or genetics clinic, and you might be offered genetic testing. This aims to identify whether genetic faults linked to breast cancer run in your family, and whether you have inherited these.
About one in every four women with breast cancer and a family history of the disease is thought to have inherited a fault in a known breast cancer gene, such as BRCA1 or BRCA2. Genetic testing through the NHS can detect faults (changes or mutations) in the BRCA1 and BRCA2 breast cancer genes that can increase the risk of developing breast cancer.
NHS genetic testing
Currently, the NHS only offers genetic tests to people with a family history of breast cancer that suggests they are reasonably likely to have inherited faults in breast cancer genes. These are people for whom it is estimated that there is at least a one in 10 chance that they carry BRCA1 or BRCA2 gene faults. A genetics healthcare professional will calculate your probability of carrying faulty BRCA genes and let you know whether you qualify for genetic testing on the NHS.
Families where there are childhood sarcomas (cancer of connective tissue) and brain tumours as well as breast cancer may also be tested for faults in the TP53 gene. Faults in this gene are extremely rare but can increase the risk of breast and other cancers.
If you are eligible for genetic testing and are considering it, you should be offered genetic counselling before any testing occurs.
There are usually two stages to genetic testing:
Stage 1: Diagnostic testing (mutation searching)
This aims to identity whether genetic faults in known breast cancer genes run in the family. It usually involves searching the DNA of a relation in the family who has – or has had – breast cancer to see if there is a fault in one of their breast cancer genes. If a fault is found, then stage 2 – predictive testing – is possible.
If a relative diagnosed with breast cancer is not available for genetic testing, it is now possible for a family member who has not had breast cancer to be tested.
Stage 2: Predictive testing
This aims to determine whether other members of the family have inherited the same genetic fault. Family members who have inherited the fault are at increased risk of breast cancer, while those who have not inherited it have the same risk of breast cancer as the general population.
Direct genetic tests
Some companies offer genetic testing directly to the public without a medical appointment. There is little evidence that these direct genetic tests can predict breast cancer risk, and they usually do not test for faults in BRCA1 or BRCA2. They are also not carried out alongside appropriate genetic counselling. Breakthrough does not recommend the use of direct genetic tests.
Information last reviewed: 12 August 2013