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Breast cancer - managing family history - Management
How is genetic testing carried out?

  • Genetic testing is appropriate only for a small number of women from high-risk families and is possible only if there is a living relative with the disease who is willing to be tested.
  • Genetic testing is a two-stage process. It begins with a search for a genetic mutation in a relative with cancer to try to identify a mutation in the appropriate genes (BRCA1, BRCA2, and if the pedigree warrants it the TP53 gene as well). It may also be appropriate to test for a less common gene if the clinical features suggest a particular gene such as PTEN (Cowden's syndrome).
  • If, in the initial testing of the relative with cancer:
    • A causative mutation is not found: the unaffected woman who initially presented should be informed that genetic testing on her or any other unaffected family member is unlikely to be informative and is not recommended. However, the absence of an identifiable gene fault does not mean that there is definitely not one present (not all gene faults can be identified).
    • A causative mutation is found: a predictive test (family-specific mutation test) is made available to all female blood relatives, including the unaffected woman who initially presented.
      • If the predictive test is negative, the unaffected woman who has been tested should be reassured that a specific causative gene that was found in her relative has not been found in her, and there is no risk of transmitting that particular gene fault to her children. Her risk of breast cancer is the same as that of the general population.
      • If the predictive test is positive, this means that the woman has inherited the gene fault from her relative and her risk of cancer is increased. Each of her children has a 50% risk of inheriting the gene fault.
    • The Department of Health have set the following standards for the time taken for the results of genetic tests to be available:
      • Within 2 weeks, where the potential genetic mutation is already known (such as where another family member has already been tested).
      • Within 8 weeks, for unknown mutations in a large gene.

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