Genetic testing for breast cancer

A blood or saliva sample can be checked for changes in genes linked with breast cancer risk. A positive result may explain a family pattern, support earlier or more frequent screening, or help relatives decide whether testing is useful. It does not prove that cancer is present. A negative result may lower concern about the particular changes tested, but it cannot remove every possibility of breast cancer. Some results are uncertain because their effect is not yet clear. Inherited testing is different from a breast cancer gene expression test, which examines features of tumour cells after cancer has been diagnosed.

Ask for genetic counselling before testing when possible. The counsellor can review relatives’ diagnoses, explain what the test can and cannot detect, and discuss privacy and implications for family members. Share the result with the clinician coordinating your breast care. Your plan may include a mammogram or breast MRI, depending on your personal and family history. If cancer has already been found, testing of inherited genes may sit alongside biopsy findings and genomic tumour profiling rather than replace them.

Arrange a clinical review if you have a new breast change, a close relative with breast or ovarian cancer, cancer diagnosed at a younger age in the family, or several relatives with related cancers. A new lump, nipple change, skin change or unusual discharge needs assessment whether or not genetic testing is planned. Testing is a risk assessment tool; it does not delay examination of a concerning change.

Which genes and types of changes will this test cover? What would a positive, negative or uncertain result change for my screening or treatment? Should an affected relative test first? How will the result be recorded and shared with relatives?