Breast Cancer Genes and Genetic Testing

An inherited test usually uses blood or saliva to look for a harmful variant present from birth. Tumour testing examines cancer cells for acquired changes or patterns that may help describe the cancer and guide some treatment decisions.

Genes carry instructions that help cells grow, divide and repair damage. A harmful inherited variant in certain genes can raise susceptibility to breast and other cancers, yet it does not mean cancer will definitely develop. Breast cancer can also occur without a known inherited variant.

Changes found only in tumour cells are acquired during life and are not automatically passed through a family. A gene expression test or broader tumour profile may estimate aspects of tumour behaviour or identify treatment-relevant features. The test name, specimen and question being asked determine how a result should be interpreted.

Collect cancer diagnoses from both sides of your biological family, including the cancer type and age at diagnosis when known. Genetic counselling can explain which person in a family is most informative to test, possible results, limits of the panel and whether a finding could matter to blood relatives.

Ask whether the proposed test looks for inherited variants, tumour changes or gene expression. Results may be positive, negative or uncertain. An uncertain variant should not be treated as proof of increased risk; specialists interpret it alongside personal history, family history and later laboratory updates.

Discuss genetic counselling when breast cancer occurs in several close relatives, at unusually young ages, in both breasts, in a man, or alongside related cancer patterns. A known harmful inherited variant in a blood relative is also a clear reason to ask about targeted testing.

Genetic risk does not change the response to a symptom. Arrange prompt clinical care for a new breast or armpit lump, nipple discharge or inversion, skin dimpling, or an unexplained breast-shape change, whether genetic testing is planned, negative or still pending.

Ask what the result could change for screening, risk-reduction choices or cancer treatment; whether genetic counselling is available; who owns and can access the result; and which relatives might benefit from information. Request a copy of the laboratory report with the exact gene and variant classification.