Most breast cancers are sporadic; that is, they arise without a family pattern. But about 5–10% are linked to an inherited gene change. The best known are the BRCA1 and BRCA2 genes; these normally do the protective job of repairing DNA damage, and when they carry a change, cancer risk rises markedly.
How much does the risk rise?
Whereas the lifetime risk of breast cancer in the general population is about 12–13%, in people with a BRCA1/2 change it can rise to roughly 60–70% by age 80; the risk of ovarian cancer also rises. The figures vary from source to source and from family to family, so personal evaluation with a genetic counsellor is needed.
Who is advised to have genetic testing?
- People diagnosed with breast cancer before age 50
- People diagnosed with triple-negative breast cancer (usually regardless of age)
- People with cancer in both breasts, or both breast and ovarian cancer in the same person
- People whose family has several cases of breast/ovarian, prostate or pancreatic cancer
- People with a history of male breast cancer
- People who have a relative with a known BRCA change
- People at risk for known founder mutations in certain ethnic groups
In current practice, testing is done as a multi-gene panel rather than a single gene (in addition to BRCA1/2, genes such as PALB2, CHEK2, ATM, TP53).
What does a positive result mean?
- Surveillance: intensive follow-up starting at an earlier age, with annual mammography and MRI.
- Surgical choice: if you have a breast cancer diagnosis, options that include risk-reducing surgery on the other breast are discussed.
- Risk-reducing surgeries: removal of the breasts and ovaries/tubes lowers risks considerably; timing is planned individually.
- Treatment: in some patients with a BRCA change, targeted drugs such as PARP inhibitors can be an option.
- Family: testing is offered to first-degree relatives (cascade testing).
Counselling before and after the test
Because the result concerns not only the person but also the family, genetic counselling before and after the test is important. Discussing the scope of the test, its possible results (positive, negative, uncertain) and their emotional impact in advance makes decision-making easier.
Doç. Dr. Ebru Şen
General surgeon whose area of interest is breast surgery. Sees patients at Istinye University Medical Park Gaziosmanpaşa Hospital and Başakşehir Çam and Sakura City Hospital.
