The implications of BRCA gene mutation
People who inherit BRCA gene mutations are at an increased risk of developing breast cancer and ovarian cancer compared with the general population. If a faulty BRCA gene is found it is possible to benefit from measures for prevention and early detection of these cancers.
We all have BRCA1 and BRCA2 genes in our bodies. However, in some people, the BRCA gene is mutated (changed) and this happens when the DNA that makes up the gene becomes damaged. This means it may no longer be effective at repairing broken pieces of DNA and helping to prevent ovarian or breast cancer.
Genetic testing to check for a BRCA mutation initially involves genetic counselling with a clinical geneticist followed by a blood or sputum test. Genetic counselling will involve discussing the potential risks, limitations and benefits of receiving genetic testing.
Currently, genetic testing is only recommended in people with a high risk of carrying BRCA, which often are patients diagnosed with breast or ovarian cancer or people with a family history of BRCA or related cancers.
Breast Cancer Network Australia estimates that BRCA1 or BRCA2 mutations occur in about 1 in 400 Australian women. Men with BRCA mutations have a higher risk of developing breast and prostate cancers.
What does it mean if you are diagnosed with a BRCA mutation?
- The increased risk of ovarian cancer is estimated to be about 40-60%.
- Breast cancer risk is increased in the range of 30-60%.
- In women, an increased risk is also observed for fallopian tube cancer and primary peritoneal cancer, both of which start in the same cells as ovarian cancer.
- A person with a cancer-predisposing gene fault has a 50% chance of passing on the faulty gene to their biological child. A biological sibling also has a 50% chance of carrying that gene.
- A woman with one of these mutations is more likely to be diagnosed with these cancers at a younger age.
If you have a BRCA mutation, regular breast cancer screening is important (ultrasound, MRI). Patients also have the option of prophylactic surgery (mastectomy).
Unfortunately, managing the increased risk of ovarian cancer is not as simple as with breast cancer because screening for ovarian cancer is inaccurate due to a lack of reliable tests. The oral contraceptive pill may be prescribed as it reduces ovarian cancer risk by 50%.
Risk-reducing prophylactic surgery is the most effective option and is >95% effective in reducing a person’s ovarian cancer risk (removing the ovaries and fallopian tubes).
Even though prophylactic surgery lowers a BRCA positive patients risk significantly, it still does not completely eliminate the risk because it does not guarantee that cancer will not develop, as not all at-risk tissue can be removed by these procedures. This is why these procedures are described as “risk-reducing”.
Risk-reducing prophylactic surgery to remove the ovaries also reduces the risk of breast cancer in premenopausal women significantly. The earlier the ovaries are removed, the higher the protection against breast cancer.
Read more about risk-reducing prophylactic surgery to remove the ovaries here.
Read my article about ovarian cancer survival in BRCA-positive patients here.
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