Sarah Beck, a Registered Genetic Counsellor at Check4Cancer, answers your questions about the risks of inheriting and the benefits of testing for BRCA1 or BRCA2 gene variants.

What is breast cancer genetic testing?

Breast cancer affects around 1 in every seven women in the general population, but less than 10% of all breast cancers are ‘genetic’ and caused by an inherited genetic predisposition or faulty gene.

Genetic testing can be carried out to identify if a person has an inherited genetic predisposition to developing breast cancer, and this involves reading through specific genes looking for spelling mistakes or ‘variants’ that stop the gene from working.

What are the BRCA1 and BRCA2 genes?

Inside our cells, we have approximately 25,000 genes which code for different proteins.  All our genes come in pairs, and we inherit one copy of each gene pair from each of our parents. The BRCA1 and BRCA2 genes are genes that we all have, and these genes code for proteins called tumour suppressors. This means that the BRCA1 and BRCA2 genes actually stop cancer from developing.  If there is a spelling mistake/variant/mutation in the BRCA1 or BRCA2 genes, the gene doesn’t function properly, and this results in an increased risk of developing cancer.

What are the red flags you should look out for in your family history which might suggest a hereditary link?

Family history, age and breast cancer type (histology) are all important when assessing whether or not a genetic predisposition may have caused a breast cancer.

If there are more cases of breast cancer in your family than you would expect to see by chance, if there is a pattern of breast, ovarian and prostate cancers, or if family members are developing these cancers at young ages, you should seek a genetic assessment. Male breast cancers and triple-negative breast cancers under the age of 60 are also suggestive of a genetic predisposition.

Who is at risk of having the faulty BRCA gene in a family?

If a pathogenic gene variant is identified in a family member, their parents, siblings and children will each have a 50% chance of having the same variant.  Aunts, uncles, nieces and nephews will have a 25% chance, and cousins will have a 12.5% chance.

How much does a variant in BRCA1 and BRCA2 increase a woman’s lifetime risk (up to the age of 80) of developing breast and ovarian cancer?

Men and BRCA genes: what do men need to know?

Variants in the BRCA1 and BRCA2 genes also increase the risk of developing prostate cancer, and variants in the BRCA2 gene are also associated with an increased risk of developing male breast cancer.

Who should consider genetic counselling and testing for BRCA1 and BRCA2 variants?

If you have any of the following diagnoses or family histories, you should consider genetic counselling and testing for faulty BRCA genes:

• Invasive breast cancer < 40 years
• Bilateral breast cancer, both < 50 years
• Triple negative breast cancer < 60 years
• Male breast cancer at any age
• Non-mucinous ovarian cancer at any age
• Breast cancer < 45 years and a first-degree relative with breast cancer < 45 years
• Three or four close relatives with breast cancer at any age
• Ashkenazi Jewish ancestry and breast cancer at any age

What are the benefits of genetic testing for BRCA1 and BRCA2 variants?

If a variant is identified in BRCA1 or BRCA2, this will enable appropriate cancer risk management and may affect cancer treatment options. 

If a gene variant is identified, other family members can then be tested to determine their own risks of developing cancer.  In turn, this will allow them to manage their own cancer risks accordingly.

If the results are normal, this would provide reassurance.

If I have a BRCA1 or BRCA2 gene variant, what can be done about it?

Females who have a variant in BRCA1 or BRCA2 will be offered additional breast screening from the age of 30 and possibly from the age of 25, depending on their family history.  Males will be offered additional prostate screening from the age of 40. 

Alternatively, females may choose to have a risk-reducing mastectomy and oophorectomy to reduce their risks of developing breast and ovarian cancer.

For more information of Check4Cancer's Genetic Counselling Service please click here.