Caroline was a 31-year-old who came to the surgery for a routine pill check. She was nulliparous though was considering pregnancy in the next two years.
She was a non-smoker with a normal BMI and no risk factors for cardiovascular disease.
When asked about family history Caroline said her mother had been diagnosed with breast cancer at 35 and her aunt was diagnosed at 45 years. She was not aware of a family history of ovarian, prostate or colon cancers.
Following a discussion about the role of BRCA gene mutations in breast and ovarian cancers, Caroline decided to discuss this with other family members, particularly her mother. I also stressed the importance of being 'breast aware'.
A few months later, Caroline and her mother attended the surgery to request a referral to the clinical genetics department. Following extensive counselling, Caroline's mother was initially tested for BRCA 1 and 2 genes and found to be positive for BRCA 1 mutation. Afterwards, Caroline was offered testing and was also found to be positive for BRCA 1 mutation.
Caroline had further counselling to come to terms with the implications of the result. She also had a discussion about the protective effect of the combined oral contraceptive pill against ovarian cancer versus a possible increased risk of breast cancer.
She decided to stop using the combined pill and was offered yearly MRI breast screening. She is now 19 weeks pregnant.
Inherited breast cancer
Inherited gene mutations only account for around 5 per cent of all breast cancers. The main genes involved are BRCA 1 and 2. These are known as tumour suppressor genes and mutations of these have been linked with hereditary breast, ovarian and fallopian tube cancers.
These also cause an increased risk of many other cancers, such as prostate, pancreas and colon cancer.
A mutated BRCA gene usually makes non-functional proteins which are unable to act as tumour suppressor agents.
In the general population, the lifetime risk of breast cancer is around 11 per cent. In a woman with a BRCA gene mutation there is a 50-80 per cent risk of developing breast cancer and 15-40 per cent lifetime risk of ovarian cancer.
It is likely that these mutations run in a family if there is history of early breast cancers in multiple family members, bilateral breast, ovarian and other cancers.
Genetic counselling and risk assessment is carried out initially to establish the level of risk, which can be classed as that of the general population, raised or very high.
Genetic testing is offered when individuals are found to be at raised or high risk of having the mutation.
It is preferable to carry out predictive testing where a blood sample can be taken from a family member affected with cancer. If a mutation is found, other family members are tested for the same mutation.
However, if no initial gene fault is discovered, then this still leaves the possibility of an unidentified gene mutation.
The field of genetic screening raises many ethical issues, such as confidentiality, privacy and 'meddling' with nature. Family members may not wish to share their genetic information with their relatives.
Surveillance is offered to those at increased risk through yearly mammograms or MRI scans, CA-125 tests and transvaginal scans.
There should also be a discussion about risk reduction through lifestyle measures, such as preventing obesity and encouraging breast feeding. For a few, prophylactic surgery would be an option. In Caroline's case genetic testing perhaps hastened her decision to start a family.
- Dr Aziz is a GP in Bristol
NICE. Familial breast cancer: The classification and care of women at risk of familial breast cancer in primary, secondary and tertiary care. CG41. London, NICE, 2006. http://guidance.nice.org.uk/CG41