Cancer Research UK scientists have developed a computer programme that can predict genetic susceptibility to breast and ovarian cancer with unprecedented accuracy.
‘BOADICEA’ 1 uses detailed family history to predict a woman’s risk of developing cancer. It improves on previous programmes because it takes into account genetic mutations besides those of the well-known BRCA1 and BRCA2 genes.
The researchers plan to offer BOADICEA to health professionals to help them pre-select women likely to be at high risk for further testing – and sparing others the anxiety of waiting for genetic test results. The programme is described in the British Journal of Cancer2.
Women with a strong risk of breast and ovarian cancer can be offered pre-emptive measures such as screening from an early age, preventative surgery (removing breasts or ovaries) or chemoprevention using drugs such as tamoxifen.
But the genetic tests needed to identify women as having genetic mutations in genes such as BRCA1 and BRCA2 are expensive. They can also be slow, causing considerable anxiety in the many patients who turn out not to be at high risk.
Professor Doug Easton of the Cancer Research UK Genetic Epidemiology Unit in Cambridge says: “We created the BOADICEA programme in order to better target genetic testing towards only those women who are most likely to carry the mutations.
“BOADICEA works out a woman’s breast and ovarian cancer risk using detailed information on her family history of cancer. The programme calculates both her risk of carrying a particular cancer-causing mutation, and her overall risk of developing breast or ovarian cancer.”
The programme predicts cancer risk based on detailed genetic data gathered on 1484 women with breast cancer and 156 families with multiple breast and ovarian cancer cases.
The team has just finished testing the programme’s accuracy by using it to predict high genetic risk of breast cancer in women whose family history was collected in the past by doctors.
Comparing BOADICEA’s answers to the results of genetic tests in those women has confirmed the programme’s strength.
Many genes are responsible for a woman’s inherited risk of breast cancer. Most of these genes have only a small effect on their own, but working together they are a strong influence.
The detailed family data the team have used to put BOADICEA together means the programme can take the influence of all of these genes into account – even those genes for which there is no biological test.
Professor Easton adds: “BRCA1 and BRCA2 together account for under 20 per cent of breast cancer clusters in families, so for a computer programme of this nature to be accurate it is vital it can take other mutations into account.
“Having put the finished product through its paces by rigorously testing it, we have confirmed that it is more accurate than any such programme created in the past.”
The team is currently making BOADICEA more ‘user friendly’ and plans to make it available via the web to oncologists and geneticists.
Professor Robert Souhami, Director of Policy and Communication at Cancer Research UK, says: “We are very pleased to support the development of this important computer programme.
“It holds the promise to be the most accurate computer-based programme available to identify women at high risk of breast and ovarian cancer on account of gene mutations in their families.
“Women found to be at high risk of getting cancer can explore opportunities with their doctor to reduce the chances of the cancer developing or to detect it at a very early stage through regular monitoring.”
- Breast and Ovarian Analysis of Disease Incidence and Carrier Estimation Algorithm
- British Journal of Cancer91 (8) Read the report
The next step in this project is to increase BOADICEA’s power by making it possible to input information on women’s non-genetic risk factors, such as breast-feeding, age at menopause and the number of children she has had.
Parallel studies are underway to calculate the effects such non-genetic factors have on cancer risk in women with and without mutations in BRCA1 and BRCA2 genes. This detailed information will enhance BOADICEA’s accuracy.
BOADICEA registers a woman’s age, as the risk of cancer caused by different genes peaks at different ages.
The programme is based on data from a UK population, so if used further afield it would need to be adjusted to take account of varying incidence of BRCA gene mutations. For example, BRCA gene mutations are more common among Icelanders and Ashkenazi Jews than in the UK population.
The team plans to trial BOADICEA in several thousand women visiting UK cancer genetics clinics.
Women who inherit a damaged BRCA1 gene have a 60-85 per cent chance of developing breast cancer at some stage in their lives and a 20-40 per cent chance of developing ovarian cancer. For BRCA2, the risks are 40-60 per cent and 10-20 per cent respectively.
Around 1 in 1,000 women in the UK carry a damaged version of the BRCA1 gene and 1 in 700 carry a faulty BRCA2 gene.
Over 80% of families with four or more cases of breast or ovarian cancer under the age of 60 are found to have a damaged version of BRCA1 or BRCA2.
Faulty BRCA1 and BRCA2 genes are present in fewer families with less than 4 cases of breast or ovarian cancer and overall account for less than 5% of all breast cancer cases.
Visit the CancerHelp UK website for clear, easy to understand information about cancer and cancer treatments.
Follow the five-point breast aware code:
- know what is normal for you
- look and feel
- know what changes to look for
- report any changes without delay
- go for breast screenings if you are 50 or over
Look out for these warning signs of breast cancer:
- changes in the shape, appearance or feel of your breasts
- a lump in one breast or armpit which is different from the other side or is new
- any puckering or dimpling of the skin
- nipple discharge, a rash or a change in nipple position
- pain or discomfort in one breast that is different from normal
Report any of these changes to your doctor without delay. Such changes may have other causes but should always be investigated.
Breast cancer affects around 40,470 women each year in the UK.
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