Genetic profiling for breast cancer on the horizon
WEDNESDAY 25 JUNE 2008
Cancer Research UK scientists have shown that it may soon be possible to offer women a genetic test to assess their risk of breast cancer which could aid early diagnosis for those at high risk of the disease. Their findings are revealed in the New England Journal of Medicine* today (Wednesday).
Cancer Research UK funded scientists from the University of Cambridge, looked at the seven common 'modest risk' gene sites** which, in combination, put women at increased risk of developing breast cancer. They wanted to see what impact testing women for these genes might have on future public health policy – such as lowering or increasing the age at which they start to be screened for breast cancer and targeting lifestyle advice to women to reduce their risk of developing the disease.
Study author Dr Paul Pharoah, from the University of Cambridge, said: "We are a few years away from a new and powerful range of genetic tests for breast cancer. We believe genetic testing has the potential to enable doctors to identify a woman at an increased risk of breast cancer who would benefit from mammography at an early age or woman who may benefit from regular MRI scanning as well. This approach would also identify a 55 year old woman with a low chance of breast cancer who possibly wouldn’t need such regular checks."
Currently doctors only test women who have a very strong family history of breast cancer for the high risk breast cancer genes such as BRCA1, BRCA2, PTEN, and TP53. But these gene faults are rare and few women in the general population will benefit from such testing. In contrast, genes that give woman a slightly increased risk are common and although each one has little impact alone, testing for their combination could prove useful.
Lead author Professor Sir Bruce Ponder, director of Cancer Research UK's Cambridge Research Institute at the University of Cambridge, said: "It is very exciting to see workable and affordable approaches to genetic screening for breast cancer on the horizon. We expect such technology to develop very fast in the next decade so it's important that we start thinking about how best to apply these advances."
Dr Lesley Walker, director of cancer information at Cancer Research UK, said: "This study marks the potential for a tailor-made approach to screening for breast cancer which could radically change who we target and how we detect early signs of the disease. Great progress has been made to improve our understanding of the ways in which certain genes affect the risk of breast cancer - and as scientists find even more of these 'risk genes', our ability to use genetic tests to identify woman at risk will improve. But there is still some way to go before this kind of profiling becomes a reality."
ENDS
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Notes to Editors
*Polygenes, Risk Prediction, and Targeted Prevention of Breast Cancer (2008), Paul Pharoah et al, the New England Journal of Medicine.
Breast cancer is now the most common cancer in the UK. Each year more than 44,000 women are diagnosed with breast cancer, that’s more than 100 women a day.
Rare, high-risk genes
BRCA1, BRCA2 – out of every 100 women with a faulty copy of one of these genes, between 50 and 85 will develop breast cancer at some point in their lives (50-85 per cent lifetime risk). Tests for these genes are available to women with cancer and their families if a history of several breast and/or ovarian cancers run in the family.
TP53, PTEN – these genes are rare compared to BRCA1 and BRCA2 but tests are also available for these genes in genetics clinics.
Genes with rare, modest-risk variants
**CHEK2, ATM, BRIP1, PALB2 – less than one per cent of the population carry a risk-associated version of one of these genes. Not all women with these genetic variants will go on to develop breast cancer but researchers believe these particular genetic faults each contribute to around 100 cases of breast cancer diagnosed in the UK each year. Tests for these genetic variants are not routinely used in clinical practice.
- The following genes have variants that are common in the population and are associated with a slight increase in risk of breast cancer.
- CASP8 – around three quarters of women carry two copies of the version of this gene that is associated with an increased risk of breast cancer.
- FGFR2 – around one in six women carries two copies of the version of this gene that is associated with an increased risk of breast cancer.
- TNRCP, MAP3K1, LSP1 - these genes were all located close to the regions where the researchers identified genetic variations but other genes in the same regions my be important
- TNRC9 – around one in 16 women carries two copies of the version of this gene that is associated with an increased risk of breast cancer.
- MAP3K1 – around one in 13 women carries two copies of the version of this gene that is associated with an increased risk of breast cancer.
- LSP1 – around one in 11 women carries two copies of the version of this gene that is associated with an increased risk of breast cancer.
- 8q region – the researchers think that a gene exists close to this region that contributes to breast cancer risk but they haven’t isolated a specific gene yet.
Genetic predisposition to cancer
Some people are born with a fault in one of their genes. This does not mean that they will definitely develop cancer, but it does mean that fewer other things need to go wrong for disease to develop. Doctors say people with a fault in certain genes are more likely to get cancer or have a genetic predisposition to the disease.
Women who have a very strong family history may have a faulty gene or genes in their family that increases their risk of breast cancer. There are number of faulty genes that have been shown to increase breast cancer risk. But, so far, doctors only test for four genes BRCA1, BRCA2, TP53 and PTEN, as these are associated with high risks of developing cancer.
Cancer Research UK has funded a series of genome-wide studies in breast and other cancers. Find out more about this work here.
Anyone affected by cancer can contact Cancer Research UK's cancer information nurses on 0808 800 4040 (freephone) or visit the charity's patient information website CancerHelp UK.
About the University of Cambridge
The University of Cambridge's reputation for excellence is known worldwide and reflects the scholastic achievements of its academics and students, as well as the world-class original research carried out by its staff. Some of the world’s most significant scientific breakthroughs have occurred at the University, including the splitting of the atom, invention of the jet engine and the discoveries of stem cells, plate tectonics, pulsars and the structure of DNA. From Isaac Newton to Stephen Hawking, the University has nurtured some of history's greatest minds and has produced more Nobel Prize winners than any other UK institution with over 80 laureates.
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