An international consortium – including scientists from KU Leuven, VIB and University Hospitals Leuven – has identified more than 80 regions in our DNA that increase the risk of developing breast, prostate and ovarian cancer. The study involved scientists from 40 countries and compared the DNA of 100,000 cancer patients and 100,000 healthy individuals. It is the first time that a study of this kind has been performed on such a large scale.
“The results demonstrate how complex cancer is,” said Diether Lambrechts, who coordinated the Belgian portion of the study. “Hundreds of genes play a role in the development of cancer. Understanding why some people have a greater risk of cancer than others is very important. It opens up perspectives to reduce their risks in the future or to attack the disease at the earliest stage, thus increasing patients' chances of survival.”
SNPs
Consortium scientists searched for genetic variations – so-called ‘single nucleotide polymorphisms (SNPs)’ – that result in an increased risk of cancer. They compared the DNA of 100,000 cancer patients to the DNA of 100,000 healthy individuals and identified SNPs that were more common in people with prostate, breast or ovarian cancer. A single SNP results in a minimal increase in cancer risk, but people with many high-risk SNPs have a significantly increased risk of prostate or breast cancer, researchers found.
Many of the newly identified high-risk SNPs are located in DNA regions that control for gene behaviour. These SNPs can disrupt cell control and can thereby override the ‘brake signals’ that stop cell growth. Further research into how these genes are involved in cancer is crucial to gaining a better understanding of cancer growth and finding new insights into cancer treatments.
The scientists found 49 SNPs that increase the risk of breast cancer. Some of these SNPs are located in regions that are also involved in other cancers. This indicates that they could affect a more general mechanism in the development of cancer. 9 new SNPs were identified for ovarian cancer. 26 new SNPs were identified for prostate cancer.
Estimating risk
The consortium also examined the extent to which certain SNPs affect the risk of cancer in people with errors in the known BRCA breast cancer genes. Women with a mutation in a BRCA gene have an increased risk of developing breast or ovarian cancer. However, it is not yet clear what leads to the actual development of the cancer. The scientists discovered that women with BRCA mutations and certain SNPs are almost certain to develop breast cancer before they turn 80. Further research should result in much better screening techniques.
Of the 26 new SNPs identified for prostate cancer, 20 are associated with the disease in its most aggressive and life-threatening form. This new information will allow scientists to set up tests to identify men with a very high risk of prostate cancer. By screening this group at very regular intervals, the number of men that die as a result of prostate cancer – currently 1 in 6 prostate cancer patients – could be significantly reduced. The plan is to use this new information to optimise tests for prostate cancer with the aid of genetic screening. In the long term, a similar approach can also be implemented to more accurately predict breast cancer.
Unprecedented collaboration
The results of the study are being published simultaneously in 12 scientific articles in various leading journals, including Nature Genetics, Nature Communications and The American Journal of Human Genetics. This is exceptional and indicates the importance of the findings.
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