Beyond BRCA1 & BRCA2: U.K. Researchers Identify Genetic Defect That Could Increase Risk of Ovarian Cancer Up To 40%

Scientists have located a region of DNA which – when altered – can increase the risk of ovarian cancer according to research published in Nature Genetics today. An international research group led by scientists based at the Cancer Research UK Genetic Epidemiology Unit, at the University of Cambridge and UCL (University College London) searched through the genomes of 1,810 women with ovarian cancer and 2,535 women without the disease from across the UK. …The scientists estimate that there is a 40 per cent increase in lifetime risk for women carrying the DNA variation on both copies of chromosome nine compared with someone who doesn’t carry it on either chromosome. The risk for women carrying the variation on both chromosomes is 14 in 1000 – compared with [10] ten in 1000 [in the general population]. … The lifetime risk for a woman carrying the DNA variant on one copy of the chromosome is increased by 20 per cent from ten in 1000 to 12 in 1000. …

Genetic link to ovarian cancer found

Cancer Research UK

SUNDAY 2 AUGUST 2009

Cancer Research UK Press Release

Scientists have located a region of DNA which – when altered – can increase the risk of ovarian cancer according to research published in Nature Genetics today.

An international research group led by scientists based at the Cancer Research UK Genetic Epidemiology Unit, at the University of Cambridge and UCL (University College London) searched through the genomes of 1,810 women with ovarian cancer and 2,535 women without the disease from across the UK. They analysed 2.5 million variations in DNA base pairs – the letters which spell out the genetic code – to identify common spelling ‘errors’ linked to ovarian cancer risk.

The scientists identified the genetic ‘letters’- called single nucleotide polymorphisms (SNPs) – which when spelled slightly differently increase ovarian cancer risk in some women. This is the first time scientists have found a SNP linked uniquely to risk of ovarian cancer and is the result of eight years of investigations. With the help of the international Ovarian Cancer Association Consortium (OCAC), they then looked at more than 7,000 additional women with ovarian cancer and 10,000 women without disease from around the world to confirm this finding.

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The region of risk DNA is located on chromosome nine – there are 23 pairs of each chromosome in humans, one of each pair inherited from each parent. The scientists estimate that there is a 40 per cent increase in lifetime risk for women carrying the DNA variation on both copies of chromosome nine compared with someone who doesn’t carry it on either chromosome. The risk for women carrying the variation on both chromosomes is 14 in 1000 – compared with [10] ten in 1000 [in the general population].

Approximately 15 per cent of women in the UK population carry two copies of the variant DNA.

The lifetime risk for a woman carrying the DNA variant on one copy of the chromosome is increased by 20 per cent from ten in 1000 to 12 in 1000. Approximately 40 per cent of women in the UK carry one copy.

Senior author Dr. Simon Gayther, whose work is supported by Cancer Research UK and The Eve Appeal charity which fundraises for the gynaecological cancer research team based at UCL, said: “The human DNA blueprint contains more than 10 million genetic variants. These are part and parcel of our characteristics and make-up – but a handful will also increase the chances of some women getting ovarian cancer and we have found the first one of these.”

“There is now a genuine hope that as we find more, we can start to identify the women at greatest risk and this could help doctors to diagnose the disease earlier when treatment has a better chance of being successful.”

Dr. Andrew Berchuck, head of the international Ovarian Cancer Association Consortium steering committee, said: “This study confirms that ovarian cancer risk is partly determined by genetic variants present in a large number of women. This initial discovery and others that will likely follow in the future lay the groundwork for individualised early detection and prevention approaches to reduce deaths from ovarian cancer.”

Ovarian cancer is the fifth most common cancer in women in the UK with around 6,800 new cases diagnosed each year in the UK – 130 women every week. It is the fourth most common cause of cancer death in women in the UK with around 4,300 deaths from the disease in the UK each year.

BRCA1 and BRCA2 are high risk genes which cause breast cancer and are already known to significantly increase the risk of ovarian cancer- but faults in these genes are rare and probably cause less than five per cent of all cases of ovarian cancer.

Lead author, Professor Dr Paul Pharoah, a Cancer Research UK senior research fellow at the University of Cambridge, said: “We already know that people with mistakes in the BRCA1 and BRAC2 genes have a greater risk of ovarian cancer – but on their own they don’t account for all of the inherited risk of the disease. “It is likely that the remaining risk is due to a combination of several unidentified genes – which individually carry a low to moderate risk. Now we have ticked one off, the hunt is on to find the rest.”

Rose Lammy, the mother of David Lammy MP [Member of Parliament] for Tottenham and Minister for Higher Education and Intellectual Property, died of ovarian cancer in 2008. Rose Lammy’s DNA sample was included in the study, and she carried both risk alleles of the new genetic marker that researchers have identified.

David Lammy said: “I am pleased that Mum’s sample was included in this study as it is one step towards earlier diagnosis of ovarian cancer when treatment is more successful. We now know the fact that she had this altered DNA meant that her lifetime risk had risen from 10 in 1,000 to 14 in 1,000, an increase of 40 per cent compared to those women who don’t carry this DNA variation. Dr Lesley Walker, director of cancer information at Cancer Research UK, added: “This is an important discovery. Our researchers have worked as part of a huge collaboration to establish the regions of DNA that can increase someone’s risk of developing ovarian cancer. “This research paves the way for scientists to discover even more genes linked to ovarian cancer and could lead to new approaches to treat or prevent the disease – crucially it will help doctors manage women who are at increased risk.”

Source: Genetic link to ovarian cancer found, Cancer Research U.K. Press Release & Video, 02 Aug. 09.

Reference: Honglin Song et al. (2009). A genome-wide association study identifies a new ovarian cancer susceptibility locus on 9p22.2 Nature Genetics 10.1038/ng.424.

Ovarian Cancers Detected Early May Be Less Aggressive

“The biology of ovarian cancers discovered at an early stage may render them slower growing and less likely to spread than more aggressive cancers, which typically are discovered in an advanced stage, according to a study led by investigators in the Duke Comprehensive Cancer Center.  This finding has implications for the question of whether screening for ovarian cancer could save lives. …”

“The biology of ovarian cancers discovered at an early stage may render them slower growing and less likely to spread than more aggressive cancers, which typically are discovered in an advanced stage, according to a study led by investigators in the Duke Comprehensive Cancer Center.  This finding has implications for the question of whether screening for ovarian cancer could save lives.

berchuck-andrew

Dr. Andrew Berchuck is Director of the Duke Division of Gynecologic Oncology, Duke Comprehensive Cancer Center, Durham, North Carolina

‘Our study showed that the ovarian cancers currently detected at an early stage have gene expression profiles that correlate with favorable outcome, rather than being representative of the entire spectrum of disease aggressiveness,’ said Andrew Berchuck, MD, a gynecologic oncologist at Duke and lead investigator on this study.  ‘This highlights the potential challenges of developing a screening test for this disease, because earlier detection of aggressive cases is essential if screening is to reduce ovarian cancer deaths.’

The results of this study and the implications for screening as an approach to decreasing mortality parallel the challenges seen in lung cancer and prostate cancer.  In those cancers, while screening approaches based on radiological imaging and/or blood markers detect cancers, it remains unclear whether cancer-related deaths are prevented because screening preferentially detects more benign cancers that are much less likely to be fatal, Berchuck said.

‘While these results could be seen as discouraging, it must be remembered that this information is an important piece of the ovarian cancer puzzle, and data like these that increase our understanding of the disease hopefully will eventually lead to breakthroughs in prevention, early detection and treatment of this deadly disease,’ Berchuck said.  Although there is currently no approved ovarian cancer screening test for the general population, the CA125 blood test and transvaginal ultrasound imaging currently are being evaluated in clinical trials.

The researchers looked at gene expression patterns in 166 ovarian cancer tissue samples taken from patients who were treated at Duke, H. Lee Moffitt Cancer Center, and Memorial Sloan-Kettering Cancer Center and from the Gynecologic Oncology Group Tumor Bank.  For this study, researchers examined samples of advanced ovarian cancers from patients who had experienced long-term survival — over seven years — and patients who had done extremely poorly, and died within three years of diagnosis.  The researchers used microarrays — a method for examining thousands of snippets of DNA — with about 22,000 probe sets to examine patterns of gene expression among the samples, and identified genes that were most predictive of survival.

‘We found that certain patterns predicted long-term survival and others predicted a poorer prognosis in advanced stage cases,’ Berchuck said. ‘Cancers that were detected at an early stage almost always shared gene expression characteristics with advanced stage cases that were long-term survivors, suggesting a shared favorable biology.’

The researchers published their results in the March 24, 2009, issue of the journal Clinical Cancer Research. The study was funded by the Gail Parkins Ovarian Cancer Research Fund and the National Institutes of Health.

Other researchers involved in this study include Edwin Iversen, Jingqin Luo, Jennifer Clarke, Hisani Horne, Angeles Secord, Jason Barnett, Susan Murphy, Holly Dressman, Jeffrey Marks of Duke; Douglas Levine and Jeff Boyd of Memorial Sloan-Kettering Cancer Center in New York City, NY; Miguel Alonso of the Universidad Autonoma de Madrid; and Johnathan Lancaster of H. Lee Moffitt Cancer Center and Research Institute.”

Primary SourceSpotlight:  Ovarian Cancers Detected Early May Be Less Aggressive, News Article, Duke Comprehensive Cancer Center, March 23, 2009.