Thursday January 21 2016
Around 10% of ovarian cancers may be the result of a faulty gene
"A faulty gene has been identified that increases the risk of ovarian cancer more than threefold," The Independent reports. The genetic mutation, found in the BRIP1 gene, adds to the known genetic warning signs for ovarian cancer.
Exactly what causes ovarian cancer is not known, but around 10% of ovarian cancers are thought to be the result of a faulty gene. However, previous research has shown defects in the BRCA1 and BRCA2 genes increase the risk of both ovarian and breast cancer.
In this study, the researchers looked at whether defects in genes associated with the repair of BRCA1 or BRCA2 DNA also increase the risk of ovarian cancer. The researchers used data from women with and without cancer to test for defects in a few different genes.
Based on the resulting data, they estimated the risk of ovarian cancer for women with the BRIP1 mutation was 3.4 times greater than that of the UK general population.
To put that figure in a wider context, 58 out of every 1,000 women with the BRIP1 gene mutation would be expected to develop the condition.
These findings are of interest, and provide a route for further research in the area to understand more about the possible causes of ovarian cancer – and hopefully lead to better prevention and treatment strategies.
Where did the story come from?
The study was carried out by researchers from a number of institutions, including the University of Southern California and the University of Cambridge.
Funding was provided by Cancer Councils across Australia, Cancer Research UK, the Eve Appeal (The Oak Foundation), the Fred C. and Katherine B. Andersen Foundation, the US National Institutes for Health, the National Health & Medical Research Council of Australia, Cancer Australia, Roswell Park Cancer Institute Alliance Foundation, the UK Department of Health, the UK National Institute for Health Research, and the US Army Medical Research and Materiel Command.
It was published in the peer-reviewed Journal of the National Cancer Institute.
The study was actually made public in 2015. It seems the charity Cancer Research UK has successfully tried to make the findings headline news, as the study received very little publicity when it was first released.
The UK media has largely reported on the study accurately, with quotes from the study authors explaining the potential importance of these findings.
The Independent usefully puts the increased risk associated with the BRIP1 gene mutation into a wider context that most people can understand.
Simply reporting that the mutation "increases the risk of ovarian cancer threefold" means little to people if they don't know what the overall baseline risk is.
However, The Daily Telegraph overstated the findings by stating that, "Screening could prevent one in five ovarian cancer deaths".
The researchers clearly stated larger studies are required to confirm the results before this gene is used to inform clinical decision making.
What kind of research was this?
This modelling study aimed to assess whether a mutation shortening BARD1, BRIP1, NBN and PALB2 genes are associated with an increased risk of ovarian cancer in populations of European origin. It is thought such mutations could stop cells repairing their DNA, leading to cancer.
Defects in the genes BRAC1 and BRAC2 are already known to increase the risk of cancer. It's thought the mutations studied here may prevent these two genes repairing DNA, though this theory is in the early stages of research.
What did the research involve?
This study used data from a number of case control studies, one ovarian cancer registry, one case series, and women from the UK Familial Ovarian Cancer Screening Study (UKFOCSS).
The UKFOCSS included women over the age of 35 with a lifetime risk of at least 10% based on their family history.
Statistical methods were used to test for an association between the risk of ovarian cancer and the presence of the mutation in each gene.
What were the basic results?
Results were available for 3,236 participants with ovarian cancer and 3,341 women without cancer. Any of these genetic mutations were found in 1.6% of women in the ovarian cancer group, compared with 0.5% in the control group.
When looking at each gene separately, a higher number of BRIP1 mutations were found in participants with ovarian cancer (0.92%) than without (0.09%). However, no differences were observed between groups for BARD1, NBN1 or PALB2 genes.
The presence of the mutations was evaluated further using the UKFOCSS, with some similar findings. Genetic mutations were significantly higher for those with ovarian cancer than those without for BRIP1 and PALB2, but there were no significant differences between groups for BARD1 or NBN.
The risk of ovarian cancer for women with the BRIP1 mutation was estimated to be 3.4 times greater than that of the UK general population using data from a number of case control studies.
How did the researchers interpret the results?
The researchers concluded that, "Deleterious germline mutations in BRIP1 are associated with a moderate increase in EOC [epithelial ovarian cancer] risk.
"These data have clinical implications for risk prediction and prevention approaches for ovarian cancer, and emphasise the critical need for risk estimates based on very large sample sizes before genes of moderate penetrance have clinical utility in cancer prevention."
This study was designed to assess whether a mutation that shortens the BARD1, BRIP1, NBN and PALB2 genes is associated with an increased risk of ovarian cancer in women of European origin.
The cause of ovarian cancer is not known, but certain factors are known to increase risk, including age, the number of eggs the ovaries release, and whether someone in your family has had ovarian or breast cancer in the past.
Genetic mutations are thought to be the cause of 10% of ovarian cancers. Screening is only available for women who are at a high risk of developing the condition because of a strong family history or inheritance of a particular faulty gene.
The researchers believe this particular type of genetic mutation stops cells repairing their DNA, and this could then lead to cancer.
Participants with ovarian cancer were found to have a higher number of mutations in the BRIP1 gene. This difference was not seen for the other genes tested, however.
This study has some limitations, which the authors do acknowledge. The prevalence of the mutation may have been underestimated, as sequencing coverage was less than 100% for each gene in all samples.
The researchers were not able to detect all mutations using their strategy. And the number of women with the genetic defect in the sample was very small.
These findings are of interest, and provide a route for more research in the area to understand more about the possible causes of ovarian cancer.
There are a number of ways you can reduce your risk of ovarian cancer, including staying a healthy weight.
Anything that stops the process of ovulation can also help minimise your chances of developing ovarian cancer. This includes:
- being pregnant
- taking the contraceptive pill
- having a hysterectomy
If you have a strong family history of ovarian cancer, you may also wish to talk to your GP about the screening for genes associated with the condition.