Cancer Research UK funded scientists have discovered that women who carry a faulty copy of a gene called RAD51D have almost a one in 11 chance of developing ovarian cancer, the most significant ovarian cancer gene discovery for more than a decade.

The team at The Institute of Cancer Research (ICR) examined DNA from women from 911 families with ovarian and breast cancer and compared differences in DNA with a control group of 1060 people from the general population.

The team discovered eight gene faults in the RAD51D gene in women with cancer, compared with one in the control group.

Ovarian cancer is the fifth most common cancer in women - around 6,500 cases are diagnosed annually in the UK. The researchers estimate that RAD51D gene faults are present in almost one per cent of women with ovarian cancer - around 50 UK women each year.

Around one woman in 70 in the general population is at risk of developing ovarian cancer, but for those with a RAD51D gene fault this risk is increased to one in 11 – making these women six times more likely to develop the disease.

The RAD51D gene is important for repairing damaged DNA. When the RAD51D gene is faulty, a key repair pathway fails. This means DNA damage is not fixed and DNA faults build up in cells which make them more likely to turn into cancer.

The team also showed that cells with faulty RAD51D can be selectively destroyed by a relatively new class of cancer drugs called PARP inhibitors. These drugs are showing great promise in clinical trials for the treatment of breast and ovarian cancers with faults in the BRCA1 and BRCA2 genes, which are also important for repairing damaged DNA.

Cancer Research UK-funded scientist and study author Professor Nazneen Rahman, head of the Division of Genetics and Epidemiology at The Institute of Cancer Research and The Royal Marsden, said:

"Women with a fault in RAD51D gene have a one in 11 chance of developing ovarian cancer. At this level of risk, women may wish to consider having their ovaries removed after having children, to prevent ovarian cancer occurring."

"There is also real hope on the horizon that drugs specifically targeted to the gene will be available."

Ovarian cancer often develops without any clear symptoms and many women only discover they have it once it has spread.**

Professor Nic Jones, Cancer Research UK's chief scientist, said: "It's incredibly exciting to discover this high risk gene for ovarian cancer.

"It's further evidence that a range of different high risk genes are causing the development of breast and ovarian cancer and we hope there are more waiting to be discovered in different cancers.

"We believe the results of this research will help inform personalised treatment approaches and give doctors better information about risks of cancer to tell patients."

Harpal Kumar, Cancer Research UK's chief executive, said: "Survival from ovarian cancer has almost doubled in the last 30 years. This landmark discovery is another piece of the jigsaw deepening our understanding of the disease. We hope this will have a significant impact in providing more personalised treatments for patients based on their genetic make-up, saving more lives from ovarian cancer.

"All of our research is generously funded by the public. This support has allowed us to invest heavily in the identification of DNA changes which paint a picture of which parts of a person's gene set are linked to cancer. This life-changing discovery exemplifies the importance of this research and the importance of ongoing public support."

Cancer Research UK is the largest single funder of ovarian cancer research in the UK – last year it spent more than £12 million of public donations on tackling the disease.

Source: CRUK