Ovarian Cancer Gene Discovery May Improve Treatment Possibilities
The risk of a woman developing ovarian cancer increases from 1 in 70 to 1 in 11 if she has a mutated DNA repair gene called RAD51D. The newly discovered faulty gene may actually help researchers improve treatment possibilities as well as their understanding of cancer risks.
Ovarian cancer is a challenge to diagnose and treat
It is estimated that nearly 22,000 women in the United States will be diagnosed with ovarian cancer in 2011, and that about 15,000 women will die of the disease. Ovarian cancer often causes no symptoms in the early stages, and many cases are not diagnosed until the cancer is more advanced, which makes treatment much more challenging and less likely to succeed.
In the new study, which was led by Professor Nazneen Rahman at The Institute of Cancer Research, the research team made their discovery while they were examining DNA from women in 911 families with ovarian and breast cancer and comparing it to the DNA from 1,060 controls in the general population.
The team found eight of the faulty RAD51D genes in unrelated women with cancer, but only one such gene among the controls. Three mutations were found in 59 of the families who had three or more members with ovarian cancer.
A properly functioning RAD51D gene repairs damaged DNA. When the gene is faulty, however, this critical repair function is affected, and damaged DNA accumulates in cells and increases the risk of developing into cancer.
The team also discovered that cells deficient in RAD51D were sensitive to PARP (Poly ADP ribose polymerase) inhibitors, a new class of cancer drugs designed to inhibit the activity of the enzyme, which is involved in the repair of DNA as well as programmed cell death. Previous research has indicated PARP inhibitors may be helpful in treating ovarian and breast cancers associated with other mutated genes (BRCA1, BRCA2), which are also involved in DNA repair.
Given that women who have a faulty RAD51D gene have a 1 in 11 chance of developing ovarian cancer, Rahman noted that these women “may wish to consider having their ovaries removed after having children, to prevent ovarian cancer occurring.” The presence of a mutated RAD51D gene may join the list of other risk factors for the disease, which currently includes a family history of ovarian cancer, a personal history of breast, uterine, colon, or rectal cancer, age 55 and older, never pregnant, and possibly the use of estrogen therapy for 10 or more years.
It was “incredibly exciting to discover this high risk gene for ovarian cancer,” according to Professor Nic Jones, chief scientist at Cancer Research UK, which funded the study. Jones noted that “the results of this research will help inform personalized treatment approaches and give doctors better information about risks of cancer to tell patients.”