Ovarian Cancer: What Genes Have To Do With It

The "BR" stands for breast, because the genes also increase the risk of breast cancer. Doctors call these genes "high penetrance genes," because if a patient inherits them, she or he has a markedly increased risk for pancreatic, male prostate and breast cancer.

A woman who inherits the BRCA1 gene has a 44% lifetime risk (by age 80)  for developing ovarian or fallopian tube cancer., and 70-80% risk of developing breast cancer.

Compared to BRCA1, the BRCA2 gene carries a lower risk, but women who have it are still more likely to develop cancer than women who don't. For ovarian and fallopian tube cancer, it’s a 17 percent lifetime risk, and about 70 percent for breast cancer.

Ovarian cancer usually develops in women who are post-menopause. But younger women can have the disease as well, especially if they carry the BRCA-1 or BRCA-2 genes.

Women should consult with their doctor to learn about BRCA genes they may carry. There are many commercially-available tests for genetic risk but they are not always comprehensive in their gene coverage. A study found that the DNA 23andME may be highly unreliable for determining cancer risk. The study, which has not been peer reviewed and was conducted by a market rival of 23andME, finds that 23andME can miss the BRCA genes in 90 percent of women.

Dr. Ophira Ginsburg, director of the High-Risk Cancer Program at NYU Perlmutter Cancer Center, said the study results are largely correct in being skeptical of ancestry DNA tests to find cancer-related genes.

"BRCA1 and BRCA2 each of those genes have at least 1,000 different mutations that we know of that can cause an increased risk of cancer," Ginsburg told SurvivorNet. "So this test that's now on the market only tests for three of these. And if you're not from that community of Eastern-European Jews or other communities where these changes have been found, you may mistakenly believe that you're not at risk. The test is negative. So I'm not at risk. And that would give you a false sense of reassurance, particularly if you still have a strong family history of cancer."

Another recent study, at Stanford University, found that women who have ovarian cancer aren’t getting the proper, recommended genetic testing.

"All women with ovarian cancer at time of diagnosis, not at recurrence, but at the time of diagnosis, should undergo genetic testing regardless of family history, the patient's age and histology," says Dr. Ursula Matulonis, Chief of the Division of Gynecologic Medical Oncology at Dana-Farber Cancer Institute.

Current guidelines suggest that all women with the most common type of ovarian cancer undergo genetic testing for cancer-related genes, whether or not they have family history of the disease. But the study, which looked at 83,000 women across California and Georgia, found that under a quarter of women receive the recommended testing.

"I can say that again, it's really important that all women with ovarian cancer be tested at the time of diagnosis regardless of her age, the type of ovarian cancer that she has, as well as her family history," Matulonis says. "We [even] know that women who have no family history of ovarian cancer still can have the BRCA mutation, just because of small families and other reasons."

About 1.3 percent of all women will develop ovarian cancer during their lifetime. For women carrying BRCA1, roughly 44 percent will develop the disease by age 80, as well as about 17 percent of women who inherit a BRCA2 mutation.

Learn more about SurvivorNet's rigorous medical review process.

---