Ovarian Cancer and Genetic Risk

Ovarian Cancer and Genetic Risk

Women with a family history of ovarian cancer and those newly diagnosed with the disease often have questions about the role of hereditary risk. The reality is that most (90 percent) cases of ovarian cancer are sporadic, or not the result of an inherited genetic mutation; 10 percent are linked to hereditary syndromes. Here, Megan Myers, MS, genetic counselor at UCSF Medical Center at the University of California, San Francisco answers some common questions about hereditary risk and genetic testing.

Which hereditary cancer syndromes are associated with ovarian cancer?

While research has established two main hereditary cancer syndromes— hereditary breast and ovarian cancer syndrome and Lynch syndrome— knowledge of other, less common causes of hereditary ovarian cancer is continuing to expand the landscape of research in this field. Myers says that research related to the role of inherited risk in ovarian cancer is evolving quickly. “If you had asked me to discuss genetic mutations linked to ovarian cancer five years ago, I would have given you a straightforward answer,” Myers says, “but we are continuing to learn so much that the answer is changing rapidly. Genetic testing has been advancing quickly, and we are continuing to discover new genes that are linked to an inherited risk for ovarian cancer.”

Who should undergo genetic testing?

According to Myers, women with any of the following risk factors should consider seeking genetic counseling to see if they are a candidate for testing:

  • Women with a family history of breast or ovarian cancer
  • Women diagnosed with an epithelial ovarian cancer at any age
  • Women with a family history of breast, ovarian, colon, or endometrial cancer
  • Women diagnosed with cancer at an early age (such as premenopausal breast cancer)
  • Women with multiple cancer diagnoses
  • Women with Ashkenazi Jewish ancestry

When should women undergo genetic testing?

Ideally, Myers says, a woman should undergo genetic testing before she is diagnosed with cancer, though this special report: ovarian cancer is obviously not always possible. “The next best scenario is if genetic counseling and testing can occur before a patient undergoes surgery or other treatment,” she says. This is because if there is a chance to avoid additional surgery that might be recommended based on genetictesting results, surgical procedures could be combined to avoid risks associated with multiple surgeries. Results can also in some cases qualify an individual for a clinical trial, Myers says, adding to the incentive to test before treatment begins.

Why is genetic counseling important?

A genetic counselor plays a key role in helping patients and families understand the information that testing provides. For those who receive a positive result that shows they have inherited a specific hereditary syndrome, Myers says that counselors can provide individualized risk assessment plans for patients and their family members and coach them through screening protocols associated with their results and through sharing information with extended family. For those whose genetic-testing results are negative, meaning no genetic mutation has been identified, Myers says, a counselor will still carefully consider family history and may recommend earlier or more-frequent screening.

Hereditary Syndromes Related to Ovarian Cancer

Though new information about genes related to ovarian cancer risk is emerging, at this point there are two established hereditary syndromes linked with an increased risk of ovarian cancer, which Megan Myers defines here.

  • Hereditary breast and ovarian cancer syndrome is caused by mutations in the BRCA1 and BRCA2 genes. These genes act as tumor suppressor genes to protect women and men from certain cancers, such as breast, ovarian, melanoma, prostate, and pancreatic cancer. Women who have a BRCA1 or BRCA2 gene mutation have a 30 to 50 percent chance of developing ovarian cancer in their lifetime.
  • Lynch syndrome is caused by an inherited genetic mutation in an individual’s mismatch repair genes, called MLH1, MSH2, MSH6, and PMS2. These genes are involved in fixing mistakes that occur during DNA replication. A person who has Lynch syndrome is at an increased risk of developing colon, endometrial (uterine), ovarian, stomach, small bowel, pancreatic, urinary tract, brain, and skin cancers. A woman who has Lynch syndrome has up to a 15 percent lifetime chance of developing ovarian cancer.

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