Genetics

Genetics

Genetics

SGO Genetics Toolkit

genetics-toolkit-graphicsartboard-10The Society of Gynecologic Oncology’s Genetics Toolkit provides critical, practical information to heath care provers interested in gaining a deeper understanding of the role of genetics in gynecologic cancers. While not written for a lay audience, patients and families will gain an appreciation for the complexity of genetic testing and the challenges providers face every day. The toolkit is comprised of specific case studies telling an individual woman’s story.

Frequently Asked Questions

What are genes?
What is genetic testing?
The role of genetic testing in gynecologic oncology
Specific syndromes in gynecologic oncology
How does a patient get genetic counseling and/ or testing?
Additional resources

What are genes?

Genes are the building blocks of all cells that carry the instructions for the body’s functions. Inherited abnormalities in genes are called mutations and are present from birth in the genes of every cell in the body. They can be passed down from either parent and may, in turn, be passed on to children.

What is genetic testing?

Genetic testing involves examining the DNA within genes for mutations in order to determine if someone is prone to develop a disease.

The role of genetic testing in gynecologic oncology

Genetic testing is important to the field of gynecologic oncology because hereditary causes for cancer of the ovaries, fallopian tubes, peritoneum and uterus have been identified. The Society of Gynecologic Oncology supports genetic counseling and testing in selected women, because it may lead to improved cancer prevention and early detection. Genetic results may also help doctors choose the best therapies for some women already diagnosed with gynecologic cancer.

Specific syndromes in gynecologic oncology

Hereditary breast and ovarian cancer (HBOC)
Women diagnosed with epithelial ovarian, tubal, and peritoneal cancers should receive genetic counseling and be offered genetic testing, even in the absence of a family history of cancer. Inherited mutations in genes involved in DNA repair have been shown to cause ovarian, tubal and peritoneal cancer. BRCA1 and BRCA2 mutations account for approximately 15% of ovarian cancer. These mutations lead to a 15 to 50% lifetime risk of developing ovarian, fallopian tube, or peritoneal cancer. Other genes associated with increased risk for ovarian cancer include MSH2, MLH1, MSH6, PMS2, EPCAM, BRIP1, RAD51D, RAD51C, PALB2, BARD1, and TP53. Current estimates are that 25% of women with ovarian, fallopian tube, or peritoneal cancer may carry an inherited mutation in one of these genes.

Lynch syndrome
All women who are diagnosed with endometrial cancer should undergo some type of systematic assessment for Lynch syndrome, which would include a detailed family history of cancer and possible specific tests on the cancer tissue. In addition, women with a family history of endometrial and colon cancer should pursue genetic counseling, regardless of whether they have been diagnosed with cancer. Approximately 3 to 5% of endometrial cancers are due to Lynch syndrome, which is caused by inherited mutations in one of five genes: MLH1, MSH2, MSH6, PMS2, or EPCAM. Patients with Lynch syndrome have a 40 to 60% lifetime risk for endometrial and colon cancer, as well as an increased risk for ovarian cancer. Relying on the family history of cancer alone does not identify all women with Lynch syndrome. In order to better identify Lynch syndrome, broad screening or assessment of endometrial and colon tumors for Lynch syndrome is recommended.

How does a patient get genetic counseling and/ or testing?

A patient interested in undergoing genetic counseling and/or testing should speak to her health care provider to identify an appropriately trained individual who can provide these services.

Many health care providers can order genetic testing. However, not all providers have the experience needed to provide adequate counseling about whom should be tested and which tests to order. Genetic counseling and testing can be conducted by genetic counselors, as well as other knowledgeable medical professionals. Careful pre- and post-test counseling is essential to understanding genetic testing options and results. The increased complexity of testing options and genetic results make detailed, individualized patient counseling by a knowledgeable provider an essential part of the testing process.

In the past, most genetic testing has been done by testing one gene at a time. Next generation sequencing is a new tool that allows inexpensive, rapid DNA sequencing. Cancer gene panels use next generation sequencing technology to assess inherited mutations in multiple genes simultaneously. These first reached the clinical marketplace in late 2011. The unanimous decision by the U.S. Supreme Court in June 2013 invalidated human gene patents, leading to a rapid expansion of clinical options for genetic testing. Current cancer gene panels vary in size from just 2 genes (i.e., BRCA1 and BRCA2) to larger panels that include more than 50 genes.

Advantages of cancer gene panels include decreased cost and improved efficiency of cancer genetic testing by reducing the time involved, number of patient visits, and number of tests sent. The major drawback of cancer gene panels is the increased complexity of the results. While we have clear guidelines for managing cancer risk in the setting of BRCA1 and BRCA2 mutations and Lynch syndrome, for many other genes recommendations for mutation carriers are not established. Involvement of a cancer genetics professional is important to help order the most appropriate genetic test and to interpret the results.

Additional resources