New Multigene Test Improves Assessment of Hereditary Cancers

New clinical data shows that a test covering multiple relevant genes not only detects more deleterious mutations than single cancer tests, but also helps solve the overlap-dilemma that exists among hereditary cancer syndromes.

Myriad Genetics, Inc. (Salt Lake City, UT, USA) has presented clinical studies on the "Myriad myRisk Hereditary Cancer" test at the 50th annual meeting of the American Society of Clinical Oncology (ASCO; Chicago, IL, USA), May 30–June 3, 2014. The test uses next-generation sequencing (NGS) to evaluate 25 clinically significant hereditary cancer genes associated with 8 major hereditary cancers including: breast, colon, ovarian, endometrial, pancreatic, prostate, gastric cancers, and melanoma. The myRisk test results are combined with a patient's personal and family history of cancer and medical society guidelines into a single comprehensive report, making it easier for physicians to tailor treatment plans for patients depending on their level of risk.

"There is robust evidence that hereditary cancers are caused by mutations in many genes and testing for only one hereditary cancer syndrome may lead to missed mutations," said Richard J. Wenstrup, MD, chief medical officer of Myriad, "The Myriad myRisk test solves this dilemma."

The following key studies were featured at ASCO: "Multigene panel testing in patients suspected to have Lynch syndrome," podium presentation by Matthew Yurgelun. This study, using myRisk to test 1,260 patients with a history of hereditary colon cancer, found that 27% of mutation carriers identified by myRisk had mutations in genes not normally associated with hereditary colon cancer. Also important is that more than 1/3 of the additional mutations found were in the BRCA1 and BRCA2 genes, which further demonstrates the overlap that exists between the hereditary breast and colon cancer syndromes.

"A study of ovarian cancer patients tested with a 25-gene panel of hereditary cancer genes," podium presentation by Lucy Langer. This study of 648 patients showed that 15.4% of patients with ovarian cancer had a mutation that was detected by the myRisk panel. Of these patients, 59.6% had mutations in BRCA1 and BRCA2, 34.6% had mutations in the other myRisk panel genes, including hereditary colon cancer genes. myRisk increased the number of positive test results in ovarian cancer patients by 63% over BRCA1 and BRCA2 testing alone.

"Analysis of patients with two hereditary cancers (breast/ovarian or colon/endometrial) who met NCCN genetic testing criteria after their first cancer," poster presentation by Jennifer Saam. In this study, patients with a history of 2 associated cancers were evaluated to determine what percentage of patients met National Comprehensive Cancer Network (NCCN) criteria for genetic testing after their first cancer diagnosis, but who did not receive a test result until after their second cancer diagnosis. The majority of patients had at least 5 years between their first and second cancers. For 9,982 patients with breast and ovarian cancer who were evaluated, the overall rate of BRCA1 and BRCA2 mutations was 22%. Of these, only 56% of patients diagnosed with breast and ovarian cancer met the NCCN criteria for genetic testing after their first cancer. Among 941 patients with colon and endometrial cancer who were evaluated, 28% had mutations in the genes associated with hereditary colon cancer. Of these, 65% of patients met NCCN criteria for genetic testing after their first cancer. These findings underscore the importance of diagnosing patients with hereditary cancer syndromes after their first cancer so that a second cancer can be prevented or identified early.

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