Better Genetic Testing Guidelines Needed to Identify More At-Risk Patients

September 25, 2019

Study finds that current guidelines exclude too many and test too narrowly.

A substantial proportion of patients with pathogenic variants in clinically actionable hereditary cancer genes are being missed with current genetic testing guidelines, according to a recent study.

In the largest cohort study of its kind, Ambry Genetics presents detailed evidence on how to improve the guidelines to identify more at-risk patients. In the study, published in Genetics in Medicine, researchers from Ambry and Mayo Clinic applied genetic testing criteria from the National Comprehensive Cancer Network Clinical Practice Guidelines in Oncology to 165,000 patients who underwent multigene,  hereditary cancer panel testing.

Clinicians use guidelines to inform decisions about which patients should receive genetic testing for hereditary cancer and for those patients whose genes should be tested. These guidelines also have implications for how insurance plans cover genetic testing, and for appropriate medical management of patients after testing is complete.

“Over the past several years, multigene hereditary cancer panels have become the standard clinical genetic testing approach. However, genetic testing guidelines and health insurance policies have not evolved at the same pace,” says Holly LaDuca, lead study author and senior manager of Clinical Affairs Research at Ambry Genetics.

Ambry specifically looked at the testing guidelines for BRCA-related Breast and/or Ovarian Cancer Syndrome (HBOC) and for Lynch Syndrome to better understand how the guidelines for these two common, inherited conditions might be improved to identify more at-risk patients.

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The study found that updating BRCA1 and BRCA2 and Lynch syndrome testing criteria to include more medically actionable, cancer-predisposition genes––and relaxing current criteria, such as age-at-diagnosis constraints––would identify more patients at risk for developing hereditary cancer.

The study also found that:

  • 1 in 4 (409/1,518) patients with pathogenic variants in Lynch syndrome genes would have been missed using current Lynch syndrome testing criteria;

  • 1 in 17 (302/5,200) patients with pathogenic variants in BRCA1 and BRCA2 would have been missed using current BRCA1 and BRCA2 testing criteria; and

  • 3 in 5 (7,647/12,847) patients with pathogenic variants in clinically actionable breast and/or ovarian cancer genes would have been missed if tested for BRCA1 and BRCA2 only.

“This study identifies specific opportunities to expand the current testing guidelines to identify more individuals facing increased cancer risks, who would benefit from more intensive cancer surveillance and/or preventive surgeries,” LaDuca says.

In addition, this study showed several new gene-cancer associations that have the potential to impact patient care. For example, pathogenic variants in BARD1 were associated with a 2-fold increased risk for breast cancer. However, there are no recommendations for increased breast cancer surveillance for these variants like there are for other genes associated with similar risk.

“Results from this study refined several gene-cancer associations for which there are no recommendations for increased surveillance and/or preventive surgeries,” LaDuca says. “More studies are needed from the genetics community to better understand how these new gene-cancer associations have the potential to impact patient care.”