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Peter Beitsch MD and Pat Whitworth MD/

Obsolete Guidelines for Genetic Testing Miss Breast Cancer Patients Who Could Benefit

Underdiagnosis of Hereditary Breast Cancer: Are Genetic Testing Guidelines a Tool or an Obstacle?

Approximately 330,000 patients are diagnosed with breast cancer every year in the United States, with an estimated 10% of them likely due to hereditary causes. However, data from the TME Breast Care Network presented at the recent San Antonio Breast Cancer Society meeting, and published in the Journal of Clinical Oncology online December 7, shows that the existing guidelines exclude providing genetic testing for many patients with medically relevant genetic changes.

The study of 1000 patients from 20 clinical sites showed no statistically significant difference in the number of mutations identified by genetic testing between those patients who qualified for genetic testing and those who did not.  Current testing guidelines were developed to identify carriers of BRCA1/2 variants, but newer expanded panel testing yields additional pathogenic and likely pathogenic variants. The study was designed to determine if the current National Comprehensive Cancer Network (NCCN) guidelines for genetic testing were still accurate in identifying patients with hereditary breast cancer when using expanded panel testing that included other pathogenic variants, 82% of which have clinical implications for patients and/or unaffected family members.

P-LP Variants and NCCN Criteria

This study performed by the TME BCN network of mostly community-based physicians, may be the only study on this topic published from data collected from practicing physicians from multiple community-based institutions. They compared the results from expanded panel genetic testing between patients who met and did not meet 2017 NCCN guidelines and found no statistically significant difference in the pathogenic variant rate between the two groups.

These results support simplifying the guidelines to one standard: universal genetic testing for breast cancer patients.  Testing all breast cancer patients would identify more patients harboring actionable variants and provide them, their physician, and their families with best treatment options knowing their genetic profile. In addition, identifying variants in breast cancer patients opens the door for cascade testing of family members to allow them true opportunities for prevention or early intervention.

The results from this study indicate that nearly half of breast cancer patients with a pathogenic variant that could be clinically actionable and/or offer management guidelines, are missed by current testing guidelines. The authors of this study strongly endorse a recommendation for all patients with a diagnosis of breast cancer undergo expanded panel genetic testing.

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