Though panel testing to uncover cancer-linked gene mutations in patients is on the rise, Johns Hopkins University's Jennifer Axilbund writes in a Journal of Clinical Oncology editorial that "more testing is not necessarily better testing."
In a paper also appearing in JCO, researchers from the Peter MacCallum Cancer Center and elsewhere report that panel test only occasionally uncovered potentially actionable mutations beyond BRCA1 and BRCA2. Other than those, they note that they only observed an excess of mutations in PALB2 and TP53 in their cohort of 2,000 breast cancer cases and 1,997 cancer-free controls.
Similarly, a second paper from a team at Harvard Medical School and elsewhere reports in JCO that in their panel testing of germline DNA from 488 breast cancer patients, the most common mutations uncovered were also in BRCA1 and BRCA2, followed by CHEK2, ATM, and BRIP1.
As Axilbund notes, both sets of researchers call for increased panel testing to not only identify families with high disease risk, but also to better understand the importance of the less well-characterized risk genes.
However, Axilbund argues that panel testing could cause harm to individual patients. "Highly trained genetics providers are struggling with not only how to classify various molecular findings, but also with how — or even if — to use them to influence medical management of the patient and family," she adds.
Because of that and other factors, including the continual addition of new genes to panel tests, she says, "complex, clinical panel-based genetic testing should be approached with extreme caution."