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Clinicians Struggle to Interpret Genetic Test Results, Even After Education, Study Finds

SALT LAKE CITY – Even after taking educational courses, clinicians struggle with interpreting genetic testing results, according to a new study presented this week at the National Society of Genetic Counselors' annual meeting here.

Emily Edelman, associate director of clinical and continuing education at the Jackson Laboratory, and her colleagues have been developing educational programs, including those aimed at clinicians who want to bring genetics into their practices. But, as she noted during her talk, clinicians and other course takers find interpreting certain types of genetic testing results to be challenging.

In a new analysis, they examined how well clinicians fared on quizzes assessing their grasp of certain key cancer genetic testing concepts after they completed one of the Jackson Lab courses. Most of the nearly 800 individuals who took a post-course quiz understood how to deal with positive genetic testing results, but they had difficulties interpreting negative results and variants of uncertain significance.

"Interpreting genetic test results is a complex skill," Edelman said. "It requires an understanding of basic genetics principles, as well as keeping up to date and having an awareness and general understanding of what the strengths and limitations of commonly used genetic test technologies are."

She and her colleagues offer a range of courses, which she noted are reviewed by subject matter experts, pilot tested, and updated every two years to ensure they are in line with current recommendations. For this analysis, they focused on the six programs that teach and assess the interpretation of genetic testing results in the context of hereditary cancers.

Most participants could identify family members who should be offered cascade screening, choose the right genetic test for someone with a known pathogenic variant in their family, and determine how an asymptomatic person who tested positive should be managed clinically.

"People did pretty well here," she said.

The target demographic of these courses was primary care providers, Edelman said, but she noted that their study population included people from a number of specialties like oncology, genetics, primary care, and surgery. The cohort further included not only physicians but also physician assistants, nurses, and a small number of genetic counselors. When Edelman broke down the post-education quiz results for handling positive test results by profession or specialty — though she excluded the genetics professionals — she saw no differences in their performance.

But the course takers struggled with interpreting negative results or variants of uncertain significance. About 13 percent were falsely reassured with uninformative negative results, such as when a patient with a clinical diagnosis for a hereditary cancer syndrome received a negative result. This, Edelman said, could mean that they might consider that patient to have a population-level risk and not offer additional screening based on their family history.

Additionally, nearly 60 percent could not interpret a true negative result. This, she said, is a scenario in which a known pathogenic variant has been found in an unaffected patient's family member and the patient tests negative for it. About 40 percent of the course takers said that that person would still be at increased risk of developing cancer and 20 percent said that person's risk was unknown.

Interpreting variants of uncertain significance also posed problems for participants, as about 40 percent said they'd suggest testing of their unaffected patient if a sibling was found to have a VUS in BRCA1, which is not recommended.

This time, when Edelman broke down the post-education quiz results by profession or specialty, there were differences. Nurses, she reported, had lower knowledge than physicians, physician assistants, or nurse practitioners. Additionally, primary care providers and obstetricians-gynecologists had lower knowledge than other specialties on the VUS questions.

Edelman noted that most genetic counselors consider interpreting a true negative result to be straightforward, but her analysis indicates it is an area of difficulty for clinicians. While this has led her team to question how well their education programs are faring, these efforts shouldn't assume clinicians grasp these concepts in the same way as genetic counselors, she said.

"It makes sense," she said. "When you see a strong family history, you may be uncomfortable letting that go just in the face of a negative genetic test result. But I think that's the place where education and reinforcement from genetics colleagues really can help."

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