On July 7, 2020 Myriad Genetics, Inc. (NASDAQ: MYGN), a leader in molecular diagnostics and precision medicine, reported two recent publications validating the polygenic risk score (PRS) component of Myriad’s breast cancer risk stratification tool riskScore (Press release, Myriad Genetics, JUL 7, 2020, View Source [SID1234561739]). The publications clinically validate both the ability of the PRS component of riskScore to predict breast cancer risk in asymptomatic women and modify risk estimations for patients identified with pathogenic mutations.

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"Historically we’ve considered breast cancer risk most significant for women diagnosed with pathogenic mutations in hereditary cancer genes. These studies demonstrate clearly that other genetic factors evaluated through Myriad’s riskScore test can dramatically alter breast cancer risk both independent of, and in combination with, gene mutations," said Nicole Lambert, president of Myriad International, Oncology and Women’s Health. "This information can dramatically change patient clinical management and Myriad is currently working diligently to provide access to this important information for all women."

The first study published in JCO Precision Oncology described the PRS component of riskScore in over 150,000 women. It showed that independent of other hereditary breast cancer gene mutations (e.g., BRCA1), Myriad’s polygenic risk score can add great value and precision to breast cancer risk estimates. The PRS was highly associated with breast cancer risk with an odds ratio of 1.47 (95% confidence interval 1.45 to 1.49) per unit standard deviation in the PRS. This translated to women in the top PRS percentile having a three-fold higher risk of breast cancer than an average risk patient.

The second study published in the Journal of the American Medical Association Network Open demonstrates the ability of Myriad’s polygenic risk score to improve breast cancer risk stratification in women diagnosed with pathogenic mutations in common breast cancer genes. The study evaluated over 150,000 patients and approximately 10,000 patients who were carriers of pathogenic mutations in the BRCA1, BRCA2, CHEK2, ATM and PALB2 genes who were tested at Myriad. The study demonstrated that patients with high penetrant genes such as BRCA1 and BRCA2 did not warrant changes in clinical management; however, breast cancer risks in patients with moderate penetrant genes such as CHEK2, ATM, and PALB2 could vary significantly, warranting different clinical management considerations. For example, patients with a PALB2 mutation historically have been assessed to have an approximately 50 percent lifetime risk for breast cancer. However, after incorporating the data from Myriad’s 86 single nucleotide polymporphism (SNP) riskScore test, patient risks varied between 26 percent to 79 percent (see Graph 1 below).

"These are some of the largest polygenic risk score studies ever published. Patient medical management can vary dramatically depending on where patients with and without pathogenic mutations fall within the risk spectrum," said Thomas P. Slavin M.D., senior vice president for Medical Affairs in Oncology at Myriad Genetic Laboratories. "This information will help empower patients and clinicians to make more informed decisions based upon the most precise breast cancer risk estimates availiable."

About riskScore
riskScore is a new clinically validated personalized medicine tool that enhances Myriad’s myRisk Hereditary Cancer test. riskScore helps to further predict a women’s lifetime risk of developing breast cancer using clinical risk factors and genetic-markers throughout the genome. The test incorporates data from more than 80 single nucleotide polymorphisms identified through 20 years of genome wide association studies in breast cancer and was prospectively validated in our laboratory to predict breast cancer risk in women of European descent. This data is then combined with a best-in-class family and personal history algorithm, the Tyrer-Cuzick model, to provide every patient with individualized breast cancer risk.