Use of Polygenic Risk Scores for Prostate Cancer Screening
Peter R. Carroll, MD, MPH, Professor of Prostate Cancer and Urology at the University of California, San Francisco, introduces his talk on polygenic risk scores by asserting that serum prostate-specific antigen (PSA) testing has limitations as a stand-alone screening tool. He explains that hereditary factors have a strong influence on prostate cancer risk and outcomes and that prostate cancer has high heritability. Dr. Carroll argues that while high-penetrance genes are important, they only explain a fraction of prostate cancer risk. Further, numerous genome-wide association studies (GWAS) have identified over 250 single nucleotide polymorphisms (SNPs) associated with risk. Dr. Carroll lays out the potential relevance of polygenic risk scores, showing where the scores have the potential to impact clinical care by supporting risk prediction, diagnosis, treatment decision-making, and prognosis of disease course and outcome. He then reviews a trans-ancestry genome-wide association meta-analysis of prostate cancer that demonstrates that genomic risk score (GRS) was predictive across populations. The study concluded that 269 risk variants were estimated to capture 33.6 percent of familial relative risk (FRR) in men of East Asian ancestry, 38.5 percent in Hispanic men, 42.6 percent in men of European ancestry, and 43.2 percent in men of African ancestry, with higher GRS associated with younger age at diagnosis and family history, but not disease aggressiveness. Dr. Carroll concludes with a summary of the use of GRS in prostate cancer early detection: prostate cancer is related to many risk variants across populations; GRS improves on the use of age and family history in assessing risk, though early detection guidelines have not incorporated GRS use yet; and larger populations (particularly those of African ancestry) require further examination.
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