A genetic risk score to personalize prostate cancer screening, applied to population data.

Abstract

181 Background: Genetic risk stratification may inform the decision of whether—and at what age—a man should undergo prostate cancer (PCa) screening. We previously validated a polygenic hazard score (PHS) for accurate prediction of age of onset of aggressive PCa and for improved screening PSA performance. The PHS is a weighted sum of 54 SNP genotypes. Here, we applied the PHS to population data to assess its potential impact on individualized screening. Methods: Age-specific PCa incidence data were obtained for men aged 40-70 years from the United Kingdom (Cancer Research UK, 2013-2015) and fit to an exponential curve as a continuous model of age-specific PCa incidence. Using hazard ratios estimated from ProtecT study data, annualized incidence rate curves were calculated for the following percentiles of genetic risk: 1, 5, 20, 50, 80, 95, and 99. The proportion of incidence classified as aggressive (Gleason score ≥7) was estimated as 59.7%, the reported result from the CAP trial. PHS was combined with incidence data to give a risk-equivalent age, when a man with given PHS percentile will have the same risk of aggressive PCa as that of a typical man at age 50 years. Results: The age-specific incidence rate of PCa for the UK population was modeled as: 0.004 e0.203(age-40) ( R2 = 0.957, p = 0.001). Table shows risk-equivalent age for each genetic risk percentile. For example, a man with a PHS in the 95th percentile reached PCa risk equivalent to a typical 50-year-old man at age 44 years; conversely, a man with a PHS in the first percentile does not reach this risk level until age 60 years. Initiation of screening discussions could be adjusted accordingly. Conclusions: PHS may inform PCa screening with individualized estimates of risk-equivalent age for aggressive PCa. Risk-equivalent age for aggressive prostate cancer, by PHS percentile. [Table: see text]