A team of researchers have developed a genetic prognostic tool that may help predict the age of onset of aggressive prostate cancer in men.

The new polygenic hazard score is intended to better inform men whether and when to undergo Prostate-Specific Antigen (PSA) Test, widely used for prostate cancer screening.Since an individual's genotype does not change with age, the polygenic hazard score can be calculated at any time and used as a tool for men deciding whether and when to undergo screening for prostate cancer. The score involves survival analysis to estimate the effect of individual genomes for small variations, called single-nucleotide polymorphisms (SNPs), on age at diagnosis of aggressive prostate cancer. 

This is especially critical for men at risk of developing prostate cancer at a very young age, before standard guidelines recommend consideration of screening."The polygenic hazard score is very versatile and can be applied to many age-related diseases," said Chun Chieh Fan, from the University of California - San Diego."In this case, the polygenic hazard score of prostate cancer captures the age variations of aggressive prostate cancer."The score has already been proven to be very useful in predicting age of onset for Alzheimer's disease, the researchers said.

For the study, described in the journal BMJ, used data from over 200,000 SNPs, from 31,747 men of European ancestry.When men with a high polygenic hazard score were compared to those with average polygenic hazard score, their risk of aggressive prostate cancer was at least 2.9 times greater, the researchers said, adding that this kind of genetic risk stratification is a step toward individualised medicine.Further, PSA tests are much more predictive of aggressive prostate cancer in men with high polygenic hazard score than in those with low polygenic hazard score. This suggests that the score can help physicians determine whether to order a PSA test for a given patient.