Genetic markers could improve prostate cancer test
Analysing small genetic variations (called SNPs) could provide a more accurate gauge for men's prostate cancer risk, report scientists at the company deCODE genetics.
But Cancer Research UK scientists said more work would need to be done before this discovery could be used in testing for prostate cancer.
The most common way to screen for prostate cancer is to test levels of prostate specific antigen (PSA). Men whose PSA levels are shown to be over a certain threshold are then recommended for a biopsy. However, raised PSA levels are not always caused by a prostate cancer, which means that some men are biopsied unnecessarily. And sometimes men with prostate cancer do not have high enough PSA levels to be recommended for a biopsy.
Scientists at the company deCODE genetics have suggested that a more personalised PSA threshold can be established by analysing four SNPs in a man's genetic make-up, which could help to ensure that the most high-risk men are recommended for biopsy.
The SNPs all help to determine an individual's baseline levels of PSA. They were identified through the analysis of more than 300,000 SNPs in 16,000 Icelandic men.
In a paper published in the online edition of the journal Science Translational Medicine, the researchers detail how the ratio of positive to negative biopsies could be improved by creating a personalised PSA threshold by analysing these four SNPs.
"Like virtually every protein in the body, PSA levels vary between individuals according to SNPs that regulate gene expression," commented Kari Stefansson, CEO of deCODE and senior author on the study.
But Professor Richard Martin, a Cancer Research UK-funded prostate cancer expert based at the University of Bristol, pointed out that: "Because the study involved so many men, the researchers were able to spot small effects of genes on PSA. Although this is interesting scientifically, it does however mean that the associations between genes and PSA levels are so small that they can't yet be used to distinguish between men who do and don't have prostate cancer.
"The personalised PSA cut off levels from this study made very little difference to the number of false positive and false negative cancers that were detected.
"More research is required before individualised PSA levels, based on a man's genetic makeup, could be used in practice."