PSA Is Not Enough to Assess Prostate Cancer Risk
Canadian researchers say it may be time to move beyond PSA-based predictions of prostate cancer risk. New technology and gene-based markers make it possible to use a more individualized approach that considers all prostate cancer risk factors.
“We showed that age, ethnicity, a family history [of the disease], and urinary symptoms are important predictors for having prostate cancer, and they are just as important as the PSA test,” said Robert Nam, MD, associate professor of surgery at Sunnybrook Health Sciences Centre, part of the University of Toronto.
He and his colleagues have quantified how various combinations of risk factors and the presence of genetic markers affect the likelihood of being diagnosed with prostate cancer. Based on their findings, they developed a nomogram to estimate a man's risk at the time of screening.
The genetic markers include single-nucleotide polymorphisms (SNPs), which flag potential genetic mutations that could modify the risk of having prostate cancer. When Dr. Nam and his coworkers examined whether these and other markers could be used clinically in a nomogram, “we certainly found they were very important in predicting prostate cancer.”
“Genetic factors are very important in predicting risk, and we will be using them in the near future [for that purpose],” Dr. Nam said. “In the next two years, we may see some of this [research] coming to fruition. We have found SNPs that are very important in predicting aggressive prostate cancer.”
Current PSA screening recommendations should not be changed, but PSA values should be considered in the context of other factors, Dr. Nam said.
While many physicians still just look at the PSA value alone, clinicians would be well-advised to use nomograms, he stated, noting that two are widely available on the Internet. That includes the nomogram he developed with colleagues, which is available at www.prostaterisk.ca; the other is available through the National Cancer Institute Web site (www.cancer.gov).