Genetic test may improve prostate cancer risk assessment
"The genetic test outperformed the [prostate-specific antigen] PSA test in assessing cancer risk," A. Karim Kader, MD, PhD, urologic surgeon at University of California San Diego Health System, said in a release. "If results of this blood test were factored into prostate cancer predictors such as total free PSA, free PSA, number of core samples taken at biopsy, and family history, we would have a more accurate picture of whether or not a man is likely to develop the sometimes fatal disease."
Kader and colleagues evaluated 1,654 men in the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) clinical trial in the four-year study. The men had biopsies and underwent genetic studies that looked for the presence of 33 single nucleotide polymorphisms (SNPs), genetic variations within an individual's DNA sequence which may have a positive association with prostate cancer risk as well as other chronic diseases.
A total of 410 men had positive biopsy for prostate cancer during the study period. These men differed significantly from men with negative biopsies for most clinical and demographic variables.
Baseline variables, such as genetic score and total PSA levels, had an area under the curve (AUC) ranging from 0.51 to 0.59. AUC was highest for genetic score.
When Kader and colleagues conducted a reclassification of risk based on the addition of genetic markers, they found risk was reclassified in 33 percent of men, which provided a net reclassification benefit of 10 percent.
“Finally, adding the genetic score to existing clinical predictors allows for fewer biopsies to identify the same number of overall and high-grade prostate cancer patients,” wrote Kader et al. This may provide clinical, economic and public health benefits by reducing the morbidity, cost and mortality associated with biopsy.
Although the actual clinical value of the results is unknown as the increase in AUC was slight, the researchers noted the information may help guide men and their physicians as they make decisions about repeat biopsies.
"Avoiding repeat procedures, particularly in older men, can help reduce the risk of infection and potential hospitalizations," said Kader. "The genetic score is available at any time in a man's lifetime and could be used as a pre-screening test thus leaving aggressive PSA screening to men at a higher genetic risk."