AUA: Molecular Markers May Identify Prostate Cancer
Tests for PCA3, free circulating DNA may represent improvement over standard PSA test
TUESDAY, June 1 (HealthDay News) -- In men with elevated serum prostate-specific antigen (PSA) and/or an abnormal digital rectal examination, two new tests -- a urine test that measures prostate cancer gene 3 (PCA3), and a blood test that measures free circulating DNA -- may more accurately predict prostate cancer than the standard PSA test, according to research presented at the annual meeting of the American Urological Association, held from May 29 to June 3 in San Francisco.
In one study, E. David Crawford, M.D., of the University of Colorado in Denver, and colleagues analyzed the PCA3 level in urine samples from 1,946 patients. In men with prostate cancer, they found that the mean PCA3 value was significantly higher than in those without cancer (50 versus 25). Compared to the PSA test, they found that the PCA3 test (using a cutoff value of 35) was more likely to predict prostate cancer (odds ratio, 3.4 versus 1.7), and had a specificity of 78 percent and a sensitivity of 49 percent compared to a specificity and sensitivity for serum PSA of 21 and 87 percent, respectively.
In a related study, Rakesh Singal, M.D., of the University of Miami Miller School of Medicine, and colleagues measured free circulating DNA in blood samples from 252 patients. Compared to levels at or below 180 ng/mL, their adjusted analysis showed that levels above 180 ng/mL were significantly associated with prostate cancer risk (odds ratio, 2.15), and that further adjustment for PSA did not change the estimated effect or significance of free circulating DNA (odds ratio, 2.34).
"Our study suggests that free circulating DNA levels may improve the sensitivity and specificity of PSA screening for prostate cancer detection," Singal and colleagues conclude.