NEW YORK (Reuters Health) - Urine testing for the prostate cancer gene 3 (PCA3) is more accurate than serum PSA testing in predicting the result of repeat prostate biopsy, according to a report in the March 27th issue of Urology.

Men with elevated PSA levels, but negative prostate biopsy results present a diagnostic dilemma, lead author Dr. Leonard S. Marks, from the University of California in Los Angeles, and colleagues note. Watchful waiting with serial PSA testing is often employed, but this can create anxiety and may also result in unnecessary medical procedures.

Unlike PSA, which can be elevated with benign as well as malignant prostate disease, PCA3 appears to be specific for prostate cancer. In the present study, Dr. Marks' team assessed the ability of urine PCA3 testing to detect prostate cancer in 233 men with elevated PSA levels and at least one prior negative prostate biopsy. A PCA3 score was determined for each subject using a highly sensitive quantitative assay. This score was then compared with serum PSA testing in predicting the outcome of repeat prostate biopsy.

Overall, 226 of the men had adequate amounts of urinary RNA to facilitate PCA3 analysis, the report indicates. Sixty of the men (27%) had prostate cancer on repeat biopsy.

On receiver operator curve analysis, the area under the curve for the PCA3 score was 0.68, higher than the 0.52 value seen with PSA testing.

With a PCA3 score cutoff of 35, the test was 58% sensitive and 72% specific in detecting prostate cancer. Twelve percent of men with a score less than 5 had prostate cancer on repeat biopsy. With a score greater than 100, the likelihood of a positive biopsy was 50%.

"In men with elevated serum PSA levels and previous negative prostate biopsy findings, the determination of the urinary PCA3 levels appears to have value in the prediction of repeat biopsy outcomes," the researchers conclude.