Gen-Probe's (Nasdaq: GPRO) PROGENSA® PCA3 assay can help predict the outcome of initial prostate biopsies in men suspected of having prostate cancer, according to a study of the molecular urine test presented in a scientific poster last week at the 25th annual European Association of Urology (EAU) Congress in Barcelona, Spain.
PCA3 is a gene that is highly over-expressed in more than 90% of prostate cancers.
"Previous studies have demonstrated the clinical utility of PCA3 testing in guiding repeat biopsy decisions," said Professor Alexandre de la Taille of Hopital Henri Mondor in Paris, France. "This study is the first to show that the PROGENSA PCA3 assay also can help determine whether a man suspected of having prostate cancer should undergo an initial biopsy. In addition, the study showed that PCA3 scores may indicate prostate cancer aggressiveness in this group of men."
In the multi-centre study, PCA3 testing was performed on urine samples from 516 men with prostate specific antigen (PSA) levels between 2.5 and 10 ng/mL who were scheduled for an initial prostate biopsy. Approximately 40% of these biopsies were positive. Key study results included:
- The diagnostic accuracy of the PROGENSA PCA3 test, as measured by a statistical technique known as AUC ROC, was maximized by using a PCA3 score of 35 as the cut-off between normal and elevated levels. At this cut-off, the assay had a sensitivity of 64%, a specificity of 76%, and an AUC ROC of 0.761.
- The diagnostic accuracy of the PCA3 test was statistically superior to that of serum total PSA (P<0.0001), PSA density>
- Men with PCA3 scores above 35 were 2.7 times more likely to have a positive biopsy than men with PCA3 scores below 35 (P<0.0001).
- The higher the PCA3 score, the greater the probability of a positive biopsy. For example, cancer was diagnosed in only 20% of men with very low PCA3 scores>
- PCA3 scores correlated with measures of prostate cancer aggressiveness. Specifically, mean PCA3 scores were statistically higher in men with Gleason scores greater or less than 7 (P<0.0001), in men with >33% positive biopsy cores (P<0.0001), and in men with "significant" versus "indolent" cancers, as measured by Epstein criteria>