To evaluate, in a multicenter study, the diagnostic performance of a new molecular test uPM3 for detecting prostate cancer cells in urine because of the need for better methods to identify patients at risk of prostate cancer.

The uPM3 test is a nucleic acid amplification assay detecting simultaneously in the urine the relative expression of prostate-specific antigen (PSA) mRNA as a marker of prostate cells and PCA3RNA, which is selectively expressed in most types of prostate cancer. The test is performed using the isothermic nucleic acid-based amplification method, and the two targets are simultaneously detected in real-time fluorescence using specific beacons as probes in a thermostated spectrofluorometer. The test was performed on the first voided urine obtained after careful digital rectal examination of the prostate in men undergoing transrectal ultrasound-guided prostate biopsy.

Of 517 patients undergoing biopsy at five centers, 443 (86%) had an assessable sample. Of those, 21%, 55%, and 24% had a total PSA level of less than 4 ng/mL, between 4 and 10 ng/mL, and greater than 10 ng/mL. The corresponding percentage of biopsies positive for cancer in these three groups was 20%, 35%, and 44%. The overall uPM3 sensitivity and specificity was 66% and 89%, respectively. In men with a PSA level less than 4 ng/mL, the sensitivity was 74% and specificity 91%. In those with a PSA level of 4 to 10 ng/mL, the sensitivity was 58% and specificity 91%. In those with a PSA level greater than 10 ng/mL, the sensitivity and specificity was 79% and 80%, respectively. The positive predictive value of uPM3 was 75% compared with 38% for total PSA, and the negative predictive value was 84% compared with 89% and 80% for a PSA cutoff of 2.5 and 4.0 ng/mL, respectively. The overall accuracy was 81% compared with 43% and 47% for total PSA at a cutoff of 2.5 and 4.0 ng/mL, respectively.

These results suggest that the uPM3 molecular urine test may be an important adjunct to current methods for the detection of early prostate cancer.