UPM3: review of a new molecular diagnostic urine test for prostate cancer

PSA elevation is the most common indication for urologic referral to rule out the presence of prostate cancer. Recently PSA screening and its usefulness in suggesting the presence of clinically significant prostate cancer has been put into doubt. PSA has limitations in detecting significant cancers even when elevated and on the other hand significant cancers are found in the presence of low PSA levels. In order to better predict patients at risk of harboring prostate cancer new diagnostic tests are required. A promising novel approach is based on the molecular detection of prostate cancer cells in urine. The uPM3 assay is based on the amplification of specific target RNA using the nucleic acid sequence-based amplification (NASBA) technology. In a large multi-center study of 517 cases the overall sensitivity was 66% with a specificity of 89%. The positive (PPV) predictive values for the uPM3 test were 75% compared to 38% for a serum PSA cutoff of 4. The negative predictive value (NPV) was equivalent between the tests, but due to the higher PPV for uPM3, the accuracy of uPM3 was nearly two-fold greater than PSA (81% versus 43% and 47% for PSA cutoffs of 2.5 and 4 ng/ml, respectively). This test may become one of the first molecular diagnostic tools to aid in prostate cancer detection.