Purpose: We assessed the feasibility of a novel urinary test for prostate cancer based on the presence of alpha methylacyl coenzyme A racemase (AMACR) protein in voided urine specimens obtained after prostate biopsy.
Materials and methods: Clean catch voided urine specimens were prospectively collected from 26 consecutive men immediately after transrectal ultrasound guided prostate biopsy for suspected malignancy. The presence of AMACR was evaluated in a blinded manner by Western blot analysis and correlated with biopsy results and patient clinical information.
Results: AMACR was detected in the urine in 18 of 26 patients (69%). AMACR was detected in all 12 patients with biopsy confirmed adenocarcinoma of the prostate (100% sensitivity, 95% CI 75 to 100), in 5 of 12 with no evidence of cancer on biopsy (58% specificity, 95% CI 29 to 78) and in 1 of 2 (50%, 95% CI 3 to 80) with atypia on biopsy. Overall AMACR detection was associated with cancer status by prostate biopsy in 21 of 26 patients (86%).
Conclusions: We report the feasibility of a novel, noninvasive, nonprostate specific antigen based molecular approach to detect prostate cancer in voided urine. To our knowledge this is the first report of AMACR protein detection in the urine of patients with prostate cancer. A screening test based on urinary AMACR may develop into a useful adjunct to serum prostate specific antigen and digital rectal examination for identifying men at increased risk for harboring prostate cancer despite negative biopsy. Such a test has potential application for stratifying patients into low and high risk groups for surveillance vs repeat biopsy.