PCA3: A Urine-Based Genetic Assay for Detection of Prostate Cancer in Men with Elevated PSA
ED Crawford, J Qian, K Drewnowska, S Varvel, M Wilk, L Mason, A Barqawi, J Kaminetsky, T Huisman, M Bilowus, S Freedman, DG Bostwick. University of Colorado, Aurora, CO; Bostwick Laboratories, Glen Allen, VA; University Urology Associates, New York, NY; Chiramonte Huisman Zorn Urology, Clinton, MD; Bilowus Medical, Reston, VA; Sheldon J Freedman, M.D., LTD, Las Vegas, NV
Background: Serum PSA has been labeled the most important tumor marker in oncology and is a valuable screening tool for prostate cancer. However, since it is not prostate-cancer specific, there is no threshold that separates men with and without cancer with a high level of accuracy. We investigated the value of PCA3 in predicting the likelihood of prostate cancer.
Design: We undertook a prospective, multi-practice, community-urologist-based, and IRB approved clinical trial to evaluate PCA3. Urine samples were obtained from 974 men with elevated serum PSA (> 2.5ng/ml) and/or abnormal digital rectal examination prior to routine 10-core prostate biopsy following standard study protocol in 30 medical practices. Urine samples were processed within 48 hours of collection. PCA3 and PSA mRNA were isolated, amplified and quantified by magnetic target capture, transcription-mediated amplification, and chemiluminescent hybridization protection assay technologies. The PCA3 value was determined using the ratio of PCA3 mRNA copy number to the PSA mRNA copy number multiplied by 1,000.
Results: In total, 380 of 974 patients (39%) were diagnosed with prostate cancer, with a mean Gleason score of 7 (range, 6-9) and 26% (range 1-100%) of specimen involvement by cancer. An additional 106 cases (11%) had only high-grade PIN and/or atypical small acinar proliferation suspicious for cancer (ASAP), and 488 cases (50%) were benign. The mean PCA3 value in men with prostate cancer was significantly higher than in those without cancer (48 vs. 26, p < 0.0001). PCA3 score was associated with the presence of cancer (p < 0.0001) and Gleason score (p=0.0001), but was not associated cancer volume (p=0.56). Using a cutoff value of 35, PCA3 had an odds ratio of 2.6 for predicting prostate cancer. PCA3 had a specificity of 77% and a sensitivity of 44% for the diagnosis of prostate cancer, while the specificity and sensitivity for serum PSA were 22% and 87%, respectively.
Conclusions: We found that the PCA3 urine test significantly improved the specificity for the detection of prostate cancer compared to serum PSA.
Category: Genitourinary (including renal tumors)
Wednesday, March 11, 2009 9:30 AM
Poster Session V # 92, Wednesday Morning