PCA3 Molecular Urine Assay Correlates With Prostate Cancer Tumor Volume

Implication in Selecting Candidates for Active Surveillance

Nakanishi, Hiroyuki
Groskopf, Jack
Fritsche, Herbert A.
Bhadkamkar, Viju
Blase, Amy
Kumar, S. Vikas
Davis, John W.
Troncoso, Patricia
Rittenhouse, Harry
Babaian, R. Joseph

^aDepartment of Urology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas
^bDepartment of Pathology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas
^cDepartment of Laboratory Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, Texas
^dGen-Probe Incorporated, San Diego, California

Supported by Gen-Probe Incorporated, Atlanta, Georgia.

See Editorial on page 1658.

For another article on a related topic see page 2020.

^§ Correspondence and requests for reprints: Department of Urology, Unit 1373, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, Texas 77030 (telephone: 713-563-7471; FAX: 713-794-4824; e-mail: [email protected]).

^* Financial interest and/or other relationship with Gen-Probe.

^† Financial interest and/or other relationship with Intuitive Surgical.

^‡ Financial interest and/or other relationship with Endocare and Gen-Probe.

Received August 27, 2007

Journal of Urology 179(5):p 1804-1810, May 2008.

Purpose

Prostate cancer gene 3 (PCA3) has shown promise as a molecular marker in prostate cancer detection. We assessed the association of urinary PCA3 score with prostatectomy tumor volume and other clinical and pathological features.

Materials and Methods

Urine specimens were collected after digital rectal examination from 59 men scheduled for prostate biopsy and 83 men scheduled for radical prostatectomy. Prostatectomy findings were evaluable for 96 men. PCA3 and prostate specific antigen mRNAs were quantified with Gen-Probe DTS® 400 System. The PCA3 score was defined as the ratio of PCA3 mRNA/prostate specific antigen mRNA ×10³.

Results

The PCA3 score in men with negative biopsies (30) and positive biopsies (29) were significantly different (median 21.1 and 31.0, respectively, p = 0.029). The PCA3 score was significantly correlated with total tumor volume in prostatectomy specimens (r = 0.269, p = 0.008), and was also associated with prostatectomy Gleason score (6 vs 7 or greater, p = 0.005) but not with other clinical and pathological features. The PCA3 score was significantly different when comparing low volume/low grade cancer (dominant tumor volume less than 0.5 cc, Gleason score 6) and significant cancer (p = 0.007). On multivariate analysis PCA3 was the best predictor of total tumor volume in prostatectomy (p = 0.001). Receiver operating characteristic curve analysis showed that the PCA3 score could discriminate low volume cancer (total tumor volume less than 0.5 cc) well with area under the curve of 0.757.

Conclusions

The PCA3 score appears to stratify men based on prostatectomy tumor volume and Gleason score, and may have clinical applicability in selecting men who have low volume/low grade cancer.