Background: A direct correlation between the preoperative prostate cancer antigen 3 (PCA3) gene and total tumor volume in postprostatectomy specimens has recently been reported. This suggests that the PCA3 score could serve as a surrogate for tumor burden in patients with prostate cancer. Accordingly, the PCA3 density (that is, the ratio of the PCA3 score to prostate volume) is representative of the degree of prostate volume occupied by tumor.
Objective: To show that the PCA3 density would be directly related to the likelihood of finding cancer on prostate biopsy, given that larger tumors in smaller glands would be more likely to be detected through prostate biopsy.
Methods: We identified 288 men referred for prostate biopsy for an elevated prostate-specific antigen (PSA) level, high PSA velocity, low free- to total-PSA ratio, or suspicious digital rectal exam. All of the patients had had a urinary PCA3 test performed no more than 4 weeks before biopsy, and prostate volume was recorded by transrectal ultrasound determination at the time of biopsy. The diagnostic yield of PSA level, PSA density (PSAD), PCA3 score, and PCA3 density in detecting cancer was evaluated using a receiver operating characteristic (ROC) curve.
Results: Of the 288 patients included for analysis, 183 (63.5%) underwent an initial prostate biopsy and 105 (36.5%) had at least 1 previous negative biopsy. Cancer was detected in 74 (25.7%) patients. The area under the curve was 0.486 for PSA level, 0.590 for PSAD, 0.687 for PCA3 score, and 0.717 for PCA3 density.
Conclusion: PCA3 density is strongly correlated with cancer detection and may be useful in selecting patients for biopsy.
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