The relationship between Prostate CAncer gene 3 (PCA3) and prostate cancer significance.

OBJECTIVE

To evaluate the relationship between Prostate CAncer gene 3 (PCA3) and prostate cancer significance.

PATIENTS AND METHODS

Clinical data from two multi-centre European open-label, prospective studies evaluating the clinical utility of the PCA3 assay in guiding initial and repeat biopsy decisions were analysed. First-catch urine was collected after digital rectal examination (three strokes per lobe) and the PCA3 score was determined using the PROGENSA(®) PCA3 assay. Transrectal ultrasound-guided biopsy (≥8 cores) and radical prostatectomy (RP) specimens were analysed by the local pathologist. The relationship between biopsy and RP outcomes with the PCA3 score was assessed.

RESULTS

Of the 1009 men enrolled, 348 (34%) had a positive biopsy. The median and mean PCA3 scores were statistically significantly lower in men with biopsy Gleason score <7 vs ≥7, with clinical stage T1c vs T2a-T2c, T3a cancers, with ≤33% vs >33% positive biopsy cores and with 'biopsy indolent' vs 'biopsy significant' prostate cancer (indolent prostate cancer defined by biopsy Epstein criteria). In all, 175 men with a positive biopsy had a RP: median and mean PCA3 scores were statistically significantly lower in men with pathological Gleason score <7 vs ≥7, and with pathological stage T2a-T2c vs T3a-T3b cancers.

CONCLUSIONS

The PCA3 score may combined with traditional tools aid in identifying men with clinically insignificant prostate cancer, as shown by biopsy and RP pathological features including biopsy Epstein criteria, who could be candidates for active surveillance. Treatment selection should be based on a combination of clinical and pathological variables. If one wants to use a threshold point to guide treatment decisions in clinical practice, a PCA3 score threshold of 20 may have the highest utility for selecting men with clinically insignificant prostate cancer in whom active surveillance may be appropriate; a PCA3 score threshold of 50 may be used to identify men at high risk of harbouring significant prostate cancer who are candidates for RP. Although the association between the PCA3 score and prostate cancer aggressiveness needs further evaluation, the inclusion of the PCA3 score into patient management strategies may provide clinicians with another tool to more accurately determine the course of treatment.