Accuracy of PCA3 measurement in predicting short-term biopsy progression in an active surveillance program

PCA3 is a prostate specific noncoding mRNA that is significantly over expressed in prostate cancer tissue. Urinary PCA3 levels have been associated with prostate cancer grade and extent, suggesting a possible role in monitoring patients on active surveillance. We assessed the relationship between PCA3 and prostate biopsy results in men in a surveillance program.

Urine specimens were obtained from 294 men with prostate cancer enrolled in the Johns Hopkins surveillance program. The followup protocol included semiannual free and total prostate specific antigen measurements, digital rectal examination and annual surveillance prostate biopsy. Cox proportional hazards regression was used to evaluate the association between PCA3 results and progression on surveillance biopsy (defined as Gleason pattern 4 or 5, more than 2 positive biopsy cores or more than 50% involvement of any core with cancer).

Patients with progression on biopsy (12.9%) had a mean PCA3 score similar to that of those without progression (60.0 vs 50.8, p = 0.131). ROC analysis suggested that PCA3 alone could not be used to identify men with progression on biopsy (AUC 0.589, 95% CI 0.496-0.683, p = 0.076). After adjustment for age and date of diagnosis PCA3 was not significantly associated with progression on biopsy (p = 0.15).

In men with low risk prostate cancer who were carefully selected for surveillance the PCA3 score was not significantly associated with short-term biopsy progression. Further analysis is necessary to assess the usefulness of PCA3 in combination with other biomarkers or in selected subsets of patients undergoing surveillance.