Age-Adapted Prostate Cancer Gene 3 Score Interpretation - Suggestions for Clinical Use

The prostate cancer antigen 3 (PCA3) gene urine assay is established for biopsy decision in case of prostate cancer (PC) suspicion. Recent findings pointed to an age dependence of PCA3, with putative impact on test interpretation. However, to date no experience has been reported with regard to the extent age might modify the score in certain age ranges. Therefore, the aim of the present study was to re-evaluate the age dependency and, moreover, give suggestions for interpretation of the PCA3 score in dependence of patient's age in daily routine.

The study comprised 684 patients before prostate biopsy or prostatectomy. Post-massage voided urine samples were assessed by PCA3 measurement. PCA3 scores were correlated to patient's age. The collective was divided into four subcollectives by quartiles of age distribution. For every subcollective the cutoff value at specificity of ≥ 60 was determined. Results were classified by age-class specific cutoff values and test qualities were compared at different cutoffs.

In the collective, 59.1% of patients had a positive biopsy. PCA3 correlated to patient's age in univariate and multivariate analysis (p < 0.001 each). The division into age subcollectives revealed groups < 60, 60 - 65, 66 - 69 and > 69 years. Median PCA3 values of patients without/with PC were 17/32, 27/42, 34/55 and 52/68 in the four age classes. Cutoff values for which specificity was determined with ≥ 60 were 23, 39, 42, and 65. Constant cutoff values showed lower sensitivities in younger and lower specificities in older patients. Only the age adjusted values revealed an improved performance with PPV 68.7, accuracy 59.5 and sensitivity 57.7 at specificity of 62.1% in the whole cohort.

The study confirms that the PCA3 score increases with age. The recommended cutoff score of 35 is suitable especially for patients aged in their sixties. Lower reference values between 20 and 30 have to be taken into account in patients aged < 60 years and higher values around 40 to 50 may point to suspicion for PC in patients > 69 years. These results may further improve the diagnostic performance of the PCA3 test and keep the PCA3 test as a significant test in PC diagnostics along with new upcoming urine markers.