Clinical utility of the PCA3 urine assay in European men scheduled for repeat biopsy

Prostate cancer gene 3 (PCA3): development and internal validation of a novel biopsy nomogram

BACKGROUND

Urinary prostate cancer gene 3 (PCA3) represents a promising novel marker of prostate cancer detection.

OBJECTIVE

To test whether urinary PCA3 assay improves prostate cancer (PCa) risk assessment and to construct a decision-making aid in a multi-institutional cohort with pre-prostate biopsy data.

DESIGN, SETTING, AND PARTICIPANTS

PCA3 assay cut-off threshold analyses were followed by logistic regression models which used established predictors to assess PCa-risk at biopsy in a large multi-institutional data set of 809 men at risk of harboring PCa.

MEASUREMENTS

Regression coefficients were used to construct four sets of nomograms. Predictive accuracy (PA) estimates of biopsy outcome predictions were quantified using the area under the curve of the receiver operator characteristic analysis in models with and without PCA3. Bootstrap resamples were used for internal validation and to reduce overfit bias. The extent of overestimation or underestimation of the observed PCa rate at biopsy was explored graphically using nonparametric loss-calibration plots. Differences in PA were tested using the Mantel-Haenszel test. Finally, nomogram-derived probability cut-offs were tested to assess the ability to identify patients with or without PCa.

RESULTS AND LIMITATIONS

PCA3 was identified as a statistically independent risk factor of PCa at biopsy. Addition of a PCA3 assay improved bootstrap-corrected multivariate PA of the base model between 2% and 5%. The highest increment in PA resulted from a PCA3 assay cut-off threshold of 17, where a 5% gain in PA (from 0.68 to 0.73, p=0.04) was recorded. Nomogram probability-derived risk cut-off analyses further corroborate the superiority of the PCA3 nomogram over the base model.

CONCLUSIONS

PCA3 fulfills the criteria for a novel marker capable of increasing PA of multivariate biopsy models. This novel PCA3-based nomogram better identifies men at risk of harboring PCa and assists in deciding whether further evaluation is necessary.

Insignificant prostate cancer and active surveillance: from definition to clinical implications

CONTEXT

Due to early detection strategies, prostate cancer is diagnosed early in its natural history. It remains unclear whether all patients diagnosed with prostate cancer warrant radical treatment or may benefit from delayed intervention following active surveillance.

OBJECTIVE

A systematic review of active surveillance protocols to investigate the inclusion criteria for active surveillance and the outcome of treatment.

EVIDENCE ACQUISITION

Medline was searched using the following terms: prostate cancer, active surveillance and expectant management for dates up to October 2008. Further studies were chosen on the basis of manual searches of reference lists and review papers.

EVIDENCE SYNTHESIS

Numerous studies on active surveillance were identified. The recent inclusion criteria of the studies are rather similar. Keeping the short follow-up of all studies in mind, the majority of men stay on active surveillance, and the percentage of patients receiving active treatment is as high as 35% of all patients. Once a patients requires active treatment, most patients still present with curable prostate cancer. Furthermore, only few deaths due to prostate cancer have occurred.

CONCLUSIONS

Active surveillance is an alternative option to immediate treatment of men with presumed insignificant prostate cancer. It seems that criteria used to identify men with low-risk prostate cancer are rather similar, and immediate treatment of men meeting these criteria may result in an unnecessary number of treatments in these highly selected patients. Data from randomised trials comparing active surveillance and active treatment will provide additional insight into outcome and follow-up strategies.