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External Validation of the Prostate Cancer Risk Calculator
David J Hernandez*1, Misop Han1, Elizabeth B Humphreys*1, Leslie A Mangold*1, Michael K Brawer*2, Samir S Taneja*3, Stacy J Childs*4, Thomas A Stamey*5, Alan W Partin1
1Johns Hopkins Medical Institutions, Baltimore, MD;2Northwest Prostate Institute, Seattle, WA;3New York University School of Medicine, New York, NY;4Cheyenne Urological, Cheyenne, WY;5Stanford University School of Medicine, Stanford, CA
Introduction: The decision for prostate biopsy may be aided by algorithms that estimate an individual's risk of having prostate cancer (PCa) detected. Investigators from the PCPT developed a risk calculator based on age, race, PSA, DRE, family history, and history of a prior negative prostate biopsy. We externally validated this risk calculator and compared its performance to PSA alone.
Methods: We used data from two prospective multicenter clinical trials studying complexed and percent-free PSA, respectively, on 1,108 men scheduled for biopsy who had all relevant clinical and pathologic data available and no previous diagnosis of cancer. Using the risk equations formulated from the inverse logistic functions previously published, we calculated the risks of PCa and of high grade PCa (Gleason ≥7) for each patient. Receiver operating characteristics (ROC) curves for the risk calculator and for PSA were generated and compared.
Results: PCa was detected in 394 (35.6%) and 155 (14.0%) had PCa with Gleason ≥7. For PCa prediction, the ROC analysis showed an area under the curve (AUC) for the risk calculator of 0.67, statistically greater than the AUC for PSA of 0.62 (p= 0.0002). For predicting high grade PCa, the AUCs were 0.74 and 0.71 for the risk calculator and PSA, respectively (p= 0.024).
Conclusions: Though the difference in AUCs for the risk calculator and PSA is statistically significant, the ROC analyses reveal that the addition of age, race, DRE, FMHx, and previous negative biopsy history only results in a modest improvement in the performance characteristics of PSA alone.
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