MedWire News: Men with rapid increases in prostate-specific antigen (PSA) velocity - the rate at which prostate-specific antigen levels change over time - should not be recommended for biopsy in the absence of other prostate cancer indicators, say US researchers.
Their study shows that adding PSA velocity to an existing model of standard pre-biopsy prostate cancer indicators does not improve predictive accuracy in any significant way.
"Our findings suggest that men with a sudden large rise in PSA should be carefully evaluated for benign disease, possibly including a repeat PSA, before referral for prostate biopsy," report Andrew Vickers, from the Memorial Sloan-Kettering Cancer Center in New York, USA, and co-authors.
Thus, the team recommends that the current inclusion of PSA velocity in National Comprehensive Cancer Network (NCCN) guidelines be reconsidered.
"We found no reason to believe that implementation of the guideline would improve patient outcomes; indeed, its use would lead to a large number of unnecessary biopsies," the researchers write in the Journal of the National Cancer Institute.
Using a subset of 5519 men from the Prostate Cancer Prevention Trial, all of whom underwent an end-of-trial biopsy irrespective of PSA level, Vickers and colleagues assessed the ability of PSA velocity to predict the presence of prostate cancer.
After incorporating PSA velocity into a model including age, log PSA at biopsy, family history of prostate cancer, digital rectal examination (DRE), and whether a patient had a previous biopsy, the area under the receiver operating characteristic curve (AUC) score - indicating predictive accuracy - increased by only 0.007, from 0.702 to 0.709.
The NCCN recommendation that men with a PSA velocity above 0.35 ng/ml/year should receive a biopsy, even if they have a normal DRE and a PSA level below the cut-point of 4 ng/ml, would lead to detection of 115 additional cancers, but 433 unnecessary biopsies in this cohort, calculate the researchers.
Furthermore, the predictive accuracy of PSA velocity compared with PSA level alone was only mildly better, with an AUC of 0.692 compared with 0.682.
"In other words, if a clinician feels that the current PSA thresholds are insufficiently sensitive, he or she would be better off identifying patients to biopsy by using low PSA thresholds than by adding PSA velocity as a criterion for biopsy," say Vickers et al.
Commenting on the findings, editorialists Siu-Long Yao and Grace Lu-Yao (Cancer Institute of New Jersey, New Brunswick, USA) say the results "remind us that the use of PSA as a screening tool still leaves much to be desired."
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