Four-kallikrein PSA panel predicts likelihood of prostate cancer after negative biopsy
MedWire News: Research results suggest that adding a panel of four kallikrein markers to a prostate cancer prediction model could greatly reduce the number of unnecessary biopsies undertaken in men with elevated prostate-specific antigen (PSA) levels after a previously negative biopsy.
The model, including total, free, and intact PSA, and human kallikrein-related peptidase-2 measurements, as well as age and digital rectal examination (DRE) results, was better able to predict which patients would have prostate cancer at second biopsy, than a model including age, DRE, and total PSA alone.
On the basis of the findings, Hans Lilja from the Memorial Sloan-Kettering Cancer Center in New York, USA, and colleagues report that use of the model "would dramatically reduce rebiopsy rates, while delaying the diagnosis of only a small number of cancers, almost all of which are low grade."
The researchers evaluated the accuracy of the prediction model with and without the four kallikrein markers using data for 925 participants of the European Randomized study of Screening for Prostate Cancer. The men all underwent a second prostate biopsy prompted by a PSA level of 3 ng/ml or above, after an initial negative biopsy.
The full-kallikrein model had a higher discriminative accuracy than age, PSA, and DRE alone with an area under the receiver operating characteristic curve (AUC) score of 0.68 versus 0.58, respectively. It also more accurately predicted high-grade cancer (Gleason score 7 or higher) at an AUC of 0.87 versus 0.76.
The researchers estimated that using a cancer risk threshold of 15% to initiate biopsy, the full-kallikrein model would have reduced the number of repeat biopsies undertaken among 1000 men by 712.
Furthermore, just 53 cancers would have been missed (or delayed), only three of which would have been Gleason score 7, and the rest Gleason score 6 or less.
"Biopsying all men with previous negative biopsies will lead to a large number of unnecessary biopsies and detection of a large number of potentially clinically insignificant cancers," write Lilja et al in the British Journal of Cancer.
They conclude: "Thus, use of such models may decrease the overdiagnosis and overtreatment associated with repeated screening and repeat biopsy in men with previous negative biopsies."
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By Sarah Guy