Blood biomarkers could dramatically reduce prostate biopsy rates
MedWire News: Research results show that testing levels of free and intact prostate-specific antigen (PSA) and kallikrein-related peptidase 2 (hK2) in addition to total PSA, can successfully predict the result of prostate biopsy in men with raised PSA levels.
The research team believes that introducing this panel of four kallikreins into clinical practice could dramatically reduce the number of prostate biopsies carried out after PSA screening, sparing men physical discomfort, and potentially reducing the risk for overdiagnosis of prostate cancer.
“Our models can be used to determine which men should be advised to have biopsy and which might be advised to continue screening but defer biopsy until stronger evidence of malignancy exists,” write Andrew Vickers, from Memorial Sloan-Kettering Cancer Center in New York, USA, and colleagues in the Journal of Clinical Oncology.
The study cohort included 2914 previously unscreened men from the Rotterdam arm of the European Randomized Study of Screening for Prostate Cancer, who underwent prostate biopsy as a result of having a PSA level of 3 ng/ml or above. In all, 807 men were diagnosed with prostate cancer.
The researchers assessed the men’s biopsy outcomes to compare the predictive accuracy of the laboratory base model (PSA and age), and the full laboratory model (age plus four kallikrein markers).
Using area under the curve (AUC) analysis, the base model predicted prostate cancer with a sensitivity of 0.64 where 1.00 is perfect discrimination, which increased to 0.76 using the full laboratory model.
After incorporating digital rectal examinations into the analysis, sensitivity increased to 0.70 for the base model, and 0.78 for the full model.
“The enhancements of the full models to base models to predict any cancer were statistically significant,” note Vickers and team.
They next applied the full laboratory model to a hypothetical cohort of 1000 men, which revealed that if biopsies were only undertaken in men with a predicted probability for prostate cancer of 20% or higher, 513 less biopsies would be undertaken per 1000 men with an elevated PSA.
Furthermore, 54 of 177 low-grade cancers and 12 of 100 high-grade cancers would be missed using this model, which the researchers believe “are exactly the type of cancers thought to constitute overdiagnosis.”
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By Sarah Guy