Specificity of serum prostate-specific antigen determination in the Finnish prostate cancer screening trial

Specificity constitutes a component of validity for a screening test. The number of false-positive (FP) results has been regarded as one of major shortcomings in prostate cancer screening. We estimated the specificity of serum prostate-specific antigen (PSA) determination in prostate cancer screening using data from a randomised, controlled screening trial conducted in Finland with 32 000 men in the screening arm. We calculated the specificity as the proportion of men with negative findings (screen negatives, SN) relative to those with negative and FP results (SN/(SN+FP)). A SN finding was defined as either PSA