role of free to total prostate specific antigen [PSA] and PSA density in improving the specificty of prostate cancer screening

ABSTRACT

The diagnostic value of serum prostate specific antigen [PSA] is limited by its lack of specificity. Measurement of the free to total PSA ratio [f/t PSA] and determination of PSA density [PSAD] has been used to improve the diagnostic accuracy of PSA. A total of 122 patients above the age of 50 years with a total serum PSA ranging between 4.1 - 10.0 ng/ml were screened for prostate cancer detection. All patients were subjected to total and free serum PSA concentrations with calculation of the f/t PSA ratio, digital rectal examination [DRE], transrectal ultrasound [TRUS], determination of PSAD and TURS- guided prostatic biopsy. Prostate cancer was diagnosed in 38 patients [31.15%] while benign prostatic hyperplasia [BPH] was confirmed in 84 patients [68.85%]. Mean f/t PSA ratio was significantly lower in patients with prostate cancer compared to those wih BPH [12.89 versus 23.18, p = 0.001]. At f/t PSA cutoff point of patients with BPH would have been spared biopsy while 7.9% of cancers would be missed. Also, mean PSAD was found to be significant higher in patients with prostate cancer than those with BPH [0.32 versus 0.12, p = 0.001]. At a PSAD cutoff point of 0.15, 51.8% of patients with BPH were spared from doing biopsy while 15.8% of cancers were missed. In conclusion, measurement of the f/t PSA ratio and PSAD improves the specificity of prostate cancer screeing in selected men with total serum PSA between 4.1 - 10.0 ng/ml. and can reduce unnecessary prostatic biopsies with minimal effect on the cancer detection rate. However, further studies are warranted to confirm these findings and to define optimal cutoffs