The Comparison of Percent Free PSA with total PSA in the diagnosis of Prostate Cancer

Objective: To determine the ratio of free to total PSA in patients ' of carcinoma prostate and nodular hyperpla-sia, and to compare this ratio with total PSA for diagnosis of prostate cancer. Settings: The study was conducted in Armed Forces Institute of Pathology (AFIP) Rawalpindi in collaboration with Armed Forces Institute of Urology (AFIU) Rawalpindi, over a period of 7 months (February 2000 to August 2000). Materials and Method: One hundred and seventy nine blood samples were collected from patients admitted for prostatectomy. After surgery, diagnosis of prostate carcinoma or nodular hyperplasia was confirmed histological-ly. Serum samples were analyzed for total and free PSA. Results: The ± 2SD values of total PSA for nodular hyperplasia were 4.07-13.93 ng/ml (mean = 9.00 ng/ml), and for carcinoma prostate were 9.34-23.74 ng/ml (mean = 16.54 ng/ml).These values showed a considerable over-lap. While 95 % confidence interval values of percent free PSA for nodular hyperplasia were 14.00- 28.08% (average = 21.04%), and for carcinoma prostate were 2.69-16.05 % (average = 9.37%) and these values showed a little overlap. The sensitivity of percent free PSA in differentiating between prostate carcinoma and nodular hyperplasia was 96 % with a cut off limit of 15 % of % free PSA as compared to 74 % with total PSA alone. Conclusion: Percent free PSA is a better marker for differentiating patients of carcinoma prostate from nodular hyperplasia as compared to total PSA (JPMA 53:233;2003)