Delta Prostate Specific Antigen (PSA) Helps to Predict Prostate Cancer in Men with Serum PSA Level above 4 ng/ml

Park, Bong Hee; Park, Jeong Seon; Park, Kyung Soo; Park, Jong Kwan

Abstract

PURPOSE: Prostate biopsies have typically been performed on all patients with prostate specific antigen (PSA) levels above 4 ng/ml, however, the cancer detection rate is low. We would like to predict cancerous conditions of the prostate by developing a new PSA formula.
MATERIALS AND METHODS
Between July 2004 and July 2006, 93 patients with serum PSA levels above 4 ng/ml received extended prostate biopsies. The medical records of all patients - age, total/free PSA after/before prostate massage, final diagnoses of prostate biopsies - were reviewed retrospectively. We developed a new formula to calculate the delta PSA: (total/free PSA after prostate massage - total/free PSA before prostate massage) / total/free PSA before prostate massage.
RESULTS
The patients were divided into two groups, the prostate cancer group (39 patients) and the benign disease group (54 patients). Mean total/free PSA for the benign disease group were 9.35/1.49 ng/ml (before) and 16.66/5.06 ng/ml (after), while values for the data of prostate cancer group were 21.02/2.43 ng/ml (before) and 24.61/4.40 ng/ml (after). The positive predictive value of the patients with PSA levels between 4 and 10 ng/ml was 32%; the positive predictive value of the patients with PSA levels above 10 ng/ml was 75%. The mean delta total/free PSA values for the benign disease and prostate cancer groups were 0.92/2.42 and 0.28/1.14, respectively. The cut off value of delta total/free PSA was below 0.5/2.0. Sensitivity, specificity, and positive predictive values for delta total PSA were 90% (95% confidence interval (CI), 80.2~99.3), 54% (95% CI, 41.4~67.7) and 58% (95% CI, 45.9~70.8), respectively. Sensitivity, specificity, and positive predictive values based on delta free PSA were 87% (95% CI, 76.7~97.7), 48% (95% CI, 36.7~63.3), and 56% (95% CI, 43.3~68.2), respectively.
CONCLUSIONS
We suggest that the use of delta total/free PSA in patients with serum PSA levels above 4 ng/ml may be helpful, not only to better detect prostate cancer, but also to reduce unnecessary prostate biopsies.