[Model of screening for prostatic cancer among patients with prostate specific antigen concentration of 4-10 ng/ml in blood].

Screening based on the measurement of prostate specific antigen (PSA) in the blood is the basic method for early detection of prostatic cancer. However the specificity of this method even in combination with the digital rectal examination (DRE) or with PSA derivatives remains disputable in cases when PSA concentrations in the blood vary between 4 and 10 ng/ml. We evaluated the efficiency of different diagnostic methods in order to create an effective diagnostic method in patients with PSA concentrations of 4-10 ng/ml. The study was carried out in 176 patients divided into 2 groups. Group 1 consisted of 120 patients. The efficiency of DRE, PSA density, PSA transition zone density (PSAT), free to total PSA ratio, and repeated PSA (measured after antibiotic therapy in patients with prostatic inflammations) were assessed. Diagnostic methods with the highest predictive values were identified. Positive predictive values of PSAT (cut-point 0.25 ng/ml/cc), nodule and induration (revealed by DRE) were estimated as 100, 100, and 75%, respectively. Negative predictive value of repeated PSA measurement (after antibiotic therapy) was 100% with the threshold value of 4 ng/ml. Using these diagnostic methods, a model of prostatic cancer screening was created. Group 2 consisted of 56 cases. A screening model representing a combination of the above diagnostic methods with the highest predictive value was clinically tried in this group. The sensitivity of the model was 80%, specificity 94%, positive predictive value 89%, and negative predictive value 89%. Use of this model makes biopsies unnecessary in 64% cases, with the risk of undetected cancer cases no higher than 20%. Hence, the screening model based on the use of diagnostic methods with the highest predictive value effectively detects prostatic cancer among patients with PSA concentrations of 4-10 ng/ml.