Diagnostic Value of Prostate Specific Antigen and Its Density in Iranian Men with Prostate Cancer

Background: The specific threshold for prostate-specific antigen and density (PSA, PSAD) to delineate which patients are at the highest risk has been controversial. The purpose of this study was to evaluate the diagnostic value of PSA and PSAD in Iranian patients with prostate cancer. Methods: Three hundred men with the serum PSA greater than 4.0 ng/ml, abnormal digital rectal examination and/or suspicious transrectal ultrasound underwent transrectal ultrasound-guided prostate biopsies. PSAD was calculated by dividing the serum PSA in ng/ml by the volume of the entire prostate in cm(3). Correlation with Gleason grade of the tumor was also made. The patients were divided into three groups according to their PSA values. The receiver operator characteristic (ROC) curve was produced from the raw data on all patients. Results: One hundred and two patients showed a cancer rate of 34%. The mean PSA and PSAD of the cancer group were significantly higher than those of the non-cancer group with better performance of PSAD as confirmed by ROC curve. In patients with PSA levels between 4 and 10 ng/ml, mean PSAD values in positive and negative biopsy groups showed a significant difference while mean PSA values between these biopsy groups revealed no significant difference. The PSAD cutoff of more than 0.1 had higher sensitivity than 0.15 at the expense of increasing the number of unnecessary biopsies. Among those the patients with PSA levels above 10ng/ml, both mean PSA and PSAD values of positive and negative biopsy groups had significant differences. The sensitivity of PSAD cutoff of 0.1 was not significantly higher than 0.15 while PSAD of 0.15 showed a higher specificity. PSAD > 0.15 missed cancer in 18 out of 102 patients, nearly half of those with clinically significant mid and high grade cancers. Conclusion: Overall, PSAD is a better diagnostic tool for the detection of prostate cancer than PSA, especially in patients with PSA between 4 and 10ng/ml. PSAD cutoff of 0.15 is not inclusive enough in patients with PSA levels between 4 and 10ng/ml and we propose PSAD of 0.1 as a better threshold for prostate biopsy in men with PSA at this range to detect clinically important cancers. Also, we recommend transrectal ultrasound guided biopsy in any patient with PSAD greater than 0.15 and PSA more than 4 ng/ml.