Prostate Specific Antigen Density (PSAD) as a predictor of prostate cancer in patients with PSA in the grey zone at Mulago Hospital

Abstract

Background: Prostate specific Antigen (PSA) elevation has been one of the parameter used in the assessment of patients for prostate biopsy. However PSA is organ-specific but not cancer-specific. And since prostatic biopsy is an invasive procedure there is a need to have a test that will increase prostate cancer catch rate while reducing unnecessary biopsies. Several derivatives of PSA have been developed to increase the ability of PSA to predict prostate cancer these includes PSAD, PSA velocity and %FPSA. Objective: To determine the proportion of patients with prostate cancer and establish the PSAD threshold for prostatic biopsy in patients with gray zone PSA level at Mulago Hospital, Kampala Uganda. Methods: Ethical considerations were adhered to. A Cross Sectional Study involving 88 participants with ages 40 years and above and PSA levels between 2.5 – 10 ng/ml were recruited consecutively. Patients with enlarged suspicious prostate gland on DRE were included. Eligible patients were sent for volume estimation using abdominal ultrasonography and prostate biopsies done. The PSA density threshold for diagnosis of prostate cancer was determined then using receiver operating characteristic (ROC) curve analysis. Results: The mean age was 68.9 years with a standard deviation of 9.6. Proportion of participants with cancer of the prostate in the gray zone is 16 (18.2%). Median prostate volumes were 107cc (78.5 – 144.3) in cancer group and 74cc (56 – 131) in non cancer group. In this study PSAD threshold for prostatic biopsy was determined to be 0.06ng/ml/cc. Conclusion: From this study PSAD threshold for prostatic biopsy was low at 0.06 and poorly discriminated patients with prostate cancer from those without. This is explained by the fact that most of the study participants had larger prostate volumes.