The Diagnostic Accuracy of Prostate-Specific Antigen and Digital Rectal Examination in the Diagnosis of Prostate Cancer at the University of Benin Teaching Hospital.

OBJECTIVES

To assess and compare the diagnostic accuracy of prostate-specific antigen (PSA) and digital rectal examination (DRE) in the diagnosis of prostate cancer.

MATERIALS AND METHODS

It was a prospective, comparative study carried out over a period of 14 months at the University of Benin Teaching Hospital, Benin City. It involved male patients ≥50 years who presented at the urology clinic with lower urinary tract symptoms (due to prostatic disease), PSA > 4 ng/mL and or abnormal DRE findings. They had serum total PSA determined. Patients were recruited for prostate biopsy and samples sent for histopathological assessment. Histopathology was determined by a histopathologist dedicated to the study. Using a researcher-administered, structured proforma, data were collected, collated and subjected to statistical analysis for assessment and comparative analysis of the diagnostic accuracy of PSA and DRE.

RESULTS

The study involved 94 patients; they were all Nigerians. The age range of the study population was 50-85 years, with a mean age of 70.4 ± 8.6 years. Most (89.4%) of the patients were exposed to formal education. PSA of the study population ranged between 2.5 and 840 ng/mL. For patients with carcinoma of the prostate (CaP), median PSA value was 79.2 ng/mL, whereas patients with benign prostatic disease had a median PSA value of 16.0 ng/mL. The difference in median PSA value between the two groups was statistically significant ( < 0.001). In this study, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy of PSA was 97.2%, 12.1%, 40.7%, 87.5% and 44.7%, respectively. However, a sensitivity, specificity, PPV, NPV and diagnostic accuracy of DRE was 88.9%, 70.7%, 65.3%, 91.1% and 77.7%, respectively. Combination of PSA and DRE had sensitivity, specificity, PPV, NPV and diagnostic accuracy of 91.7%, 91.4%, 86.8%, 94.6% and 91.5%, respectively. In this study, 36 (38.3%) patients had CaP whereas 57 (60.6%) patients had benign prostatic disease and 1 (1.1%) patient had high-grade prostatic intraepithelial neoplasia.

CONCLUSION

The study revealed a low specificity, high sensitivity and low diagnostic accuracy of PSA in diagnosis of CaP. However, sensitivity, specificity, and diagnostic accuracy of DRE were high but not sufficient in diagnosis of CaP. A combination of PSA and DRE had a higher sensitivity, specificity and diagnostic accuracy in diagnosis of prostate cancer.