The diagnostic accuracy of combined prostate-specific antigen (PSA) and digital rectal examination (DRE) in prostate cancer in Northern Tanzania

Abstract

Background: Prostate-Specific Antigen (PSA) is a common screening tool for prostate cancer (PCa), with reported low specificity. PSA combined with digital rectal examination (DRE) could lead to earlier identification of PCa, reducing the associated morbidity and mortality. This study sought to evaluate the performance of PSA in combination with DRE in the diagnosis of PCa among symptomatic patients in Tanzania.

Methods: A cross-sectional study was conducted at Kilimanjaro Christian medical center (KCMC) referral hospital in Northern Tanzania. A total of 200 men attending the out-patient urology clinic with bladder outlet obstruction were enrolled from July 2018 to September 2019. Histopathology, DRE, PSA, a combination of all three tests and were analysed. Diagnostic sensitivity, specificity, positive (PPV) and negative predictive values (NPV) of PSA and DRE were estimated against histopathology as the reference test.

Results: Of the 200 study participants, 50 agreed to trucut biopsy. The proportion of patients diagnosed with prostate cancer by histopathology was 40% (20/50). The sensitivity of DRE alone was 75%, specificity 46.7%, PPV 48.4% and NPV, 73.7%. The PSA alone had a sensitivity of 90%, specificity 46.7%, PPV 52.9%, and NPV, 87.5%. PSA combined with DRE had a sensitivity of 90.0%, specificity 36.7%, PPV 48.6%, and NPV 84.6% when evaluated against histopathology.

Conclusion: PSA combined with DRE shows better detection accuracy for PCa compared to the use of PSA or DRE alone. This combined approach could significantly improve the early and definitive detection of PCa in symptomatic adult males in Tanzania.