Biochemical Basis and Clinical Application of Tumour Markers in Prostate Cancer Screening in Oyo State

Prostate cancer is the most common male malignancy in Nigeria, and prostate-specific antigen (PSA) remains the most clinically utilised tumour marker in its detection. This study evaluates the biochemical basis and clinical application of PSA and related markers including free PSA, PSA density, and PSA velocity in prostate cancer screening at a urology clinic in Oyo State, South West Nigeria. A cross-sectional analytical design was employed, recruiting 200 men aged 40 years and above who presented for prostate health evaluation. Total and free PSA were measured by ELISA, and PSA density was calculated using transrectal ultrasound-measured prostate volume. Prostate biopsy results, where available, were used as the diagnostic reference standard. The sensitivity, specificity, and area under the receiver operating characteristic curve for each PSA parameter were calculated. The study also explores the effect of benign prostatic hyperplasia and prostatitis on PSA levels in this population. Findings will support evidence-based refinement of prostate cancer screening algorithms applicable to Nigerian urological practice. Keywords: prostate-specific antigen, PSA, prostate cancer screening, tumour markers, Oyo State.