Audit of prostate cancer diagnosis using P63 and prostate-specific antigen immunostains at a tertiary care hospital in South-East Nigeria

Introduction: Prostate cancer (CaP) is a leading cancer diagnosis and cause of cancer-related deaths among Nigerian men, and the accuracy of the pathologic diagnosis is critical for optimal patient care. This study aims to define the relative proportional accuracy of the histological diagnosis of prostatic cancer with hematoxylin and eosin (H and E) slides at Federal Medical Centre (FMC) Owerri, Nigeria. It also seeks to determine Gleason's grading and grade group pattern of CaP in our hospital. Materials and Methods: This study is a 5-year retrospective study reviewing all the H and E slides of prostatic Tru-Cut biopsies that were already diagnosed as cancer at FMC Owerri. These diagnoses were read and confirmed using their morphological appearance on light microscopy. Those that were suspicious, especially those that were diagnosed with well-differentiated adenocarcinoma (Gleason 3 + 3) and poorly differentiated carcinoma (Gleason 5 + 5), were sent for immunohistochemical studies. The well-differentiated carcinomas were stained for basal cells using P63, whereas poorly differentiated carcinomas were stained with prostate-specific antigens to confirm tissue of origin. These are to differentiate them from benign mimickers and metastatic carcinomas, respectively. Results: The age range of the patients was between 50 and 99 years, with a mean age of 72.84 years and peak age in the 70-79 years of age group. Using immunohistochemistry on the specimens which fitted into the criteria for immunohistochemistry, this study showed the relative proportional accuracy of the histological diagnosis of prostatic cancer using H and E to be 95.55% and the positive predictive value of H and E to be 0.83. With respect to International Society of Urological Pathology (ISUP) group grading, high-grade cancers predominated, and the most predominant grade is 5. Conclusion: H and E stain has high diagnostic accuracy (95.55%), but a 4.45% diagnostic error using H and E is quite significant. Immunohistochemistry, therefore, should act as a most valuable adjunctive, which significantly increases the diagnostic accuracy of prostatic carcinoma diagnosis.