Expression of Phosphatase-Tensin Homolog and Erythroblast Transformation-Specific Related Genes in Prostate Carcinoma Cases Seen at Osun State University Teaching Hospital, Osogbo, Osun State, Nigeria: A 5-Year Retrospective Observational Study

Background: Prostate carcinoma is the second most common cancer in men worldwide and a leading cause of cancer-related mortality, particularly in low- and middle-income countries. Prognostic assessment relies largely on International Society of Urological Pathology grading, which has recognized limitations. Molecular alterations, including phosphatase and tensin homolog (PTEN) loss and ETS-related gene (ERG) rearrangements, contribute to prostate carcinogenesis. This study aimed to evaluate immunohistochemical expression of PTEN and ERG across low-, intermediate-, and high-grade prostate carcinomas diagnosed at UNIOSUN Teaching Hospital, Osogbo, Nigeria.Materials and Methods: This retrospective observational study included 70 histologically confirmed prostate carcinoma cases diagnosed between January 2017 and December 2021. Formalin-fixed, paraffin-embedded tissue blocks were stained with monoclonal antibodies against PTEN and ERG. PTEN positivity was defined as >10% combined nuclear and cytoplasmic tumor staining, and ERG positivity was defined as strong nuclear staining in >20% of tumor cells. Associations between biomarker expression and tumor grade were assessed using the chi-square test (p<0.05).Results: Prostate carcinoma accounted for 13.3% (102 of 768) of all male solid tumors during the study period. The mean age of analyzed cases was 72.9±9.1 years (range, 47–91 years). PTEN loss was observed in 25.7% (18 of 70) of cases and was most frequent in high-grade tumors (51.6%, 16 of 31; p=0.001). ERG expression was not detected in any case, although internal and external controls stained appropriately.Conclusion: PTEN loss was significantly associated with high-grade prostate carcinoma, supporting its potential role as an adjunct prognostic biomarker. The absence of ERG expression may reflect populationspecific molecular patterns or archival tissue limitations and warrants further investigation.