Immunohistochemical Analysis of Prostein Expression in Archived Prostatic Core Biopsies from Prostate Cancer Patients in Western Kenya

Background Prostate cancer is the leading cause of cancer-associated mortality in men. Most of the current biomarkers for detection of the disease have low sensitivity and specificity. Prostein is a newly reported prostate cancer biomarkers whose diagnostic utility can help in early detection of the disease. Nonetheless, previous studies have utilized limited number of samples to evaluate its immunohistochemistry (IHC) and reports on the African population are not available. The current study aimed to determine the prostein expression in archived prostatic core biopsies from prostate cancer patients in Western Kenya. Materials and Methods This was a retrospective study conducted on malignant and benign prostatic tissue core biopsies of 106 patients who underwent prostate core biopsy at Jaramogi Oginga Odinga Teaching and Referral Hospital and division of urology at Synergy Clinics, Kisumu between January 2018 to May 2021. Immunohistochemical technique was performed on each of the 106 samples and on the following non-prostatic male control biopsies; Testis, Penis, Liver and Esophagus. Cellular location of prostein staining was evaluated at X40, X100 and X400 magnification using a light microscope and was classified as cytoplasmic or nucleocytoplasmic. Intensity of prostein expression was assessed for each core biopsy at similar magnification and graded according the immunohistochemistry composite score. Results The biopsies had been obtained from men whose mean (SE) age was 72.00±0.93 years. 95.3% (101) of the biopsies were malignant and 4.7% (5) were benign. Four non-prostatic male tissues were included. 97% of malignant and all the benign prostate tissue stained positive for prostein whereas the four non-prostatic male tissues were negative. Staining intensities were weak (24.5%), Moderate (17.0%), strong (55.7%) and non-stained (2.8%). The staining was highly immunolocalized within the cytoplasm (95.1% cases) as compared to nucleocytoplasmic (2.0% cases). The mean immunoreactivity composite score was 1.91±0.96 (0.0-3.14). Strongly stained sections had a punctate plasma membrane staining pattern clustered within the cytoplasm in a perinuclear location whereas the weakly stained sections had faint and punctate coarse brown cytoplasmic granular appearing. Conclusion Prostein is exclusively expressed in benign and malignant prostate tissue with a higher cytoplasmic granular staining pattern in the present population. These findings suggest that prostein diagnostic utility is applicable in the current study population and routine IHC diagnosis of prostate cancer may be recommended.