Expression of Prostate-specific Membrane Antigen in Prostatic Carcinoma and its Correlation with Gleason Score and Grade Grouping: A Cohort Study

Introduction: Prostate-Specific Membrane Antigen (PSMA), a transmembrane glycoprotein, has emerged as a promising biomarker due to its selective presence in prostate tissue, particularly in prostatic carcinoma. This has been extensively studied in imaging to assess tumour aggressiveness to aid in treatment planning. Aim: To study the Immunohistochemical (IHC) expression of PSMA in prostatic carcinoma and to correlate PSMA expression with Gleason Score (GS) and grade grouping. Materials and Methods: The present cohort study was conducted over two years (May 2022 to April 2024) at the Department of Pathology, Kalinga Institute of Medical Sciences, Bhubaneswar, Odisha, India. A total of 63 cases of prostatic adenocarcinoma were included; the PSMA expression was performed and correlated with clinicopathological parameters such as age, nature of specimen, location of tumour and serum Prostate-Specific Antigen (PSA) level. Statistical analysis such as mean, percentage, Standard Deviation (SD), Chisquare test was used as a test of association. The Spearman’s Rho Correlation test was used to establish correlation of the parameters with PSMA expression. All tests were performed using Statistical Package for Social Sciences (SPSS), version 26.0. Results: The PSMA expression was higher in cases with higher GSs (33 cases with GS >7) and Grade group (24 cases with Grade group 5) and the correlation was statistically significant for both (r=0.403, p-value=0.014 and r=0.391, p-value=0.016, respectively). The PSMA expression did not correlate with age (r=0.118, p-value=0.205) serum PSA levels (r=0.088, p-value=0.643), and with Peri-Neural Invasion (PNI) (r=-0.139, p-value=0.486). The study showed a 0.7 fold increase in disease recurrence after curative therapy using the Kaplan-Meier curve analysis. Conclusion: A significant overexpression of PSMA in prostatic carcinoma suggests its potential as a diagnostic and prognostic marker. High PSMA expression was seen in prostatic carcinoma with higher GS and Grade group in this study. Thus, high PSMA expression is associated with poor prognosis and disease recurrence. Following curative therapy for prostate carcinoma, PSMA can predict disease recurrence and is an independent prognostic marker on biopsies. This study proposes the use of the immunohistochemical marker PSMA for differentiating between indolent and severe disease and further categorising into low risk and high-risk patients.