Comparative Analysis of the Gleason Grading System and Its Revisions Against Alternative Grading Systems in Predicting Prostate Cancer Outcomes: A Systematic Review

Introduction: Developed in the ۱۹۶۰s, the Gleason grading system has played a vital role in assessing prostate cancer (PCa), providing valuable information about the aggressiveness of tumors. This comprehensive analysis investigated the Gleason system and its revisions and compared them with alternative grading methods in terms of their predictive value. Methods: A qualitative synthesis method was utilized for this purpose. A thorough literature search was performed across multiple databases, including PubMed, Scopus, Web of Science, and Embase. In addition, the search focused on articles published between ۲۰۱۴ and ۲۰۲۴ that examined the Gleason grading system, its revisions, and comparisons with other grading methods. Adhering to PRISMA guidelines, researchers identified ۱۷ studies that met the predetermined inclusion and exclusion criteria for analysis. Results: Despite its limitations in classifying certain histological subtypes, the Gleason grading system has remained the preferred standard due to its practical application and flexibility. The International Society of Urologic Pathology (ISUP) modifications in ۲۰۰۵ and ۲۰۱۴ improved prognostic accuracy by implementing grade groups and refining evaluation techniques. Based on the findings, the ongoing relevance of the Gleason system is evident compared to molecular grading systems and the tumor, node, metastasis (TNM) staging system. However, supplementary methods contribute to a more comprehensive cancer evaluation. Conclusion: Despite the emergence of new grading methods, the Gleason system remains crucial for evaluating PCa. The enduring significance of this system stems from its straightforward approach, consistent results, and clinical relevance. Recent updates to the system have reinforced its importance in contemporary oncology practice.