ROLE OF BACILLUS CALMETTE–GUÉRIN (BCG) IN NON-MUSCLE INVASIVE BLADDER CANCER (NMIBC)

Introduction: Non-muscle invasive bladder cancer (NMIBC) represents approximately 70–75% of newly diagnosed bladder cancers and is associated with high recurrence and progression rates. Intravesical Bacillus Calmette–Guérin (BCG) immunotherapy remains the gold standard adjuvant treatment for intermediate- and high-risk NMIBC due to its significant antitumor efficacy (1,2). Objective: To review the role, mechanism of action, clinical efficacy, indications, and limitations of intravesical BCG therapy in the management of non-muscle invasive bladder cancer. A narrative review of published literature, clinical guidelines, randomized trials, and review articles related to BCG therapy in NMIBC was conducted using indexed medical databases. Relevant studies focusing on immunological mechanisms, treatment protocols, therapeutic outcomes, and adverse effects were included (1–15). Result: BCG therapy exerts its antitumor effect through activation of both innate and adaptive immune responses. Following intravesical instillation, BCG binds to urothelial fibronectin and stimulates cytokine release, inflammatory cell recruitment, and Th1-mediated immune activation (7,8). Clinical studies have demonstrated that BCG significantly reduces tumor recurrence and progression compared with TURBT alone or intravesical chemotherapy (14,15). Maintenance BCG therapy further improves recurrence-free survival in high-risk patients. Despite its effectiveness, treatment-related adverse effects and BCG-unresponsive disease remain important clinical challenges (11,13). Conclusion: Intravesical BCG remains the cornerstone treatment for intermediate- and high-risk NMIBC. Its efficacy is primarily mediated through immune activation leading to durable antitumor responses and bladder preservation. Continued advances in immunotherapy and molecular oncology may improve future management strategies for patients with BCG-resistant disease.