Understanding Treatment Completion and Tolerability of Intravesical Bacillus Calmette-Guérin (BCG) for Non-muscle Invasive Bladder Cancer in a Single UK Health Board

Background Intravesical Bacillus Calmette-Guérin (BCG) is the standard immunotherapy for high-risk non-muscle invasive bladder cancer (NMIBC). A considerable proportion of patients do not respond adequately to this treatment. This study aims to analyze the rates of and reasons for discontinuation of BCG therapy within a single UK health board. Methods A retrospective study of 40 patients who underwent BCG treatment for NMIBC at Glangwili General Hospital (Hywel Dda University Health Board) from July 2021 to July 2025. Data on patient demographics, tumor characteristics, treatment adherence, and adverse events were collected from medical records. Results Of the 40 patients, 60.0% (n=24) did not complete the full BCG course. Only seven patients (17.5%) exhibited BCG intolerance, grade 2+ toxicities, or related admissions. Smoking status was poorly documented, available for only 10 patients (25.0%). Among these, 15% (n=6) were ex-smokers, 5% (n=2) were current smokers, and 5% (n=2) had never smoked. Adherence to dosing intervals was generally good; 16 of 24 non-completers (66.7%) and 10 of 14 completers (71.4%) received their doses on time (≤14 days). Tumor characteristics showed a high prevalence of high-grade tumors in both non-completers (13/16, 81.3%) and completers (8/10, 80.0%). Conclusion Within our Health Board, BCG failure is multifactorial. It is important to improve data collection, particularly on smoking status and reasons for discontinuation. This will provide us with a more comprehensive understanding of BCG failure and help us improve treatment protocols. A multidisciplinary approach is needed to optimize BCG adherence and effectively manage high-risk NMIBC.