Factors predicting local or systemic side effects related to intravesical BCG (Bacillus Calmette-Guérin) therapy: a retrospective observational study

Objective Intravesical BCG treatment is the most frequently preferred adjuvant treatment option with its effective results in non-muscle invasive bladder tumors. Despite effective results, systemic and local side effects can be observed and can be one of the main reasons for treatment discontinuation. In this study we aimed to identify clinical factors predicting BCG-related side effects during intravesical BCG therapy in patients with non-muscle invasive bladder cancer. Methods Demographic and clinical data of patients who received intravesical adjuvant BCG therapy for non-muscle invasive bladder tumor were obtained from patient records. Data on side effects following intravesical BCG therapy and clinical approaches were collected. After creating the patient sample, binary logistic regression analysis was performed to identify parameters and independent risk factors predicting BCG-related side effects, and to evaluate data related to the clinical management of BCG-related side effects. Results Among the 276 patients included in the study, 23(8.3%) developed BCG-related local and systemic side effects. The mean IPSS(13.5 +/- 2.9 vs. 17.6 +/- 1.7) and mean tumor size(2.5 +/- 0.9 vs. 3.6 +/- 1.0 cm)were significantly higher in the group with BCG-related side effects(p < 0.001). The rate of CIS was significantly higher in the group with BCG-related side effects(21.7% vs. 3.9%,p = 0.004). Local side effects included cystitis symptoms in 18(78.2%) patients and epididymo-orchitis in 2(8.6%) patients. Systemic side effects included malaise and fever below 38.5 degrees C in 4(17.3%) patients, and fever above 38.5 degrees C lasting longer than 48 h in 2(8.6%) patients. Logistic regression analysis identified IPSS, tumor size, and the presence of CIS as independent risk factors. Conclusion High IPSS, large tumor size, and the presence of CIS were significant predictors of side effects during intravesical BCG therapy. Clinicians can ensure more effective use of BCG by preventing treatment discontinuation through approaches such as the use of quinolones and dose reduction in patients with these factors.