Local Toxicity Patterns Associated with lntravesical bacillus Calmette‐Guérin: A Southwest Oncology Group Study

Background: While the efficacy of bacillus Calmette-Cuerin (BCG) immunotherapy has been demonstrated, the relative benefit, given a seemingly high incidence and severity of toxicities, remains an issue. Adequate understanding and management of toxicities can maximize the safety of the treatment and enable the administration of required doses of BCC intravesical therapy. Methods: All week-to-week symptoms recorded for the 143 immunotherapy-naive participants assigned to the BCG arm of SWOG-8216, BCG vs. Doxorubicin in Superficial Bladder Cancer were analyzed in order to document the pattern of toxicities in the first six week induction course of intravesical BCC treatments. The statistical analysis consisted of fitting logistic regression models to these data for the probability of irritative bladder symptoms (16s). Results: In the optimal model, the probability of IBS depends only on whether there was IBS associated with the previous treatment, and not on which treatment. The estimated probability of having IBS when there were no 16s associated with the previous instillation is 0.136, whereas the estimated probability of having IBS when there was IBS associated with the previous instillation is 0.689. Conclusions: Irritative bladder symptoms are unlikely in the week after the first intravesical BCG treatment. Once a patient experiences IBS, he or she is more likely to have IBS with the next and subsequent treatments. Clinicians can use the findings of this analysis when informing their patients about the treatment course and when making decisions about continuing treatments.