Effect of intravesical chemotherapy on the survival of patients with non-muscle-invasive bladder cancer undergoing transurethral resection: a retrospective cohort study among older adults

Background: The average age of diagnosis for bladder cancer is 73 and about 75 percent of all bladder cancers are non-muscle invasive at initial diagnosis. It is recommended that non-muscle invasive bladder cancers (NMIBC) should be treated with transurethral resection of the bladder tumor (TURBT) followed by chemotherapy. However, there is no large-scale study from real-world databases to show the effectiveness of chemotherapy on the survival of older adults with NMIBC that have undergone TURBT. This study aimed to investigate the effects of chemotherapy on survival among older NMIBC patients with TURBT. Methods: Using the Surveillance, Epidemiology, and End Results (SEER) database (2010-2015), we performed analyses of cancer-specific mortality and overall mortality comparing chemotherapy versus no chemotherapy after TURBT. Coarsened exact matching was performed to balance the baseline patient characteristics. Cox proportional hazards and Kaplan-Meir analyses were used to evaluate survival outcomes. Results: A total of 3,222 matched patients with 1,611 in each arm (chemotherapy and no chemotherapy) were included in our study. After adjusting for covariates, multivariable Cox regression analyses show chemotherapy was associated with lower cancer-specific mortality (HR 0.63; 95% CI 0.42-0.94; p value 0.024). However, chemotherapy did not have any effect on overall mortality (HR 0.84; 95% CI 0.65-1.07; p value 0.159). The Kaplan-Meier curves show the protective effects of chemotherapy on cancer specific survival (p=0.032), but not on overall survival (p=0.34). Conclusion: Chemotherapy improved cancer specific survival among older patients with non-muscle invasive bladder cancer undergoing TURBT surgery, but it had no effect on overall survival. There is a need for more granular level real-world data on chemotherapy regimens and dosage to effectively investigate the effects of chemotherapy on survival of older patients with NMIBC that have undergone TURBT.