Abstract 2239: Comparative effectiveness of cystoscopy surveillance strategies on mortality in non-muscle invasive bladder cancer: A target trial emulation using real-world data
Authors: McGee Emma E. , de Albéniz Xabier García , Eliassen A. Heather , Yim Kendrick , Dickerman Barbra A. , Preston Mark A. , Hernán Miguel 
Published: March 2024

Abstract
Background: More than 60,000 U.S. adults are diagnosed with non-muscle invasive bladder cancer (NMIBC) each year. These patients are recommended to undergo surveillance via repeated cystoscopies. However, the ideal frequency of post-diagnostic cystoscopy surveillance remains unknown, and efforts are underway to de-escalate surveillance given uncertainty regarding its effect on mortality. We therefore aimed to compare the effectiveness of different post-diagnostic cystoscopy surveillance strategies on bladder cancer specific mortality.
Methods: We used observational data from the Surveillance, Epidemiology, and End Results (SEER)-Medicare linkage to emulate a target trial, i.e., a hypothetical, pragmatic randomized trial that would answer our causal question. Eligible individuals were aged 66 years or older, diagnosed with NMIBC (Ta, Tis, or T1) classified as urothelial carcinoma between January 1, 2000 and December 31, 2017, and had completed their first post-diagnostic cystoscopy. We compared 10-year risks of bladder cancer specific mortality under cystoscopy surveillance every 3, 6, and 12 months separately among individuals at low, intermediate, and high risk. We estimated mortality risks using inverse probability weighted pooled logistic regression.
Results: Among 58,004 eligible individuals, the median age at diagnosis was 77 years (interquartile range: 72, 82) and 75.6% were male. Over the 10 year follow-up period, 4,977 bladder cancer deaths occurred. Among individuals at high risk, the estimated 10-year bladder cancer mortality risks were 24.5% under the 3 month strategy, 26.6% under the 6 month strategy, and 27.3% under the 12 month strategy. Compared with cystoscopy every 3 months, the risk differences were 2.1% (95% confidence interval [CI]: -0.3, 3.8) for cystoscopy every 6 months, and 2.8% (95% CI: 1.0, 4.4) for cystoscopy every 12 months. For patients in the intermediate risk group, 10-year bladder cancer mortality risks were 14.4% under the 3 month strategy, 15.1% under the 6 month strategy, and 15.9% under the 12 month strategy. The risk differences were 0.7% (95% CI: -0.6, 2.0) for 6 vs. 3 months and 1.6% (95% CI: 0.3, 2.7) for 12 vs. 3 months. Among individuals at low risk, these mortality risks were 8.3% under the 3 month strategy, 9.2% under the 6 month strategy, and 9.6% under the 12 month strategy. Risk differences were 1.1% (95% CI: -0.1, 2.5) for 6 vs. 3 months and 1.5% (95% CI: 0.2, 3.0) for 12 vs. 3 months.
Conclusions: We estimated that more frequent cystoscopy may result in clinically meaningful reductions in bladder cancer mortality among high risk patients. Among low and intermediate risk patients, more frequent cystoscopy may result in modest absolute risk reductions. Decision-makers should also consider the clinical and financial burden and risk of complications associated with more frequent surveillance.
Citation Format: Emma E. McGee, Xabier García de Albéniz, A. Heather Eliassen, Kendrick Yim, Barbra A. Dickerman, Mark A. Preston, Miguel Hernán. Comparative effectiveness of cystoscopy surveillance strategies on mortality in non-muscle invasive bladder cancer: A target trial emulation using real-world data [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2239.