Regional Variation in Bladder Cancer Clinical Trial Availability in the US.

Importance: Geographic disparities in cancer clinical trial access are well described in the US, but patterns in bladder cancer remain poorly defined. Objective: To evaluate bladder cancer trial availability across US counties and its associations with epidemiologic and socioeconomic factors. Design, Setting, and Participants: This cross-sectional study of completed, open, or active bladder cancer clinical trials from June 1, 2019, to June 1, 2025, on ClinicalTrials.gov used data on county-level incidence, mortality, and Social Vulnerability Index (SVI) obtained from the Centers for Disease Control and Prevention, the National Cancer Institute, and the Agency for Toxic Substances and Disease Registry and included interventional bladder cancer clinical trials of adults at 1 or more US sites. Data were analyzed from July 1, 2025, to October 20, 2025. Exposures: Epidemiologic and socioeconomic characteristics of bladder cancer clinical trials. Main Outcome and Measures: Trial availability was defined as 1 or more bladder cancer trial sites per county. Trial volume (number of unique trials per county) was modeled using a multivariable zero-inflated negative binomial regression and reported as incidence rate ratios. Associations between trial characteristics and location in highest vs lowest bladder cancer mortality quintile counties were assessed using a generalized linear mixed-effects logistic regression model. Results: The study identified 436 bladder cancer trials across 713 US counties. Of 3145 counties, 713 (22.7%) had 1 or more trial sites, and 2432 (77.3%) had none. Most trials were sponsored by pharmaceutical companies (211 [48.4%]) or academic institutions (170 [39%]). Most trials were drug focused (350 [80.2%]) and early phase (phase 1 or phase 2; 314 [72%]). Higher bladder cancer incidence was associated with higher trial rates (incidence rate ratio [IRR], 1.03; 95% CI, 1.003-1.06). A higher bladder cancer mortality rate was associated with lower trial rates (IRR, 0.80; 95% CI, 0.73-0.88). Compared with counties with a high SVI, trial rates were higher in counties with a lower-middle (IRR, 1.57; 95% CI, 1.18-2.08), middle-high (IRR, 1.60; 95% CI, 1.22-2.11), and low SVI (IRR, 2.53; 95% CI, 1.89-3.38). Of 7091 trial sites, 225 (3.2%) were located in counties in the highest quintile for bladder cancer mortality. Pharmaceutical company-sponsored trials were less likely than academic trials to be in counties with the highest mortality rate (odds ratio, 0.11; 95% CI, 0.04-0.29; P < .001), as were trials enrolling fewer than 100 participants compared with more than 100 participants (odds ratio, 0.20; 95% CI, 0.09-0.46; P < .001). Conclusions and Relevance: In this cross-sectional study of 436 bladder cancer clinical trials across US counties, most counties lacked trials, with geographic availability concentrated in counties with a high bladder cancer incidence and low social vulnerability. Expanding trial sites to counties with a high mortality rate or a high SVI may improve the geographic availability of bladder cancer clinical trials.