Introduction:

For individuals with muscle-invasive bladder cancer (MIBC), studies focused on racial disparities have shown black race is associated with 21% lower odds of guideline-based treatment (GBT) and differences in treatment explain 35% of observed black-white differences in survival. We aim to characterize how the interaction between race/ethnicity and receipt of GBT drive within- and between-race differences in survival for black, white, and Latino patients with MIBC.

Methods:

We identified patients diagnosed with cT2-4 MIBC from 2004-2013 in the National Cancer Database. GBT was defined by American Urological Association guidelines. A Cox proportional hazards model of patient mortality estimated effects of patient GBT status, race/ethnicity, and the GBT-by-race/ethnicity interaction, adjusting for covariates.

Results:

Of 60,566 MIBC patients with 125,821 person-years of post-treatment observation (max=11 years), 90.1% were white, 6.9% black, and 3.0% Latino. Half (50.2%) received GBT. Averaging across GBT status, Latino patients had lower hazard of death compared to black (HR 0.81, 95% CI 0.75-0.87) and white patients (HR 0.92, 0.86-0.98). Within racial/ethnic groups, GBT was associated with significantly lower hazard of death for black (HR 0.76, 0.70-0.82) and white (HR 0.78, 0.75-0.78), but not Latino patients (HR 0.90, 0.79-1.03).  Lastly, mortality risk of black patients with GBT was nearly equivalent to Latino individuals receiving non-GBT (HR=1.02, 0.92-1.14).    

Conclusion:

Our study illustrates how race-based treatment disparities influence survival outcomes and extend beyond black-white comparisons. Even though there are race-based treatment disparities, they are meager relative to the generally low utilization of GBT and  particular 'under-allocation' of GBT to vulnerable populations who arguably need it the most. Future efforts to improve the delivery of GBT, a factor directly impacted by urologic can providers, may mitigate the race-based survival differences observed in individuals with MIBC.

Funding: n/a