Race modifies survival benefit of guideline-based treatment: Implications for reducing disparities in muscle invasive bladder cancer.

Samuel L Washington,Maxwell V Meng,Steven E Gregorich,Sima P Porten,Anne M Suskind

doi:10.1002/cam4.3429

Abstract

BackgroundBlack individuals with muscle‐invasive bladder cancer (MIBC) experienced 21% lower odds of guideline‐based treatment (GBT) and differences in treatment explain 35% of observed Black‐White differences in survival. Yet little is known of how interactions between race/ethnicity and receipt of GBT drive within‐ and between‐race survival differences.MethodsBlack, White, and Latino individuals diagnosed with nonmetastatic, locally advanced MIBC from 2004 to 2013 within the National Cancer Database were included. Guideline‐based treatment was defined as the receipt including one or more of the following treatment modalities: radical cystectomy (RC), neoadjuvant chemotherapy with RC, RC with adjuvant chemotherapy, and/or chemoradiation based on American Urological Association guidelines. Cox proportional hazards model of mortality estimated effects of GBT status, race/ethnicity, and the GBT‐by‐race/ethnicity interaction, adjusting for covariates.ResultsOf the 54 910 MIBC individuals with 125 821 person‐years of posttreatment observation (max = 11 years), 6.9% were Black, and 3.0% were Latino. Overall, 51.4%, 45.3%, and 48.5% of White, Black, and Latino individuals received GBT. Latino individuals had lower hazard of death compared to Black (HR 0.81, 95% CI 0.75‐0.87) and White individuals (HR 0.92, 95% 0.86‐0.98). With GBT, Latino and White individuals had similar outcomes (HR = 1.00, 95% 0.91‐1.10) and both fared better than Black individuals (HR = 0.88, 95% 0.79‐0.99 and HR = 0.88, 95% 0.83‐0.94, respectively). Without GBT, Latino individuals fared better than White (HR = 0.85, 95% 0.77‐0.93) and Black individuals (HR = 0.74, 95% 0.67‐0.82) while White individuals fared better than Black individuals (HR = 0.87, 95% 0.83‐0.92). Black individuals with GBT fared worse than Latinos without GBT (HR = 1.02, 95% 0.92‐1.14), although not statistically significant.ConclusionLow GBT levels demonstrated an “under‐allocation” of GBT to those who needed it most—Black individuals. Interventions to improve GBT allocation may mitigate race‐based survival differences observed in MIBC.

Highlights

Racial disparities in bladder cancer in the United States represent the end-result of a series of “leaks in the pipeline” from diagnosis to treatment
Interventions to improve guideline-based treatment (GBT) allocation may mitigate race-based survival differences observed in muscle-invasive bladder cancer (MIBC)
In 2020 alone, an estimated 62 100 incident cases and 13 050 cancer-specific deaths will be attributed to bladder cancer, with Black individuals presenting with higher stage disease and worse 5-year survival rates despite lower overall incident rates compared to White individuals.[1,2]

Summary

Introduction

Racial disparities in bladder cancer in the United States represent the end-result of a series of “leaks in the pipeline” from diagnosis to treatment. Prior studies have explored racial disparities with respect to survival, often limited to Black-White comparisons, and generalized the effect to entire racial groups using an unitary approach which focuses on differences by one category alone (ie, race), or a multiplicative approach which layers additional factors, such as SES, on the primary category.[5] Recent studies have shown Black individuals with muscle-invasive bladder cancer (MIBC) have 21% lower odds of guideline-based treatment (GBT) and, in turn, GBT explained 35% of observed Black-White differences in survival, with an insignificant contribution from inherent tumor characteristics.[3,4] the effects of race and receipt of GBT may interact, resulting in nonadditive (multiplicative) effects.

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