Racial-Ethnic Comparisons in Surgical Treatment and Outcomes of Non-Metastatic Renal Cell Cancer in an Equal Access Health System

Background: Access to care has been implicated in racial-ethnic disparities in surgical treatment and survival for patients with renal cell carcinoma (RCC) in the United States. We assessed whether there were racial-ethnic disparities in surgery receipt and clinical outcomes of RCC in the equal access U.S. Military Health System (MHS). Materials and Methods: We used the MilCanEpi database to study a cohort of patients aged 18 and older who were diagnosed with stage I-III RCC between 1998 and 2014. Treatment with nephrectomy was evaluated in Poisson regression models expressed as adjusted incidence rate ratios (AIRRs) with 95% confidence intervals (CIs). Risk of recurrence and all-cause death were estimated using multivariable Cox regression models. Results: The study included 1371 non-Hispanic White, 362 non-Hispanic Black, and 177 Hispanic patients. Black patients had lower rates of nephrectomy compared to non-Hispanic White patients overall (AIRR = 0.83, 95% CI = 0.72, 0.95) and in strata for stage I (AIRR = 0.74, 95% CI = 0.64, 0.87) or clear cell subtype (AIRR = 0.57, 95% CI = 0.42, 0.77). Hispanic patients had similar overall rates of nephrectomy as non-Hispanic White patients (AIRR = 1.16, 95% CI = 0.98, 1.37) and higher rates among those with clear cell RCC (AIRR = 1.40, 95% CI = 1.01, 1.96). Black patients had lower risk of recurrence (AHR = 0.61, 95% CI = 0.41, 0.92) relative to non-Hispanic White patients with no other racial-ethnic differences in outcomes in multivariable models. Conclusion: In the equal access MHS, there were some significant variations in rates of nephrectomy between racial-ethnic groups overall and among patient subgroups by tumor stage and histology. Despite observed lower surgery rates among non-Hispanic Black patients, the risk of recurrence or survival was lower or equal as compared to non-Hispanic White patients with non-metastatic RCC. Further research on factors other than access to care that may explain the differences in treatment and outcomes among racial-ethnic groups is needed.