Racial disparities in renal cell carcinoma: a single-payer healthcare experience

Abstract

Significant racial disparities in survival for renal cell carcinoma (RCC) exist between white and black patients. Differences in access to care and comorbidities are possible contributors. To investigate if racial disparities persist when controlling for access to care, we analyzed data from a single-payer healthcare system. As part of a case-control study within the Kaiser Permanente Northern California system, pathologic and clinical records were obtained for RCC cases (2152 white, 293 black) diagnosed from 1998 to 2008. Patient demographics, comorbidities, tumor characteristics, and treatment status were compared. Overall survival and disease-specific survival (DSS) were calculated by the Kaplan-Meier method. A Cox proportion hazards model estimated the independent associations of race, comorbidity, and clinicopathologic variables with DSS. We found that compared to white patients, black patients were diagnosed at a younger age (median 62 vs. 66 years, P < 0.001), were more likely to have papillary RCC (15% vs. 5.2%, P < 0.001), and had similar rates of surgical treatment (78.8% vs. 77.9%, P = 0.764). On multivariate analysis, advanced American Joint Committee on Cancer (AJCC) stage, lack of surgical treatment, larger tumor size, and higher grade were predictors of worse DSS. Race was not an independent predictor of survival. Therefore, we conclude that within a single healthcare system, differences in characteristics of black and white patients with RCC persist; black patients had different comorbidities, were younger, and had decreased tumor stage. However, unlike other series, race was not an independent predictor of DSS, suggesting that survival differences in large registries may result from barriers to healthcare access and/or comorbidity rather than disease biology.

Keywords: Health disparity; RCC; kidney cancer; outcome; survival.

Figure 1

(A) Overall survival (OS) and (B) disease‐specific survival (DSS) for black and white patients diagnosed with kidney cancer who received treatment within Northern California Kaiser Permanente between 1998 and 2008.

Figure 2

Disease‐specific survival (DSS) for black and white patients diagnosed with (A) Papillary and (B) Clear cell who received treatment within Northern California Kaiser Permanente between 1998 and 2008.