Racial disparities in receipt and comparative effectiveness of oxaliplatin for stage III colon cancer in older adults

Abstract

Background: African Americans in the United States have higher rates of colon cancer mortality than other races. This study examines the use of oxaliplatin, a novel chemotherapeutic agent approved in 2004, among African American and Caucasian American patients with stage III colon cancer to determine whether differential receipt or differential effectiveness of the drug may explain the racial disparity in colon cancer mortality.

Methods: The authors conducted a population-based retrospective cohort study of stage III colon cancer patients aged 65 years and older treated from 2004 through 2006 who initiated chemotherapy within 90 days of surgical resection (N = 1162) using Surveillance, Epidemiology and End Results-Medicare data. Patients receiving oxaliplatin (n = 477) were compared with those receiving 5-fluorouracil without oxaliplatin (n = 685). The authors estimated prevalence ratios and hazard ratios (HRs) using multivariate binomial regression and Cox models to evaluate racial differences in oxaliplatin receipt and survival.

Results: African Americans were as likely as Caucasian Americans to receive oxaliplatin (40.5 vs 41.1%; prevalence ratio, 0.90; 95% confidence interval [CI], 0.71-1.13). Oxaliplatin was associated with lower mortality compared with 5-fluorouracil (HR, 0.76; 95% CI, 0.58-1.00). This benefit appeared stronger among African Americans (HR, 0.31; 95% CI, 0.09-1.05) than Caucasian Americans (HR, 0.80; 95% CI, 0.60-1.06).

Conclusions: In Medicare-insured patients receiving chemotherapy, the authors observed no meaningful racial disparities in receipt of oxaliplatin and, among those receiving it, potentially better survival among African Americans. Differential receipt and effectiveness of oxaliplatin-containing regimens does not appear to contribute to the previously documented racial disparities in colon cancer survival. Understanding reasons for potentially enhanced effectiveness among African Americans may inform efforts to resolve racial disparities in colon cancer outcomes.