Racial disparities and socioeconomic status in association with survival in a large population-based cohort of elderly patients with colon cancer

Background. To the authors' knowledge, few studies have addressed racial disparities in the survival of patients with colon cancer by adequately incorporating treatment and socioeconomic factors in addition to patient and tumor characteristics. Methods. The authors studied a nationwide and population-based, retrospective cohort of 18,492 men and women who were diagnosed with stage 11 or III colon cancer at age >= 65 years between 1992 and 1999. This cohort was identified from the Surveillance, Epidemiology, and End Results (SEER) cancer registries-Medicare linked databases and included up to 11 years of follow-up. Results. A larger proportion (70%) of African -American patients with colon cancer fell into the poorest quartiles of socioeconomic status compared with Caucasians (21%). Patients who lived in communities with the lowest socioeconomic level had 19% higher all-cause mortality compared with patients who lived in communities with the highest socioeconomic status (hazards ratio [HR], 1.19; 95% confidence interval [95% CI], 1.13-1.26; P <.001 for trend). The risk of dying was reduced only slightly after controlling for race/ethnicity (HR, 1.17; 95% CI, 1.10-1.24). Compared with Caucasian patients with colon cancer, African-American patients were 21% more likely to die after controlling for age, sex, comorbidity scores, tumor stage, and grade (HR, 1.21; 95% CI, 1.12-1.30). After also adjusting for definitive therapy and socioeconomic status, the HR of mortality was only marginally significantly higher in African Americans compared with Caucasians for all-cause mortality (HR, 1.10; 95% CI, 1.02-1.19) and colon cancer-specific mortality (HR, 1.16; 95% CI, 1.01-1.33). Conclusions. Lower socioeconomic status and lack of definitive treatment were associated strongly with decreased survival in both men and women with colon cancer. Racial disparities in survival were explained substantially by differences in socioeconomic status.