Racial Disparities in Late Survival after Rectal Cancer Surgery

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Abstract
African-American patients experience higher mortality than Caucasian patients after surgery for most common cancer types. Whether longterm survival after rectal cancer surgery varies by race is less clear. Using 1992 to 2003 Surveillance, Epidemiology, and End Results (SEER)-Medicare data, we examined race and longterm survival among African-American and Caucasian rectal cancer patients undergoing resection. We identified racial differences in patient characteristics, structure, and processes of care. We then assessed mortality using a Cox proportional hazards model, sequentially adding variables to explore the extent to which they attenuated the association between race and mortality. African-American patients had a substantially poorer overall survival rate than Caucasian patients did. Five-year survival rates were 41% and 50%, respectively (p < 0.0001). African Americans were younger (p=0.006), more likely to reside in low income areas (p < 0.0001), and had more baseline comorbid disease (p < 0.0001). They were also more likely to be diagnosed emergently (p < 0.001) and with more advanced cancer (p < 0.001). Accounting for demographic and clinical characteristics reduced the mortality difference, although it remained pronounced (hazard ratio=1.13, CI=1.01 to 1.26). African Americans were more likely to be treated by low volume surgeons and less likely to receive adjuvant therapy (48.6% versus 60.9%, p < 0.0001). After adjusting for provider variables, the hazard ratio for mortality by race was additionally attenuated and became statistically nonsignificant (hazard ratio=1.05, CI=0.92 to 1.20). Poorer longterm survival after rectal cancer surgery among African Americans is explained by measurable differences in processes of care and patient characteristics. These data suggest that outcomes disparities could be reduced by strategies targeting earlier diagnosis and increasing adjuvant therapy use among African-American patients.