Understanding the Effect of Socioeconomic Gradient within Racial/Ethnic Groups on Breast, Colorectal and Prostate Cancer Outcomes

The association between race/ethnicity and socioeconomic status is complex and varies across and within racial and ethnic groups with regards to cancer outcomes. This study evaluates the combined effects of race/ethnicity and poverty level on mortality after accounting for demographic, tumor, treatment and comorbidity characteristics. We used the SEER-Medicare database for patients diagnosed with breast, colorectal or prostate cancers in 1992-2000 with five year follow-up. The unadjusted analysis of racial and ethnic groups found that both African Americans and Latinos compared to Whites experienced excess mortality.;The unadjusted analysis of poverty levels identified that all poverty levels compared to areas with the lowest levels of poverty were at increased risk for cancer-specific and all-cause mortality. After adjusting for patient demographic characteristics, co-morbidities, tumor characteristics and treatment, and poverty level, African Americans remained at increased risk for breast (HR 1.18, 95% CI 1.06-1.31), colorectal (HR 1.19, 95% CI 1.10-1.29) and prostate (HR 1.19, 95% CI 1.09-1.30) cancer specific mortality and colorectal all-cause mortality (HR 1.10, 95% CI 1.04-1.16). Asians consistently exhibited fully adjusted decreased risk for all mortality outcomes whereas Latinos varied between decreased risk, increased risk and no difference from Whites depending on cancer. An interaction between race/ethnicity and poverty was found in breast all-cause mortality (p=0.021). Where an interaction was demonstrated, the association between increasing poverty level and increasing mortality risk among African Americans did not remain significant. In addition, Latinos' positive association between poverty and mortality was only found for prostate cancer-specific mortality. However, Whites and Asians consistently showed a positive association with mortality as poverty levels increased across cancers and outcomes.;A positive association between poverty and cancer-specific and all-cause mortality for breast, prostate and colorectal cancers was found among specific racial/ethnic groups. An interaction effect between poverty and race/ethnicity was identified in breast all-cause mortality. For particular racial/ethnic groups such as African Americans and Latinos, decreased poverty does not lessen mortality risk.