Socioeconomic disparities in colorectal cancer mortality in the United States, 1990-2007.

United States colorectal cancer mortality rates have declined; however, disparities by socioeconomic status and race/ethnicity persist. The objective of this study was to describe the temporal association between colorectal cancer mortality and socioeconomic status by sex and race/ethnicity. Cancer mortality rates in the United States from 1990 to 2007, which were generated by the National Center for Health Statistics, and county-level socioeconomic status, which was estimated as the proportion of county residents living below the national poverty line based on 1990 US Census Bureau data, were obtained from the Surveillance, Epidemiology, and End Results program. The Kunst-Mackenbach relative index of inequality, which considers data across all poverty levels when comparing risks in the poorest (≥ 20%) and richest counties (<10%), was calculated as the measure of association. The study found that colorectal cancer mortality rates were significantly lower in the poorest counties than the richest counties during 1990-1992 among non-Hispanic whites, non-Hispanic black women and non-Hispanic API men. Over time though the tendency was for the poorest counties to have higher mortality rates. By 2003-2007 colorectal cancer mortality rates were significantly higher in the poorest than the richest counties among all sex-race/ethnicity groups. This disparity was most noticeable and appeared to be increasing most among Hispanic men. This suggests that socioeconomic disparities in colorectal cancer mortality were apparent after stratifying by sex and race/ethnicity and reversed over time. Further studies into the causes of these disparities would provide a basis for targeted cancer control interventions and allocation of public health resources.