Long-term poverty, rurality, and geographic disparities in colorectal cancer: a spatial analysis in Texas

Abstract

Colorectal cancer (CRC) remains a leading cause of cancer morbidity and mortality in the United States and shows substantial geographic variation. Socioeconomically disadvantaged communities experience elevated CRC incidence, yet few studies have analyzed multi-decade poverty measures for long-term structural disadvantage. We analyzed CRC incidence from 2017 to 2021 across Texas using Texas Cancer Registry data. Age-sex-race/ethnicity standardized cases were incorporated as offsets in Bayesian spatial models to generate tract-level posterior mean relative risks. We evaluated four tract-level poverty measures (high poverty in 2021; persistent poverty since 1990; enduring poverty since 1980 and 1970), Rural–Urban Commuting Area (RUCA) classifications, and CRC screening rates among adults aged 50–75 years. Long-term poverty and rurality were independently associated with elevated CRC risk. Compared with urban tracts, micropolitan and rural tracts had 7–8% higher risks. Poverty measures defined over longer durations showed stronger associations with CRC incidence: high poverty in 2017–2021 (RR = 1.04, 95% CrI: 1.01–1.07), persistent poverty since 1990 (RR = 1.04, 1.00–1.08), enduring poverty since 1980 (RR = 1.06, 1.01–1.11), and enduring poverty since 1970 (RR = 1.09, 1.04–1.15). Higher tract-level CRC screening prevalence was inversely associated with CRC incidence (RR per 1% increase = 0.99). Long-term poverty and rural residence were associated with elevated CRC risk in Texas, even after adjusting for screening prevalence. Multi-decade poverty measures and updated RUCA classifications identified geographic disparities not captured by single-year poverty indicators and supported geographically targeted screening, prevention, and resource allocation efforts. These results can inform geographically targeted, efficiency-focused screening and prevention strategies, particularly in communities experiencing decades of structural disadvantage.