Which social determinants of health have the greatest impact on rural–urban colorectal cancer mortality disparities?

New research reveals that certain social determinants of health—such as socioeconomic status, household characteristics, and racial/ethnic minority status—have significant effects on rural–urban disparities in colorectal cancer mortality rates. The findings are published in Cancer.

Using 1999–2020 colorectal cancer mortality data from the Centers for Disease Control and Prevention pertaining to all US counties, investigators assessed how different components of the Social Vulnerability Index might affect differences in colorectal cancer deaths in rural versus urban areas.

The Social Vulnerability Index includes 14 social determinants of health grouped into four related themes: socioeconomic status, household composition and disability, minority status and language, and housing and transportation.

Among 2,927 counties, rural counties had 11.8% higher colorectal cancer mortality than urban counties. Analyses revealed that 18.6% of that disparity was mediated by low socioeconomic status (higher poverty and unemployment and lower income and education), 8.8% by household characteristics, and 2.7% by racial/ethnic minority status.

Among all counties, poverty, unemployment, lacking a high school diploma, household crowding, and lacking a vehicle had the strongest impact on colorectal cancer mortality. While lacking access to a vehicle increased colorectal cancer mortality risk among all counties, rural counties were affected to a greater extent than urban counties.

“Our findings show that while socioeconomic vulnerability drives much of the disparity in colorectal cancer mortality, the rural–urban gap is shaped by a broader set of contextual factors,” said senior author Kelly M. Kenzik, MS, Ph.D., of the Patient-Reported Outcomes, Value, and Experience (PROVE) Center, Department of Surgery, Brigham and Women’s Hospital.

“Composite indexes like the Social Vulnerability Index offer important insight into population-level risk, but actionable progress will depend on domain-specific measures that identify concrete barriers and facilitators, guiding resource allocation and policy tailored to local needs.”