Geographic access to colonoscopy, neighborhood social vulnerability, and associations with late-stage colorectal cancers in Maryland: 2010-2021.

Background: Early detection of colorectal cancer (CRC) significantly improves survival. However, geographic inaccessibility of colonoscopies may prevent timely and effective screenings. The relationship between spatial access to colonoscopy providers, social determinants of health, and stage at CRC diagnosis remains understudied. We evaluated how place-based factors and individual characteristics are related to CRC diagnosis stage.

Methods: This cross-sectional, population-based study includes all CRC patients aged 50-84 at diagnosis between 2010 and 2021 from the Maryland Department of Health's Cancer Registry (n = 21,599). We measured the spatial (geographic) accessibility to colonoscopy providers across Maryland at the census tract level using the Enhanced Two-Step Floating Catchment Area (E2SFCA) method. Multilevel logistic regression models were used to examine associations between late-stage CRC diagnosis and spatial accessibility, four census tract-level social vulnerability themes, rurality, and individual-level covariates.

Results: Among colorectal cancer cases with known stage (n = 19,239), 63.2 % (n = 12,151) were diagnosed at late-stage. Increasing socioeconomic vulnerability quartiles were associated with greater odds of late-stage diagnosis (Q4 vs Q1: OR, 1.17; 95 % CI, 1.04-1.32), while rural residence was associated with lower odds (OR, 0.69; 95 % CI, 0.59-0.80). Geographic access to colonoscopy providers was not significantly associated with late-stage diagnosis.

Conclusion: Findings suggest that non-spatial accessibility factors and place-based social determinants of health are more important than geographic access alone in influencing risk of late-stage colorectal cancer diagnosis. Public health interventions in Maryland should aim to target communities of high social vulnerability, particularly those with low socioeconomic status. Although our analysis is limited to Maryland, the results are broadly consistent with similar studies across U.S. settings and may be relevant in other states. Future studies should examine the barriers to CRC screening and diagnosis beyond geographic access.