Weighting by Income Probabilities as a Novel Approach to Quantifying Differences in the Burden of Cancer by Income: A Case Study of Colorectal Cancer in Ohio.

[PURPOSE] Population-based cancer registries are a key data resource for catchment area informatics, but their utility for quantifying differences in cancer burden by socioeconomic status is limited. Here, we describe an approach that estimates cancer incidence along income gradients, leveraging a newly validated method called weighting by income probabilities (WIP).

[METHODS] We estimated income-specific colorectal cancer incidence, stratified by sex and race/ethnicity, in a catchment area (Ohio) as a case study. Income-specific numerator data (number of cancer cases per income bracket) were estimated using WIP, whereas denominators (population at risk by income bracket) were derived from US Census data.

[RESULTS] In the case study of the 52,257 patients with invasive colorectal cancer diagnosed in the catchment area of Ohio between 2010 and 2019, lower income was generally associated with higher incidence rates, except in non-Hispanic (NH) White female individuals. The highest incidence was observed in NH Black male individuals at 0-149% of the Federal Poverty Level, with 113.7 cases per 100,000 (95% CI, 99.6 to 129.3) in 2010-2012, compared with 57.8 (95% CI, 54.7 to 61.2) in their NH White counterparts. Sensitivity analyses showed that income-specific incidence statistics were robust to sources of error in numerator and denominator estimation, with incidence estimates varying by no more than 1.98% from the reference estimates.

[CONCLUSION] The approach described here accurately estimates cancer incidence along income gradients and can be expanded to estimate income-specific survival and mortality. The case study of colorectal cancer in Ohio demonstrates important insights into the burden of cancer by income. These granular income-specific data can enhance our understanding of the relationship between cancer burden and socioeconomic status and inform cancer surveillance, prevention, and control efforts.