Intrastate variations in rural cancer risk and incidence: An Illinois case study

Abstract

Context: Although rural-urban cancer disparities have been explored with some depth, disparities within seemingly homogeneous rural areas have received limited attention. However, exploration of intrarural cancer incidence may have important public health implications for risk assessment, cancer control, and resource allocation. Objective: The objective of this study was to explore intrastate rural cancer risk and incidence differences within Illinois. Design: Illinois's 83 rural counties were categorized into northern, central, and southern regions (IL-N, IL-C, and IL-S, respectively). Chi-square test for independence and analysis of variance calculations were performed to assess regional differences in demographic characteristics, socioeconomic deprivation, smoking history, obesity, cancer-screening adherence, and density of general practitioners. Age-adjusted incidence rates were calculated for 5 cancer categories: all cancers combined, lung, colorectal, breast (female), and prostate cancers. Unadjusted and adjusted incidence rate ratios (IRRs) were calculated to evaluate regional differences in rates for each cancer category. Results: Socioeconomic deprivation varied by region: 4.5%, 6.9%, and 40.6%of IL-N, IL-C, and IL-S counties, respectively (P