Background: Gastric cancer is the fifth most common cancer worldwide, with a disproportionate burden among populations living in poverty. Dietary patterns have been linked to gastric cancer risk and are often influenced by socioeconomic position. However, it is unclear whether the food environment in which people live, including proximity to healthy foods and socioeconomic factors that impede access to healthy foods, may contribute to socioeconomic disparities in gastric cancer incidence. Purpose: To examine associations between county level Food Environment Index (FEI) and gastric cancer incidence rates and assess whether associations vary by socioeconomic status and rurality. We also evaluated whether adding a measure of fast food outlets per capita to the FEI strengthens associations. Methods: Analyses for this ecologic study are based on 3,120 out of a total of 3,143 U.S. counties, for which FEI information was available and estimated age-adjusted gastric cancer incidence rates from 2016-2020. The FEI was defined based on indicators of socioeconomic status, unhealthy and healthy dietary options using county-level data from the U.S. Department of Agriculture (2011-2015). The FEI score was categorized into tertiles for analysis, with higher scores representing better quality. In secondary analysis, we evaluated the FEI incorporating an additional measure of the number of fast food restaurants per capita. Multivariable multinomial logistic regression models were used to estimate odds ratios for associations of our exposure of county-level FEI and our outcome of county-level gastric cancer incidence rates, stratified by county rurality and socioeconomic status (SES). Results: The FEI was inversely associated with gastric cancer incidence after accounting for gastric cancer risk factors (OR (95% CI) for high vs. low FEI = 0.43 (0.3, 0.7) at high vs. low incidence). Findings were similar in models assessing the FEI incorporating fast food per capita (OR (95% CI) for high vs. low FEI2 = 0.43 (0.3, 0.7) at high vs. low incidence. We did not observe any significant variation in associations across rurality (pint=0.97) but we did observe slight variation by socioeconomic status (pint<0.05). Discussion: Higher quality food environment, both with and without incorporating fast food outlets per capita, were associated with lower gastric cancer incidence rates in this ecological study. Further research is warranted to elucidate the role of FEI components on gastric cancer risk, and to develop targeted policy recommendations to reduce cancer risk through improved healthy food access.
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