Abstract 737: Diet quality and risk of gastric adenocarcinoma: The Multiethnic Cohort

Abstract Background: Certain diet components (i.e. low intake of fruit/vegetables and high intake of salt and processed meats) have been associated with risk of gastric cancer. However, it is unclear whether overall diet quality assessed by pre-defined indices, that take into account the complexity of dietary intake, is associated with gastric cardia and distal adenocarcinoma particularly in a racially and ethnically diverse population. Our objectives are to 1) examine the association of a variety of diet quality indices with risk of gastric cardia and distal adenocarcinoma and 2) assess if there are any subgroups that may benefit from better diets to reduce risk of gastric adenocarcinoma. Methods: The analysis included 176,752 men and women aged 45-75 from the Multiethnic Cohort (MEC), who were African American, Japanese American, Latino, Native Hawaiian, or White, and completed a quantitative food frequency questionnaire (QFFQ) at cohort entry. Incident cases of gastric cancer (cardia ICD-O-3 C16.0 and non-cardia adenocarcinoma C16.1-C16.6) were identified by linkages with the Surveillance, Epidemiology, and End Results (SEER) cancer registries. Dietary indices, Alternative Healthy Index-2010 (AHEI-2010), Healthy Eating Index-2015 (HEI-2015), Dietary Approach to Stop Hypertension (DASH) score, alternate Mediterranean Diet (aMED) score, and Dietary Inflammatory Index (DII®), were calculated from the QFFQ and categorized into quintiles. Multivariable Cox models were used to estimate the association between dietary indices and gastric cancer risk by anatomic site. Effect modification was assessed for distal cancer by sex, smoking status, and aspirin use. Results: A total of 207 incident cases of gastric cardia and 836 incident cases of gastric non-cardia were identified during an average follow up of 19.2 years. We did not observe any significant associations between any of the dietary indices and gastric cancer for both cardia and non-cardia tumors. However, we observed effect modification by aspirin use for aMED (P for heterogeneity = 0.01) as well as for DII (P for heterogeneity = 0.02). Among ever aspirin users, we observed an inverse association between aMED (HRQ5 vs Q1: 0.82, 95% CI: 0.53-1.26, Ptrend = 0.03) with non-cardia cancer, and the association with DII® was borderline statistically significant for the trend test (HRQ5 vs Q1: 0.86, 95% CI: 0.57-1.29, Ptrend = 0.07). Conclusion: In a multiethnic population, we did not observe overall significant associations between these dietary quality indices and risk of gastric cancer. However, among ever aspirin users there could be a reduction of gastric non-cardia adenocarcinoma risk with a higher adherence to a Mediterranean diet. Citation Format: Nicholas Acuna, Song-Yi Park, Anna H. Wu, Lynne R. Wilkens, V. Wendy Setiawan. Diet quality and risk of gastric adenocarcinoma: The Multiethnic Cohort [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 737.