Diet quality and risk of gastric adenocarcinoma: The Multiethnic Cohort

Background: Certain dietary patterns (i.e., low intake of fruit/vegetables and high intake of salt and processed meats) have been associated with the risk of gastric cancer. However, it is unclear whether overall diet quality assessed by predefined indices that consider the complexity of dietary intake is associated with gastric cardia and distal adenocarcinoma. Objectives: To examine the association of a variety of diet indices with the risk of gastric cardia and distal adenocarcinoma and assess whether there are any subgroups that may benefit from better diets to reduce the risk of gastric adenocarcinoma. Methods: Dietary indices of interest included the Alternative Healthy Index (AHEI)-2010, Healthy Eating Index (HEI)-2015, the Dietary Approach to Stop Hypertension, alternate Mediterranean diet (aMED), and the energy-adjusted Dietary Inflammatory Index. Results: After an average follow-up time of 19.2 years, there were 836 incident cases of gastric distal adenocarcinoma and 207 cases of gastric cardia adenocarcinoma. We did not observe any significant associations between the dietary indices and gastric cancer for either anatomic site. Among former aspirin users, we observed an inverse association between aMED with distal cancer (HRQ5 vs. (Q1): 0.64; 95% CI: 0.33, 1.23; P-trend = 0.03). Never smokers, who showed high-quality diet according to AHEI-2010, exhibited a 40% decreased risk of gastric distal cancer compared with those with the poorest-quality AHEI-2010 diet (HRQ5 vs. Q1: 0.60; 95% CI: 0.41, 0.88; P-trend = 0.08). Conclusions: In a multiethnic population, we did not observe overall significant associations between these dietary quality indices and risk of gastric cancer. However, among former aspirin users and never smokers, there could be a reduction of gastric distal adenocarcinoma risk with a higher adherence to a Mediterranean diet.