Abstract and Introduction
Few prospective studies have examined associations between diet quality and pancreatic ductal adenocarcinoma (PDAC), or comprehensively compared diet quality indices. We conducted a prospective analysis of adherence to the Healthy Eating Index (HEI)-2015, alternative HEI-2010, alternate Mediterranean diet (aMed), and 2 versions of Dietary Approaches to Stop Hypertension (DASH; Fung and Mellen) and PDAC within the National Institutes of Health (NIH)-AARP Diet and Health Study (United States, 1995–2011). The dietary quality indices were calculated using responses from a 124-item food frequency questionnaire completed by 535,824 participants (315,780 men and 220,044 women). We used Cox proportional hazards regression models to calculate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for each diet quality index and PDAC. During follow-up through 2011 (15.5-year median), 3,137 incident PDAC cases were identified. Compared with those with the lowest adherence quintile, participants with the highest adherence to the HEI-2015 (HR = 0.84, 95% CI: 0.75, 0.94), aMed (HR = 0.82, 95% CI: 0.73, 0.93), DASH-Fung (HR = 0.85, 95% CI: 0.77, 0.95), and DASH-Mellen (HR = 0.86, 95% CI: 0.77, 0.96) had a statistically significant, lower PDAC risk; this was not found for the alternative HEI-2010 (HR = 0.93, 95% CI: 0.83, 1.04). This prospective observational study supports the hypothesis that greater adherence to the HEI-2015, aMed, and DASH dietary recommendations may reduce PDAC.
Although pancreatic cancer is relatively rare and accounts for only 3% of incident cancer cases in the United States, it is among the most lethal of all major cancers, with a 5-year survival rate of only 10%. Pancreatic ductal adenocarcinoma (PDAC) is the most common pancreatic cancer type and accounts for more than 85% of pancreatic cancers. Potentially modifiable risk factors for PDAC include cigarette smoking, excess body weight, type 2 diabetes mellitus, and diet. In studies of individual nutrients or foods and PDAC risk, the most consistently reported associations have been for higher PDAC risk with heavy alcohol use[4–6] and inconsistent associations for higher consumption of red meat and dietary fat.[7–10]
In contrast to individual foods and nutrients, dietary patterns can account for complex correlations and interactions that are not detected when evaluating associations for individual foods or nutrients. The Dietary Patterns Methods Project identified the 4 most commonly used a priori–defined US diet quality indices: the Healthy Eating Index (HEI),[12,13] based on the Dietary Guidelines for Americans; Alternative HEI (AHEI), based on Harvard's Healthy Eating Plate; alternate Mediterranean diet score (aMed), based on the Mediterranean Diet; and Dietary Approaches to Stop Hypertension (DASH), based on the DASH Eating Plan.[20–22] These patterns emphasize higher consumption of fruits, vegetables, whole grains, and legumes and limited consumption of refined grains, red and processed meats, sugar-sweetened beverages, added sugars, and saturated fats. Accumulating evidence suggests that greater adherence to these diet quality indices is associated with lower risk of cancer incidence and mortality.[23,24]
Three prospective studies have evaluated the association between aMed and HEI-2005 indices and pancreatic cancer risk with conflicting results.[25–27] Since the publication of the earlier studies of diet and PDAC risk within National Institutes of Health (NIH)-AARP (formerly the American Association of Retired Persons),[26,28] there has been longer follow-up and more incident PDAC cases. To compare variations between diet indices and PDAC risk, we examined the associations between adherence scores to 5 sets of diet quality index recommendations. To be consistent with the Dietary Patterns Methods Project, in this analysis, we considered the HEI-2015,[12,13] AHEI-2010, aMed, and 2 DASH diet indices, one based on food groups (Fung et al.) and the other based on nutrients (Mellen et al.). To the best of our knowledge, HEI-2015, AHEI-2010, and the 2 DASH scores have not previously been examined and compared in relation to PDAC risk. We hypothesized that greater adherence to diet quality indices would be associated with lower PDAC risk.
Am J Epidemiol. 2022;191(9):1584-1600. © 2022 Oxford University Press