Adherence to 5 Diet Quality Indices and Pancreatic Cancer Risk in a Large US Prospective Cohort

Sachelly Julián-Serrano; Jill Reedy; Kim Robien; Rachael Stolzenberg-Solomon

Disclosures

Am J Epidemiol. 2022;191(9):1584-1600. 

In This Article

Abstract and Introduction

Abstract

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.

Introduction

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%.[1] Pancreatic ductal adenocarcinoma (PDAC) is the most common pancreatic cancer type and accounts for more than 85% of pancreatic cancers.[2] Potentially modifiable risk factors for PDAC include cigarette smoking, excess body weight, type 2 diabetes mellitus, and diet.[3] 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.[11] 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;[14] Alternative HEI (AHEI),[15] based on Harvard's Healthy Eating Plate;[16] alternate Mediterranean diet score (aMed),[17] based on the Mediterranean Diet;[18] and Dietary Approaches to Stop Hypertension (DASH),[19] 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,[24] in this analysis, we considered the HEI-2015,[12,13] AHEI-2010,[15] aMed,[17] and 2 DASH diet indices, one based on food groups (Fung et al.)[19] and the other based on nutrients (Mellen et al.).[29] 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.

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