Cohort study of 46 804 men (Health Professionals Follow-up Study: 1986-2012) and 74 246 women (Nurses' Health Study: 1984-2012) followed for 26 years to examine associations between EDIP scores and
colorectal cancer risk using Cox regression. We also examined associations in categories of alcohol intake and
body weight. Data analysis began January 17, 2017, and was completed August 9, 2017.
EXPOSURES: EDIP scores calculated from food frequency questionnaires administered every 4 years.
MAIN OUTCOMES AND MEASURES: We documented 2699 incident
colorectal cancer cases over 2 571 831 person-years of follow-up. Compared with participants in the lowest EDIP quintile (Q) who had a
colorectal cancer incidence rate (per 100 000 person-years) of 113 (men) and 80 (women), those in the highest Q had an incidence rate of 151 (men) and 92 (women), leading to an unadjusted rate difference of 38 and 12 more
colorectal cancer cases, respectively, among those consuming highly proinflammatory diets. Comparing participants in the highest vs lowest EDIP Qs in multivariable-adjusted analyses, higher EDIP scores were associated with 44% (men: hazard ratio [HR], 1.44; 95% CI, 1.19-1.74; P < .001 for trend), 22% (women: HR, 1.22; 95% CI, 1.02-1.45; P = .007 for trend), and 32% (men and women: pooled HR, 1.32; 95% CI, 1.12-1.55; P < .001 for trend) higher risk of developing
colorectal cancer. In both men and women, associations were observed in all anatomic subsites except for the rectum in women. In subgroups (P ≤ .02 for all interactions), associations differed by alcohol intake level, with stronger associations among men (Q5 vs Q1 HR, 1.62; 95% CI, 1.05-2.49; P = .002 for trend) and women (Q5 vs Q1 HR, 1.33; 95% CI, 0.97-1.81; P = .03 for trend) not consuming alcohol; and by
body weight, with stronger associations among
overweight/obese men (Q5 vs Q1 HR, 1.48; 95% CI, 1.12-1.94; P = .008 for trend) and lean women (Q5 vs Q1 HR, 1.31; 95% CI, 0.99-1.74; P = .01 for trend).
CONCLUSIONS AND RELEVANCE: Findings suggest that
inflammation is a potential mechanism linking dietary patterns and
colorectal cancer development. Interventions to reduce the adverse role of proinflammatory diets may be more effective among
overweight/obese men and lean women or men and women who do not consume alcohol.