Insulinemic and Inflammatory Dietary Patterns and Risk of Prostate Cancer

Abstract

Background: Hyperinsulinemia and inflammation are inter-related pathways that link diet with the risk of several chronic diseases. Evidence suggests that these pathways may also increase prostate cancer risk.

Objective: To determine whether hyperinsulinemic diet and inflammatory diet are associated with prostate cancer incidence and mortality.

Design, setting, and participants: We prospectively followed 41 209 men in the Health Professionals Follow-up Study (1986-2014). Scores for two validated dietary patterns were calculated from food frequency questionnaires at baseline and updated every 4 yr.

Outcome measurements and statistical analysis: Total, advanced, and lethal prostate cancer outcomes were assessed. Multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were determined for associations between two empirical hypothesis-oriented dietary patterns-empirical dietary index for hyperinsulinemia and empirical dietary inflammatory pattern-and prostate cancer risk estimated using Cox proportional hazard regression.

Results and limitations: During 28 yr of follow-up, 5929 incident cases of total prostate cancer, including 1019 advanced and 667 fatal, were documented. In multivariable-adjusted models, there was a 7% higher risk of advanced prostate cancer (HR: 1.07; 95% CI: 1.01-1.15) and a 9% higher risk of fatal prostate cancer (HR: 1.09; 95% CI: 1.00-1.18) per standard deviation (SD) increase in the hyperinsulinemic diet. When stratified by age, the hyperinsulinemic diet was associated with only earlier-onset aggressive prostate cancer (men under 65 yr), with per SD HRs of 1.20 (95% CI: 1.06-1.35) for advanced, 1.22 (1.04-1.42) for fatal, and 1.20 (1.04-1.38) for lethal. The inflammatory diet was not associated with prostate cancer risk in the overall study population, but was associated with earlier-onset lethal prostate cancer (per SD increase HR: 1.16; 95% CI: 1.00-1.35).

Conclusions: Hyperinsulinemia and inflammation may be potential mechanisms linking dietary patterns with the risk of aggressive prostate cancer, particularly earlier-onset disease.

Patient summary: Avoiding inflammatory and hyperinsulinemic dietary patterns may be beneficial for the prevention of clinically relevant prostate cancer, especially among younger men.

Keywords: Cohort study; Diet; Hyperinsulinemia; Inflammation; Prostate cancer.