Insulinemic and Inflammatory Dietary Patterns and Risk of Prostate Cancer.

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.