Post-diagnosis dietary insulinemic potential and survival outcomes among colorectal cancer patients

BACKGROUND: The empirical dietary index for hyperinsulinemia (EDIH) score is a validated food-based dietary score that assesses the ability of whole-food diets to predict plasma c-peptide concentrations. Although the EDIH has been extensively applied and found to be predictive of risk of developing major chronic diseases, its influence on cancer survival has not been evaluated. We applied the EDIH score in a large cohort of colorectal cancer patients to assess the insulinemic potential of their dietary patterns after diagnosis and determine its influence on survival outcomes. METHODS: We calculated EDIH scores to assess the insulinemic potential of post-diagnosis dietary patterns and examined survival outcomes in a sample of 1718 stage I-III colorectal cancer patients in the Nurses’ Health Study and Health Professionals Follow-up Study cohorts. Multivariable-adjusted Cox regression was applied to compute hazard ratios (HR) and 95% confidence intervals (CI) for colorectal cancer-specific mortality and all-cause mortality. We also examined the influence of change in diet from pre- to post-diagnosis period, on mortality. RESULTS: During a median follow-up of 9.9 years, there were 1008 deaths, which included 272 colorectal cancer-specific deaths (27%). In the multivariable-adjusted analyses, colorectal cancer patients in the highest compared to lowest EDIH quintile, had a 66% greater risk of dying from colorectal cancer: HR, 1.66; 95% CI, 1.03, 2.69; and a 24% greater risk of all-cause death: HR, 1.24; 95%CI, 0.97, 1.58. Compared to patients who consumed low insulinemic diets from pre- to post-diagnosis period, patients who persistently consumed hyperinsulinemic diets were at higher risk of colorectal cancer death (HR,1.51; 95%CI, 0.98, 2.32) and all-cause death (HR, 1.31; 95%CI, 1.04, 2.64). CONCLUSION: Our findings suggest that a hyperinsulinemic dietary pattern after diagnosis of colorectal cancer is associated with poorer survival. Interventions with dietary patterns to reduce insulinemic activity and impact survivorship are warranted.