Prospective Cohort of Pre- and Post-diagnosis Diet with Survival Outcomes: an Alberta Endometrial Cancer Cohort Study


 Background: The prognostic relationship between diet and endometrial cancer survival remains largely unknown. We sought to determine pre- and post-diagnosis dietary composition, glycemic load (GL), inflammatory potential (Dietary Inflammatory Index (DII)) and quality (Canadian-Health Eating Index (C-HEI) 2005) associations with disease-free (DFS) and overall survival (OS) among endometrial cancer survivors. Additionally, we assessed associations between dietary changes with OS and explored obesity/physical activity effect modification. Methods: Survivors, diagnosed in Alberta, Canada between 2002-2006, completed past-year, food-frequency questionnaires at-diagnosis (n=503) and three-year follow-up (n=395). Participants were followed to death or January 2022. Cox proportional regression estimated HR (95% confidence intervals (CIs)) for dietary survival associations. Results: During 16.9 median years of follow-up, 138 participants had a DFS event and 120 died. Lower pre-diagnosis GL (HRT1vsT3=0.49, 95%CI=0.25-0.97) and greater post-diagnosis energy intakes (EI) from total- and monounsaturated-fat (HRT3vsT1=0.48, 95%CI=0.26-0.87) were associated with better OS. Higher pre-diagnosis C-HEI, less inflammatory diets and lower added sugar intakes were non-linearly associated with better DFS. Consistently low pre-to-post diagnosis EI from carbohydrates and total-fats were associated with better (HR=0.36, 95%CI=0.18-0.72) and worse (HR=2.26, 95%CI=1.21-4.20) OS, respectively. Decreased pre-to-post diagnosis C-HEI was associated with worse OS. In stratified analysis, healthy diets were most beneficial for survivors with obesity and physical inactivity. Conclusion: Adherence to higher quality dietary patterns were associated with better survival. Impact: Our study provides novel evidence that both pre- and post-diagnosis diet are important prognostic factors for endometrial cancer survivors. Post-diagnosis survival associations with diet composition and quality highlight the potential for future interventions.