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) and quality [Canadian Healthy Eating Index (C-HEI) 2005] asso-ciations with disease-free (DFS) and overall survival (OS) among endometrial cancer survivors. In addition, we assessed associations between dietary changes with OS and explored obesity/physical activity effect modification.Methods: Survivors, diagnosed in Alberta, Canada between 2002 and 2006, completed past-year, food-frequency questionnaires at -diagnosis (n = 503) and 3-year follow-up (n = 395). Participants were followed to death or January 2022. Cox proportional regres-sion estimated HR [95% confidence intervals (CI)] 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 nonlinearly 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.Conclusions: 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 endo-metrial cancer survivors. Post-diagnosis survival associations with diet composition and quality highlight the potential for future interventions.