Association between pre- and post-diagnosis healthy eating index 2020 and ovarian cancer survival: evidence from a prospective cohort study.

: Previous studies on the association between diet quality and ovarian cancer (OC) survival are limited and inconsistent. We evaluated the relationship between pre- and post-diagnosis diet quality based on the Healthy Eating Index-2020 (HEI-2020), as well as their changes and OC survival. : This prospective cohort study involved 1082 patients with OC aged 18-79 years, enrolled between 2015 and 2022. Detailed dietary intake before and after diagnosis was recorded using a validated food frequency questionnaire. Deaths were ascertained until February 16th, 2023 medical records and active follow-up. Cox proportional hazards regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CI). : We included 549 OC cases with a median follow-up of 44.9 months, representing 206 total deaths. Higher HEI scores were associated with better OS (pre-diagnosis: HR 0.66, 95%CI: 0.46-0.93, HR 0.84, 95%CI: 0.73-0.96; post-diagnosis: HR 0.68, 95%CI: 0.49-0.96, HR 0.80, 95%CI: 0.69-0.92). Compared to the stable group, the group with decreased HEI scores (>3%) from pre- to post-diagnosis had worse OS (HR 1.93, 95%CI: 1.26-2.97). : High pre- and post-diagnosis diet quality was associated with improved OC survival, whereas deterioration in diet quality after diagnosis was associated with decreased OC survival.