Associations of pre- and post-diagnosis dietary macronutrient quality and its changes with ovarian cancer survival: evidence from a prospective cohort study

Associations of post-diagnosis dietary macronutrient quality and its changes from pre- to post-diagnosis with ovarian cancer (OC) survival remains unknown. It is necessary to investigate this topic due to the urgent need for specific guidance on dietary macronutrients from pre- to post-diagnosis for patients with OC. This study aimed to comprehensively evaluate associations of pre- and post-diagnosis dietary macronutrient quality and its changes with overall survival (OS) of OC, using a multidimensional macronutrient quality index (MQI). The prospective cohort study included 1082 patients with OC enrolled between 2015 and 2022. Dietary data were collected via a validated food frequency questionnaire. MQI was calculated on the basis of the carbohydrate quality index (CQI), fat quality index (FQI), and protein quality index (PQI). Deaths were tracked until February 16, 2023, through active follow-up, medical records, and death registries. Hazard ratio (HR) and 95% confidence interval (CI) were calculated using Cox proportional hazards regression models. Among the 542 OC cases included, there were 198 (36.53%) all-cause deaths over a median follow-up of 44.75 months (interquartile range: 28.53–62.23 months). Higher MQI was associated with lower all-cause mortality (pre-diagnosis: HRT3 vs. T1=0.52, 95%CI: 0.36–0.75; post-diagnosis: HRT3 vs. T1=0.65, 95%CI: 0.46–0.94). Pre-diagnosis FQI (HRT3 vs. T1=0.44, 95%CI: 0.30–0.64) and PQI (HRT3 vs. T1=0.65, 95%CI: 0.46–0.94), and post-diagnosis CQI (HRT3 vs. T1=0.63, 95%CI: 0.43–0.92) were positively associated with OS. Patients with OC who consistently consumed diets with high MQI, FQI, and PQI from pre- to post-diagnosis exhibited superior OS compared to those maintaining diets with low MQI, FQI, and PQI, respectively (MQI: HRHigh-High vs. Low-Low = 0.55, 95%CI: 0.37–0.82; FQI: HRHigh-High vs. Low-Low = 0.52, 95%CI: 0.35–0.76; PQI: HRHigh-High vs. Low-Low = 0.58, 95%CI: 0.40–0.83). Improved dietary macronutrient quality both before and after diagnosis was associated with lower all-cause mortality, with further improvements from pre- to post-diagnosis being associated with improved OS in OC patients.