Association of plant-based diets with risk of upper gastrointestinal tract cancers:A systematic review and meta-analysis

Background:Diets rich in red or processed meat have been linked to an increased risk of cancers within the digestive system.It has been suggested that a plant-based diet may have protective effects against digestive system cancers.This study aimed to determine the association between plant-based diets and upper gastrointestinal tract cancers(UGTCs).Methods:We conducted a systematic review and meta-analysis of observational studies.We searched the PubMed,MEDLINE,Embase,and Web of Science databases for articles published up to September 30,2023.We pooled the risk ratios(RRs) with the corresponding95% confidence intervals(CIs) using fixed-or random-effects models.Results:Our meta-analysis included 16 studies(30 results).The data revealed a strong inverse association between a high intake of plant-based diets and UGTC(RR=0.60,95% CI=0.49-0.72),specifically gastric cancer(GC,RR=0.53,95% CI=0.42-0.67) and esophageal cancer(EC,RR=0.63,95% CI=0.42-0.96).This relationship was not significant for gastric cardia cancer(GCA) or esophagogastric junctional cancer(EGJC,RR=0.76,95% CI=0.47-1.22).A subgroup analysis showed the association was significant in studies from Asia and Europe,as well as in studies utilizing indices such as a vegetarian diet,Mediterranean diet,the Plant-Based Diet Index,and principal component analysis dietary patterns.There was no indication of publication bias among the analyzed studies.Conclusions:This meta-analysis highlights the potential health benefits of plant-based diets in preventing UGTC,particularly regarding esophageal squamous cell carcinoma(ESCC) and GC.Nevertheless,additional research is required to validate these results and explore the underlying mechanisms.