Supplementary Material for 'Meta-analysis of the relationship between dietary inflammatory index and upper gastrointestinal cancer risks'

We systematically searched PubMed, Web of Science, Cochrane Library, Embase, CNKI, Wanfang and VIP databases from established databases to October 10, 2022. Two researchers searched independently according to the retrieval strategy, using the principle of combining subject words with free words. At the same time, literature retrospective search and obtain the original text. When reading literature and review, the reference of the obtained literature should be searched one by one to avoid missing inspection. Meta-analysis was performed using RevMan 5.4.1 software provided by Cochrane Collaboration. OR and 95%CI were considered as effect sizes for all studies. The chi-square test was used to analyze the heterogeneity of the included studies. The test level was α=0.1, when I2≤50%, P> 0.1, the fixed effect model was used for small heterogeneity. When the I2 >50%, P ≤ 0.1, the random effects model was used for higher heterogeneity. At the same time, subgroup analysis was performed to explore the source of heterogeneity adjusted by cancer site, study region, age, the number of DII components, and total energy intake adjusted. The funnel plot was used to visually judge the publication bias, and sensitivity analysis was used to evaluate the stability of the results. Each study was excluded one by one to observe the potential impact of each study on the combined effect size.