Intakes of citrus fruit and risk of esophageal cancer: A meta-analysis

Esophageal cancer (EC) is the eighth most common cancer and the sixth most frequent cause of cancer death in the whole world. Many studies have investigated the association between citrus fruit intake and the risk of EC, but the results are inconsistent and not analyzed by category. We aimed to perform a meta-analysis of studies to evaluate the incidence between citrus fruit consumption and subtypes of esophageal cancer and derive a more precise estimation. Through searches of PubMed, OVID, and Web of Science we updated 1988 systematic review up to April 2016. Based on an inclusion and exclusion criteria, conventional meta-analysis according to DerSimonian and Laird method was used for the pooling of the results. Random-effect models were used to calculate subgroups. Twenty-five English articles (20 case-control studies and 5 cohort studies) comprising totally 5730 patients of esophageal cancer would be suitable for use in this study. The result indicated the inverse associations between intakes of citrus fruit and EC (relative risk [RR] = 0.65, 95% confidence interval [CI] 0.56−0.75, I(2) = 51.1%, P = .001), Esophageal squamous cell carcinoma (ESCC) (RR = 0.59, 95% CI 0.47–0.76, I(2) = 60.7%, P = .002), no significant relationship between citrus fruit and esophageal adenocarcinoma (EAC) (RR = 0.86, 95% CI 0.74–1.01, I(2) = 0.0%, P = .598). This meta-analysis indicates that intakes of citrus fruit significantly reduce the risk of ESCC and is no obvious relationship with EAC. Further studies about constituents in citrus fruit and its mechanism are warranted.