Cumulative Evidence for Relationship Between Body Mass Index and Risk of Esophageal Cancer: An Updated Meta‐Analysis with Evidence from 25 Observational Studies

BACKGROUND AND AIM: A large number of papers reporting the relationships between body mass index (BMI) and esophageal cancer (EC) risk have been published in the past few decades, however, these result are inconsistent. Therefore, we carried out meta-analyses to explore the relationships between BMI and risk of EC (including esophageal squamous cell carcinoma (ESCC) and esophageal adenocarcinoma (EADC)). METHODS: We used the Web of science, PubMed and Embase to identify all published/online articles before December 30th, 2018, which yielded 25 articles eligible for data extraction (including 16,561 cases and 11,954,161 controls), and then pooled the relative risks (RRs) and corresponding 95% confidence intervals (CIs) using random-effects model. RESULTS: Our study presented that underweight had statistically significant association with risk of EC (RR = 1.78, 95%CI = 1.48-2.14, p<0.001) and ESCC (RR = 1.57, 95%CI = 1.20-2.06, p = 0.001) when compared with normal weight. Interestingly, both overweight and obesity could increase risk of EADC (RR = 1.56, 95%CI = 1.42-1.71, p<0.001; RR = 2.34, 95%CI = 2.02-2.70, p<0.001) while decrease risk of ESCC (RR = 0.71, 95%CI = 0.60-0.84, p<0.001; RR = 0.63, 95%CI = 0.60-0.84, p = 0.002). Additionally, obesity could increase risk of EC (RR = 1.51, 95%CI = 1.21-1.89, p<0.001). CONCLUSION: This meta-analyses provides a comprehensive and updated epidemiological evidence to confirm the associations between BMI and EC risk. These findings have public health implications with respect to better control body weight, and then reduce the occurrence of EC (including ESCC and EADC).