The causal relationship between drinking water and gastrointestinal cancers: a two‐sample mendelian randomization analysis

Abstract Cancers of the digestive tract are a series of diseases that seriously affects the health and life quality of the population worldwide, and the etiology is closely related to various daily habits. Drinking water is a daily human activity, but the intrinsic connection between water intake and gastrointestinal (GI) cancers is still unclear. We used the two‐sample mendelian randomization (TSMR) method to explore the potential causal relationship between water consumption and GI cancers. We obtained the integrated GWAS data of water intake (ukb‐b‐14 898), as well as the GWAS results of oral cavity cancer (ieu‐b‐4961), esophageal cancer (ebi‐a‐GCST90018841), gastric cancer (ebi‐a‐GCST90018849), liver cancer (ieu‐b‐4953), hepatic bile duct cancer (ebi‐a‐GCST90018803), pancreatic cancer (ebi‐a‐GCST90018893) and colorectal cancer (ebi‐a‐GCST90018588) through the online database “IEU OPEN GWAS PROJECT”. Using inverse variance weighting (IVW) method, weighted median method, MR Egger regression method, simple model method, and weighted model method to jointly study the causal relationship between water intake and GI cancers. Mendelian randomization analysis showed a negative correlation between water consumption and esophageal cancer (weighted media, OR = 0.215, p = .021; MR Egger, OR = 0.033, p = .040; weighted mode, OR = 0.162, p = .045), a positively association with pancreatic cancer (IVW, OR = 2.663, p = .033). There is a potential positive correlation between water intake and gastric cancer as well as colorectal cancer, but not statistically significant. The associations between water intake and oral cavity cancer, liver cancer and hepatic bile duct cancer remain uncertain. Therefore, Increased amount of drinking water may help to prevent the incidence of esophageal cancer, but might promote the development of pancreatic cancer.