High-density lipoprotein, low-density lipoprotein and triglyceride levels and upper gastrointestinal cancers risk: a trans-ancestry Mendelian randomization study

This study was conducted to explore the causal associations of high-density lipoprotein (HDL), low-density lipoprotein (LDL) and triglyceride (TG) with the risk of upper gastrointestinal cancers (esophageal cancer [EC] and gastric cancer [GC]).A total of 5623 Chinese and 4133 Europeans afforded the individual-level genotyping data, and 203,608 Japanese from Biobank Japan project and 393,926 Europeans from UK Biobank supported summary statistics of cancer genetic associations. Mendelian randomization (MR) analyses, including weighted genetic risk scores (wGRSs), inverse-variance weighted (IVW), weighted median and Egger-regression, were utilized to evaluate the causal effects of three blood lipids on upper gastrointestinal cancers risk.There was no significantly causal relationships between three blood lipids and EC or GC risk among Chinese or Europeans but a potential causal association between TG and GC risk among Japanese (IVW: odds ratio [OR] = 1.11, P = 0.034; Phet = 0.679). In stratified subgroups, higher genetically predicted TG levels were causally associated with an increased risk of GC among Chinese males (wGRS: OR = 1.61, P = 0.021; IVW: OR = 1.57, P = 0.009; Phet = 0.653) and Japanese females (IVW: OR = 1.33, P = 0.024; Phet = 0.378).This trans-ancestry MR study suggested null significant causality between serum HDL, LDL or TG and the risk of upper gastrointestinal cancers among Chinese and Europeans, but provided evidence for a causal role of TG involved in GC etiology in Japanese (especially females), which would support a prevention guide for high-risk groups of GC. Further research with more comprehensive information is needed to explore the underlying mechanism.