Dietary Fats, Serum Cholesterol and Liver Cancer Risk: A Systematic Review and Meta-Analysis of Prospective Studies

SIMPLE SUMMARY: Due to the rapid increase of primary liver cancer incidence and the poor prognosis, it is imperative to identify new modifiable factors such as diet and nutrition for the prevention of liver cancer. Diet high in saturated fatty acids (SFA) has been hypothesized to be associated with increased risk of cancers. However, the associations between dietary fatty acids and liver cancer are not consistent. We aimed to examine the association between dietary total fat, its major components, serum cholesterol, and risk of liver cancer combining current evidence from prospective studies. Our meta-analyses provided new evidence on associations between dietary fats, serum cholesterol, and liver cancer risk. Higher intake of dietary SFA was associated with higher risk of liver cancer while higher serum levels of cholesterol and high-density lipoprotein (HDL) were associated with a lower risk of liver cancer with high between-studies variability. Based on our findings, reducing dietary SFA may help to prevent the development of liver cancer. ABSTRACT: To quantify the associations between dietary fats and their major components, as well as serum levels of cholesterol, and liver cancer risk, we performed a systematic review and meta-analysis of prospective studies. We searched PubMed, Embase, and Web of Science up to October 2020 for prospective studies that reported the risk estimates of dietary fats and serum cholesterol for liver cancer risk. We carried out highest versus lowest intake or level and dose-response analyses. Higher intake of dietary saturated fatty acids (SFA) was associated with a higher liver cancer risk in both category analysis (relative risk [RR](highest vs. lowest intake) = 1.34, 95% confidence interval [CI]: 1.06, 1.69) and dose-response analysis (RR(1% energy) = 1.04, 95%CI: 1.01, 1.07). Higher serum total cholesterol was inversely associated with liver cancer but with large between-studies variability (RR(1 mmol/L) = 0.72, 95%CI: 0.69, 0.75, I(2) = 75.3%). The inverse association was more pronounced for serum high-density lipoprotein (HDL) cholesterol (RR(1 mmol/L) = 0.42, 95%CI: 0.27, 0.64). Higher intake of dietary SFA was associated with higher risk of liver cancer while higher serum levels of cholesterol and HDL were associated with a lower risk of liver cancer with high between-studies variability.