What is the role of nonalcoholic fatty liver disease in pulmonary carcinoma development?

This article summarizes the epidemiological characteristics and clinical manifestations of nonalcoholic fatty liver disease (NAFLD). The incidence of NAFLD has been increased dramatically and become the leading cause of chronic liver disease worldwide. In addition to its adverse outcomes of liver fibrosis, cirrhosis, and hepatocellular carcinoma, and related complications, NAFLD has recently been found to be associated with the high-risk extrahepatic carcinomas, such as various types of lung cancer (i.e., lung adenocarcinoma, squamous cell carcinoma, and small cell lung cancer). The presence of hepatic steatosis also predisposes lung cancer to liver metastasis, but has better response to immune checkpoint inhibitors. Whether other factors (i.e., gender, smoking, etc.) are associated with NAFLD and lung cancer remains controversial. We also comment on the reciprocal relationships between NAFLD and components of metabolic syndrome. Most metabolic syndrome components are suggested to facilitate lung cancer development via activating insulin/insulin-like growth factor axis. In addition, suppressed anti-tumor immunity and accelerated tumor progression could be attributed to the cell-specific metabolic reprogramming in condition of high-fat diet and related obesity. These findings may reveal the role of NAFLD in pulmonary carcinoma and help develop new treatment strategies for this disease.