Pancreatic cancer is one of the common malignant tumors of the digestive tract, mostly occurring in the head of the pancreas, called pancreatic head cancer, but there are also cancers occurring in the body of the pancreas, but they are less common. Abdominal pain and painless jaundice are the common symptoms of pancreatic head cancer. Surgery to remove the cancer is the effective treatment for pancreatic head cancer. 90% of patients die within one year after diagnosis, and the 5-year survival rate is only 1-3%. So, what are the causes of pancreatic cancer? The following are the causes of the development of pancreatic cancer Smoking: A large number of studies support a close link between pancreatic cancer and smoking. Possible mechanisms of pancreatic cancer caused by smoking: 1. Smoking prompts the secretion of carcinogenic tobacco-specific N-nitrite into the bile duct, which subsequently backflows into the pancreatic duct; 2. The specific effect of tobacco-specific N-nitrite on organs can flow into the pancreas with blood; 3. Smoking increases blood lipid levels and promotes pancreatic cancer. Experiments by Stolzenberg et al. confirmed that maintaining adequate concentrations of folic acid and pyridoxal reduces the risk of smoking-related pancreatic cancer. Second, chronic pancreatitis: most of the epidemiological and molecular epidemiological studies support that chronic pancreatitis can develop into pancreatic cancer. the study by Friess showed that out of 5600 genes, 34 genes had reduced expression in patients with pancreatic cancer and chronic pancreatitis, 157 genes had enhanced expression in chronic pancreatitis, and 152 of these genes also had enhanced expression in pancreatic cancer. This study demonstrates at the molecular level that there may be some link between chronic pancreatitis and pancreatic cancer. Alcohol consumption: The incidence of pancreatic cancer varies among different races after drinking alcohol. According to a study by Silverman et al. who observed the relationship between alcohol consumption and the incidence of pancreatic cancer in black and white Americans, black male alcoholics and female moderate drinkers had a higher incidence compared to whites. Four, coffee: The survey found that coffee can increase the risk of pancreatic cancer by four times. Studies have proven that coffee can inhibit DNA repair and induce the mitotic process before DNA replication is completed, which is the main cause of cancer. Diabetes: Experimental studies have shown that insulin can promote the growth of pancreatic cancer cells in vitro or in vivo; high concentrations of insulin can activate insulin-like growth factor-1 receptors, producing growth-promoting effects including changes in cell cycle processes. VI. Helicobacter pylori (Hp): Studies have shown that there are Hp seropositive results in patients with pancreatic cancer, with significant differences compared to controls, suggesting a correlation between Hp infection and pancreatic cancer. The relationship between genes and pancreatic cancer developmentNotch, ras, p53, TGF-β, DPC4, apoptosis-related genes have a complex role in pancreatic cancer, but the exact mechanism is not clear. Tumorigenesis and progression is a complex multi-stage process resulting from malfunctioning expression of multiple tumor-associated genes or inactivation of many tumor suppressor genes. DNA microarray technology can directly detect the type and abundance of mRNA, which is a powerful tool to study gene expression.