Although its exact cause is not clear, the occurrence of pancreatic cancer has been reported to be related to the following factors 1. Smoking: Nitrosamines in cigarette are carcinogenic substances, which are activated after inhalation and transported to the liver through the bloodstream, and then refluxed into the pancreatic duct after being discharged into the bile. In addition, smoking can increase the concentration of blood lipids, which indirectly increases the risk of cancer. The incidence of pancreatic cancer in smokers is 2-2.5 times higher than in non-smokers, and the age of onset increases by 10-15 years. 2, diet: animal experiments have confirmed that a high protein diet is related to the occurrence of pancreatic cancer. In Japan, the incidence of pancreatic cancer has increased four times since 1950, which is related to the increase of animal protein and fat intake. High protein and high fat diets increase the rate of pancreatic cell renewal, thus increasing the sensitivity of the pancreas to carcinogens. High-fat and high-protein diets stimulate the release of cholecystokinin and other hormones from the gastrointestinal tract, thereby accelerating pancreatic cell renewal and increasing the sensitivity of the pancreas to carcinogens. The results of animal experiments showed that exogenous hormones such as cholecystokinin and glucagon can cause pancreatic hypertrophy and promote the development of pancreatic cancer in animals. Nitrosamines can induce pancreatic cancer in hamsters, while fat and protein intake can increase the sensitivity of animals to pancreatic cancer caused by nitrosamines. Fish oil in food can increase the pancreatic carcinogenic effect of diazoserine in rats. Improper storage and cooking of food can produce nitrosamines as carcinogens. In the cooking process, high temperatures can make the amino acids and proteins in meat and fish decompose heterocyclic aromatic amines with carcinogenic and mutagenic effects. In 1966, Burch et al. reported 83 cases of pancreatic cancer patients, 65% of whom had been drinking alcohol in medium or large quantities for 15 years, and only 15% of controls, thus proposing alcohol consumption as a risk factor for pancreatic cancer. Talamini et al. analyzed 630 patients with chronic pancreatitis (12 of whom developed pancreatic cancer), 69 patients with pancreatic cancer without a clinical history of chronic pancreatitis, and 6,000 patients with pancreatic cancer. The results showed that alcohol consumption and smoking were independent risk factors for chronic pancreatitis, but there was no significant correlation between alcohol consumption and pancreatic cancer. Fruits and fresh vegetables contain protease inhibitors that protect the body from pancreatic cancer. These factors can prevent the synthesis of oxygen, prevent the degradation of proteins into amino acids needed to rapidly divide cancer cells, or inhibit the synthesis of poly ADP – ribonucleic acid, thus reducing the damage to DNA. Therefore, low consumption of fruits and fresh vegetables may increase the incidence of pancreatic cancer. In addition, eating fried meat can also increase its incidence. Certain diseases are related to the increased incidence of pancreatic cancer: the incidence of pancreatic cancer in diabetic patients is about 2-4 times higher than that of the normal population. The incidence of pancreatic cancer in chronic pancreatitis with calcified foci is 100 times higher than that of the general population. The risk of pancreatic cancer 20 years after major gastric resection is 5-7 times higher than that of the general population, due to the loss of the regulatory function of the stomach to the pancreas so that it can not respond to harmful substances; the detoxification of the metabolism of the small intestine is also affected by the removal of the stomach, resulting in increased exposure of the pancreas to carcinogenic substances. 6.Occupational environment: workers working in chemical plants manufacturing naphthylamine and aniline. The incidence of pancreatic cancer is 5 times higher than that of general workers. According to another survey, the incidence of pancreatic cancer is also higher among workers who work in oleochemical and jewelry manufacturing. 7, pancreatic cancer and chronic pancreatitis: smoking is the most certain risk factor for pancreatic cancer, and patients with chronic pancreatitis are often smokers who drink a lot of alcohol, so it is believed that smoking is a common risk factor for both pancreatic cancer and chronic pancreatitis. Patients with chronic pancreatitis have an increased risk of not only pancreatic cancer, but also upper respiratory and gastrointestinal cancers, supporting the hypothesis that the two diseases have common risk factors. The mechanism of increased risk of pancreatic cancer in patients with chronic pancreatitis is not yet clear and may be related to the following factors: 1. Chronic inflammation of the pancreas damages its own biological barrier, allowing potential carcinogens to act. Sommers et al. first suggested that pancreatic ductal hyperplasia is associated with the development of pancreatic cancer. They found that 41% of 141 surgically resected pancreatic cancer specimens had hyperplasia. Among them, 4 – cases were found to have both simple hyperplasia, carcinoma in situ and invasive carcinoma. In addition, a series of mucinous cell proliferative lesions, including papillary and non-papillary proliferative lesions and atypical proliferative lesions, were found in the pathological examination of pancreatic ducts with chronic pancreatitis and pancreatic cancer. 3, The combination of K-Fas oncogene mutations and abnormal expression of epidermal growth factor and its ligands leads to the development and progression of pancreatic cancer. a meta-analysis of 5 studies on the incidence of chronic pancreatitis in patients with pancreatic cancer published from 1960 to 1990 showed that 10 out of 1078 cases of pancreatic cancer had chronic pancreatitis. Gambill found histological evidence of chronic pancreatitis in 10% of 255 patients with pancreatic cancer and periampullary carcinoma. Mikal et al. reported 49 cases of chronic pancreatitis at autopsy in 100 cases of pancreatic cancer. However, in surgical specimens with both cancer and chronic pancreatitis, it was not possible to determine the order of occurrence and causality of the two. It may be due to the increased risk of pancreatic cancer in chronic pancreatitis. Obstruction of the main pancreatic duct in the presence of pancreatic cancer also often leads to inflammation and fibrosis at the posterior end of the obstruction. In addition, there is often a nonspecific inflammatory response around the pancreatic cancer.