Pancreatic cancer can be caused by several factors, many of which increase the risk though the exact cause is often unclear. Key causes and risk factors include:

• Smoking tobacco, which is one of the most significant risk factors and doubles the risk of pancreatic cancer. About 20-25% of cases are linked to smoking.
• Chronic inflammation of the pancreas (chronic pancreatitis), often related to heavy alcohol use and smoking.
• Diabetes, particularly type 2 diabetes, is associated with an increased risk, though the reason is not fully understood.
• Obesity and carrying excess weight, especially around the abdomen, increase risk by about 20%.
• Family history and inherited genetic mutations (such as mutations in BRCA genes, Lynch syndrome, and others) can raise pancreatic cancer risk.
• Older age, with most cases occurring in people over 65 or 75.
• Exposure to certain workplace chemicals like those used in dry cleaning and metal work.
• Poor nutrition, including diets high in red and processed meat, may also contribute to risk.

Overall, pancreatic cancer arises from DNA changes in pancreatic cells causing uncontrolled growth, but many risk factors influence these genetic mutations.