Pancreatic cancer is one of the deadliest cancers that affect the pancreas, an organ located behind the stomach. It occurs when abnormal cells in the pancreas start to grow out of control, forming a tumor. The early stages of pancreatic cancer usually do not cause any symptoms. As the tumor grows, it can cause symptoms such as abdominal pain, back pain, weight loss, loss of appetite, and jaundice. These symptoms can be caused by other conditions as well, so it is important to see a doctor if you experience any of them.