Cancer is an uncontrolled growth of abnormal cells that form tumors, damage normal tissue, and that may eventually metastasize (spread throughout the body). Most (95%) pancreatic cancers develop in the pancreatic ducts and sometimes develop in the enzyme-producing cells of the exocrine pancreas. Endocrine pancreatic tumors are usually less aggressive than exocrine tumors and are rarer. They may be benign tumors (those that do not metastasize, such as insulinomas) or malignant (a group of cancers called islet cell cancers). They often are detected earlier than exocrine cancers because they tend to produce excessive amounts of the hormones insulin and glucagon.

Because they are more common and aggressive, the remainder of this discussion focuses on exocrine cancer. Unfortunately, these cancers are hard to detect at an early stage. Since the pancreas is deep in the body, tumors that develop cannot usually be seen or felt during a physical examination and by the time symptoms develop, the cancer has often spread throughout the pancreas and beyond. One exception to this is ampullary cancer, a cancer that forms where the pancreatic and bile duct empty into the duodenum. Since ampullary cancer often obstructs the flow of bile from the bile duct and causes jaundice, it has the potential of being detected earlier than most exocrine cancers.

According to the American Cancer Society, 33,730 Americans will be diagnosed with pancreatic cancer in 2006 and an estimated 32,300 will die. It is the fourth leading cause of cancer death in the United States, primarily because only about 10% of the cancers are still contained within the pancreas at the time of diagnosis.