Pancreatic cancer arises when
cells in the
pancreas, a glandular organ behind the
stomach, begin to multiply out of control and form a
mass. These
cancerous cells have the
ability to invade other parts of the body. There are a number of types of pancreatic cancer. The most common,
pancreatic adenocarcinoma, accounts for about 85% of cases, and the term "pancreatic cancer" is sometimes used to refer only to that type. These
adenocarcinomas start within the part of the pancreas which make
digestive enzymes. Several other types of cancer, which collectively represent the majority of the non-adenocarcinomas, can also arise from these cells. One to two in every hundred cases of pancreatic cancer are
neuroendocrine tumors, which arise from the hormone-producing
cells of the pancreas. These are generally less aggressive than pancreatic adenocarcinoma.