Cancer is a disease in which cells grow in an abnormal way. Normally, the cells divide in a controlled manner. If cells keep dividing when new cells are not needed, a tumor forms.
A tumor can be benign or malignant. A benign tumor is not cancer. It will not spread to other parts of the body. A malignant tumor is cancer. Cancer cells spread and cause damage around them. They can also enter the lymph and blood streams. This makes it easier to spread cancer to other parts of the body.
Normal Anatomy and the Development of Pancreatic Cancer
The pancreas sits behind and to the right of the stomach. It's near the liver, gallbladder, and intestines. The pancreas is part of the digestive system. It plays a central role in breaking down food so it can be used by the body for energy.
There are 3 parts:
- Head—on the right side, closest to the first part of the small intestine
- Body—in the middle, located behind the stomach
- Tail—on the left side, closest to the spleen
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The pancreas is made up of 2 types of cells. These are the endocrine and exocrine. The endocrine, or islet cells, make many hormones. Hormones enter the bloodstream and travel throughout the body. They help control many functions, and balance how the body works. The pancreas makes insulin. Insulin breaks down and uses or stores sugars from food.
The exocrine cells make digestive juices. These juices help break down food in the small intestine. They travel from the pancreas through a system of ducts. These digestive juices help break down fat, protein, and carbohydrates in food.
Tumors can cause blocks. If digestive juices or insulin are blocked, you may not get enough nutrition even when eating as you should. If the tumor grows beyond the pancreas, the cancer can pass into nearby structures. The cancer can interfere with how other structures work as well. The cancer can also spread to lymph nodes or blood vessels. When it does, it spreads to other parts of the body. The most common sites are the lining of the belly, liver, and lungs.
Types of Pancreatic Cancer
There are many types of pancreatic cancer. They're based on the cell type and where the cancer starts. The types are:
- Ductal adenocarcinoma—Starts and grows in the ducts that pass digestive juices. This type makes up nearly all pancreatic cancers.
- Acinar cell carcinoma—Arise from the exocrine cells that make pancreatic enzymes for digestion. There are other, more rare types of exocrine cancers. They are named for where they start and how they look when tested in a lab:
- Adenosquamous carcinoma
- Squamous cell carcinoma
- Signet ring cell carcinoma
- Undifferentiated carcinoma with or without giant cells
- Pancreatic neuroendocrine tumors (PanNET)—Come from the islet cells. These can also be benign, but it is often hard to know. Sometimes, cancer can't be diagnosed until the tumor spreads from the original site. There are different types of PanNets:
- Functioning—Make up half of PanNet tumors. They make hormones and can be found in the digestive tract. They are named for the hormone that is produced by the tumor cells such as gastrinoma (stomach) or insulinoma (pancreas).
- Non-functioning—Tumors don't cause symptoms because they don't make enough excess hormones. As a result, they may not be found until they grow to a large size.
- Ampullary—Starts in the part of the bile duct where it empties into the small intestine. For the most part, it's found earlier than other types.
This fact sheet is about ductal adenocarcinoma.