Pancreatic Cancer: Introduction
What is cancer?
Cancer starts when cells in the body change (mutate) and grow out of control. Your
body is made up of tiny building blocks called cells. Normal cells grow when your
body needs them. They die when your body doesn't need them any longer.
Cancer is made up of abnormal cells that grow even though your body doesn't need them.
In most cancers, the abnormal cells grow to form a lump or mass called a tumor. If
cancer cells are in the body long enough, they can grow into (invade) nearby tissues.
They can even spread to other parts of the body (metastasize).
What is pancreatic cancer?
Pancreatic cancer is cancer that starts in your pancreas. Normal cells in the pancreas
go through a series of changes that make them stop acting like normal cells. Over
time, this can lead to excess cell growth and tumors can form.
Understanding the pancreas
The pancreas is a gland. It's an organ that makes substances the body needs. It makes
two important things:
Your pancreas is in your left upper belly (abdomen) behind your stomach. It’s about
6 inches long. The end, toward the middle of your abdomen, is wide and is called the head. The
middle is called the body. The narrow end is called the tail.
The pancreas is made up of two main types of cells:
The exocrine pancreas is made up of cells that make digestive juices. These help your body break down foods.
Most pancreatic cancers start in this part of the pancreas. Pancreatic juices contain
chemicals called enzymes that help break down food. The pancreas releases these enzymes
during meals. The enzymes go into your intestine through small tubes called ducts. The
main pancreatic duct is at the head of the pancreas. It joins the common bile duct, which
comes from the liver and gallbladder. The enzymes from the pancreas mix with other
substances coming from the liver and gallbladder. The merged ducts open into the first
part of the small intestine (called the duodenum). In the duodenum, the enzymes help
break down fats, sugars, and proteins in the food you eat.
The endocrine pancreas makes many hormones that are released into the blood. They help control how your
body works. The pancreatic endocrine cells are arranged in small clumps called islets
of Langerhans. Two important hormones made here are insulin and glucagon. These hormones
help your body use and store the energy created from the food you eat. A small number
of all pancreatic cancers start in endocrine cells.
What are the types of cancer in the pancreas?
There are two main types of cancer that can start in the pancreas:
Adenocarcinomas. These start in the exocrine pancreas cells that make up the pancreatic ducts or,
less often, the cells that secrete digestive enzymes. About 95 out of 100 pancreatic
cancers are adenocarcinomas. When people use the term pancreatic cancer, they usually
mean this type.
Pancreatic neuroendocrine tumors (PNETs). These tumors are also called islet cell tumors. They start in endocrine cells in
the pancreas. There are many types of PNETs. They're named based on the type of hormone
they make. They can be non-cancer (benign) or cancer (malignant). Fewer than 10 out
of 100 pancreatic cancers are PNETs.
Other types of cancer that can start in the pancreas are much less common. They include
rare exocrine cancers like acinar cell carcinomas, adenosquamous carcinomas, squamous
cell carcinomas, signet ring cell carcinomas, and giant cell tumors.
How pancreatic cancer grows and spreads
Pancreatic cancer often grows within the pancreas for a long time before it causes
any symptoms. If the cancer grows outside the pancreas, it often goes into the nearby
bile ducts and lymph nodes in your belly (abdomen). Sometimes it spreads to other
nearby tissues. Pancreatic cancer may also spread to distant parts of the body. These
can include your liver or lungs.
When pancreatic cancer spreads to another part of the body, it’s not a new cancer.
For instance, if it spreads to the liver, it’s not called liver cancer. It’s called
metastatic pancreatic cancer. The cancer cells in the liver look like, act like, and
are treated like pancreatic cancer.
Talk with your healthcare provider
If you have questions about pancreatic cancer, talk with your healthcare provider.
Your healthcare provider can help you understand more about this cancer.