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 no longer needs them.
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 large gland. It is a part of the digestive system. 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 and below
the liver. It’s about 6 inches long in adults. The end, toward the middle of your
abdomen, is wide and is called the head. The middle is called the body. The narrow
end on the left side of your abdomen 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 food.
Most pancreatic cancers start in this part of the pancreas. Pancreatic juices contain
chemicals called enzymes that help break down food into substances your body can use.
The pancreas releases these enzymes during meals. The enzymes go into your small 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, starches, 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. Insulin helps
control the amount of sugar in your blood. 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:
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Adenocarcinomas. These start in the exocrine pancreas cells that make up the pancreatic ducts or,
less often, the cells that secrete digestive enzymes. They are also called pancreatic
ductal adenocarcinoma (PDAC). About 95 out of 100 pancreatic cancers are adenocarcinomas.
When people use the term pancreatic cancer, they usually mean this type.
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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). They can be nonfunctioning
(don't make hormones) or functioning (make hormones). 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.