Pancreatic Adenocarcinoma and Other Types of Pancreatic Cancer

Not all pancreatic cancers are the same. Knowing the types of pancreatic cancer can help you make sense of your diagnosis.

The type depends on which cells the cancer starts in. The most common type is pancreatic ductal adenocarcinoma. It makes up about 90 percent of cases.^1-3

The 2 main groups of pancreatic cancer

Your pancreas has 2 main kinds of cells. Exocrine cells make juices that help you digest food. Endocrine cells make hormones, like insulin, that help control blood sugar. Doctors group pancreatic cancers by which of these cells they start in.^1,2

About 95 percent of pancreatic cancers begin in exocrine cells. Cancers that start in endocrine cells are called pancreatic neuroendocrine tumors (NETs). You may also hear them called islet cell tumors. They make up less than 5 percent of pancreatic cancers.^1,3

What is pancreatic adenocarcinoma?

The exocrine glands release digestive juices into tiny tubes called ducts. Most pancreatic adenocarcinomas start in the lining of these ducts. That is why doctors often call it pancreatic ductal adenocarcinoma, or PDAC.^1-3

PDAC is by far the most common type of pancreatic cancer. About 95 percent of cancers in the exocrine pancreas are adenocarcinomas. Other exocrine types are much rarer.^1,2

Gene changes in pancreatic adenocarcinoma

Most gene changes linked to pancreatic cancer happen during a person’s life. They are not passed down in families. Some come from chemicals, like those in tobacco smoke. But often the cause is not known.⁴

One gene stands out in PDAC. About 9 in 10 cases have a change in a gene called KRAS. This gene helps control cell growth. The change helps drive the cancer. Other genes that are often changed include TP53, p16, and SMAD4.^4,5

Growths that can turn into cancer

Some growths in the pancreas are not cancer. But some can become cancer over time. They include:²

• Intraductal papillary mucinous neoplasms (IPMNs) – These make a thick fluid called mucin. They can become cancer if not treated. Some can be watched, but others need surgery.
• Mucinous cystic neoplasms (MCNs) – These almost always occur in women. They are not cancer, but some can turn into cancer if not treated.
• Serous cystic neoplasms (SCNs) – These are almost always benign (not cancer). Most do not need surgery unless they grow large or cause symptoms.
• Solid pseudopapillary neoplasms (SPNs) – These tend to grow slowly. They can spread if not treated, but the outlook is usually very good.

Rarer exocrine types

A small number of exocrine cancers are not adenocarcinomas. These include:^2,3

• Acinar cell carcinoma – This makes up 1 to 2 percent of exocrine cancers. It may cause skin rashes and joint pain.
• Adenosquamous carcinoma – This makes up 1 to 4 percent of exocrine cancers. It tends to be more aggressive.
• Colloid carcinoma – This makes up 1 to 3 percent of exocrine cancers. It grows from an IPMN. It is less likely to spread and has a much better outlook.
• Squamous cell carcinoma – This type is very rare. It is usually found after it has already spread.
• Other rare types – These include signet ring cell and undifferentiated carcinomas.

Pancreatic neuroendocrine tumors

Pancreatic NETs form when hormone-making cells grow too fast. They cause different symptoms than adenocarcinoma. They are also diagnosed and treated differently.^6,7

Functional NETs make large amounts of hormones that cause clear symptoms. They are often found while small. Non-functional NETs do not make enough hormones to cause symptoms. So, they often grow large before they are found. Non-functional NETs are more common.⁷

Functional NETs are named for the hormone they make. They include:^6,7

• Insulinoma – Makes too much insulin, which causes low blood sugar. Most are not cancer.
• Gastrinoma – Makes too much of a hormone that raises stomach acid. This can cause stomach ulcers.
• Glucagonoma – Makes too much glucagon. This can cause diabetes and a skin rash. Most are cancer.
• VIPoma and somatostatinoma – These rarer tumors are often cancer. VIPomas can cause severe diarrhea and dehydration.

Talk to your doctor

Your type of pancreatic cancer shapes your care. Types can cause different symptoms and are treated in different ways. Some, like colloid carcinoma, have a better outlook than others.³

Ask your care team which type of pancreatic cancer you have. You might also ask:

• About your type – Where in the pancreas did it start? Is it adenocarcinoma or another type?
• About testing – Should my tumor be tested for gene changes?
• About next steps – What does my type mean for my treatment options?

You are not alone. Many people facing pancreatic cancer find support in our community.