The short answer
About 95 percent of pancreatic cancers start in exocrine cells, most often as adenocarcinoma. The rest start in neuroendocrine cells and behave very differently, often growing more slowly and needing different treatment.
The pancreas has two main cell types: exocrine cells and neuroendocrine (endocrine) cells.
About 95 percent of pancreatic cancers are exocrine tumors, most often adenocarcinoma.
Neuroendocrine tumors, sometimes called islet cell tumors, make up a small share of pancreatic cancers.
Neuroendocrine tumors often grow more slowly and are treated differently from exocrine cancer.
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The full explanation.
The simple version
The pancreas has two main jobs, and two main kinds of cells. Exocrine cells make digestive enzymes. Endocrine cells, also called neuroendocrine cells, make hormones like insulin. Cancer can start in either kind. The two types behave very differently.
Exocrine pancreatic cancer
Most pancreatic cancers start in exocrine cells. About 95 percent of those are adenocarcinoma. It starts in the cells that line the pancreatic ducts. When people say "pancreatic cancer" without naming a type, they usually mean this one. It tends to grow faster. At later stages it is harder to treat than most neuroendocrine tumors.
Neuroendocrine pancreatic tumors
A smaller share of these cancers start in the hormone-making cells. They are sometimes called islet cell tumors. Another name is pancreatic neuroendocrine tumors, or PNETs. These tumors:
- Often grow more slowly than exocrine pancreatic cancer.
- Can be "functional." That means they make extra hormones that cause symptoms. Too much insulin, for example, can push blood sugar too low.
- Can also be "non-functional." These cause symptoms by their size or spread, not by hormone effects.
- Are staged and treated in their own way. The outlook is sometimes better, though it varies by tumor grade and stage.
In short: exocrine cancer, nearly always adenocarcinoma, is the usual kind. Neuroendocrine tumors are the smaller remainder, and they act very differently.
Why the distinction matters for treatment
These two types come from different cells. They also grow at different rates. So they are staged with different systems and treated in different ways. That includes different chemotherapy drugs. For some neuroendocrine tumors it also includes hormone-blocking therapy. A biopsy and pathology review confirm which type you have. That is one of the first and most important steps after a pancreatic mass is found.
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Words to know
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Common questions
What does exocrine and neuroendocrine mean?
Exocrine cells in the pancreas make enzymes that help digest food. Neuroendocrine cells, also called islet cells, make hormones like insulin. Cancer can start in either type of cell, and the two behave very differently.
Which type is more common?
About 95 percent of pancreatic cancers are exocrine tumors, most often a type called adenocarcinoma. When people say 'pancreatic cancer' without specifying, they usually mean this type.
Are neuroendocrine pancreatic tumors less serious?
Not always, but many neuroendocrine tumors grow more slowly than exocrine pancreatic cancer, and some produce hormones that cause distinct symptoms. Treatment and outlook can differ significantly from exocrine cancer, so the distinction matters.
How do I know which type I have?
A biopsy and pathology review determine the exact cell type. Ask your care team directly whether your cancer is exocrine or neuroendocrine, since this shapes your whole treatment plan.
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Last updated: 2026-08-11Next planned review: 2027-08-03
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How this page was created
Cancer Explained does not originate medical claims. Every page restates guidance already published by the National Cancer Institute, the CDC, the USPSTF and the FDA, in plain language, with the source cited so you can check the original yourself. AI does the translating and organizing; automated checks test claims, citations, clarity and safety before anything publishes. We do not employ clinicians and do not intend to — our work is translation and navigation, not clinical judgment. Nothing here is personal medical advice, and no page can account for your particular situation.
Editorial status: Source checked — This page was written with AI assistance and checked line by line against the sources listed on it. That confirms the sources support what the page says. It is not a medical review, and it does not confirm the page is complete or right for your situation.
Human medical review: not completed. Pages here are not signed off by a clinician before they publish. That is not an oversight we are quietly working around: we restate published guidance and cite it, so the authority belongs to the source rather than to us, and every page names where its claims come from — you can verify us instead of trusting us. Where a volunteer clinician has reviewed a page, their name and credentials appear on it; where no name appears, no clinician has checked it. We are glad to have reviewers and are recruiting them, and we do not hold pages back waiting for one. Use this site to understand your situation and to ask better questions of the people treating you.
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