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What is pancreatic neuroendocrine tumor?
The pancreas has two jobs: it makes digestive juices and it makes hormones. Pancreatic neuroendocrine tumors (pNETs, sometimes called islet cell tumors) start in the hormone-making cells and behave very differently from ordinary pancreatic (exocrine) cancer — they usually grow more slowly and have a much better outlook. Some release excess hormones that cause symptoms (functional tumors, like insulinomas or gastrinomas); most make no hormones and are found as a mass or after they spread, often to the liver. Because these cells carry docking sites called somatostatin receptors, they can be both imaged and treated with receptor-targeted radioactive drugs.
The main types
Doctors group pancreatic neuroendocrine tumor by where it starts and how it behaves:
| Type | What it means, simply |
|---|---|
| Non-functional pNET | Makes no active hormone; most common. Found as a mass or after spread, often discovered late because symptoms are vague. |
| Insulinoma | Makes too much insulin, causing low blood sugar; usually small and benign, and cured by surgery. |
| Gastrinoma | Makes gastrin, driving severe stomach ulcers (Zollinger-Ellison syndrome). |
| Glucagonoma / VIPoma / others | Rarer functional tumors that release other hormones, each causing a distinct set of symptoms. |
Staging, in plain terms
pNETs are staged by tumor size and spread (TNM), but grade is just as important. Grade is based on how fast the cells divide, measured by the Ki-67 marker, and separates slow (G1) from faster (G2) and aggressive (G3) tumors.
| TNM + grade (Ki-67) | What it generally means |
|---|---|
| Grade 1 (Ki-67 under 3%) | Slow-growing. Small ones may simply be watched; larger ones are removed surgically. |
| Grade 2 (Ki-67 3-20%) | Intermediate pace. More likely to need surgery plus medicine if it has spread. |
| Grade 3 (Ki-67 over 20%) | Fast-growing. Treated more like an aggressive cancer, often with chemotherapy. |
| Stage I-IV (extent) | From a small tumor confined to the pancreas (I) to spread to lymph nodes or distant organs like the liver (IV). Even stage IV pNETs can be controlled for years. |
The standard of care
Pancreatic Neuroendocrine Tumor is almost always treated by a team that may include a surgeon, a medical oncologist, and a radiation oncologist, combining therapies for the best result. The usual building blocks are:
Surgery
Removing the tumor is the main cure for localized disease — from scooping out a small insulinoma to a formal pancreas operation for larger tumors.
Somatostatin analogs
Monthly injections (octreotide or lanreotide) that slow tumor growth and calm hormone symptoms; often the first treatment for tumors that have spread.
PRRT and targeted/chemo drugs
For progressing tumors: peptide receptor radionuclide therapy (Lutetium-177 DOTATATE) delivers radiation from the inside, plus options like everolimus, sunitinib, or chemotherapy (capecitabine + temozolomide).
How radiation treatment works
Most radiation for these tumors is given as PRRT — a targeted radioactive medicine. A molecule that mimics the hormone somatostatin carries a radioactive atom (Lutetium-177) directly to the tumor's docking sites, where it releases short-range radiation that breaks the cancer cells' DNA. Because the drug seeks out tumor cells specifically, it can treat deposits all over the body at once with relatively mild side effects. A scan with a similar tracer (DOTATATE PET) first confirms the tumor will 'light up' and respond. External-beam radiation, when used, is reserved for relieving symptoms at a specific spot.
The main ways radiation is delivered for pancreatic neuroendocrine tumor:
PRRT — Lutetium-177 DOTATATE
A somatostatin look-alike is tagged with a radioactive atom, given through an IV, and homes in on the tumor's receptors — delivering radiation directly to deposits throughout the body while sparing healthy tissue. This is 'radiation from within.'
Liver-directed therapy
When the tumor spreads mainly to the liver, treatments aimed at the liver — bland or radioactive bead embolization, ablation, or surgery — control disease and symptoms.
External-beam radiation (selective)
Used for symptom relief, such as a painful bone deposit or a spot pressing on a nerve; not a primary treatment for the pancreas tumor itself.
Latest studies shaping care
Care keeps improving — often toward getting the same excellent results with less burden on patients. A few developments:
NETTER-2 (first-line PRRT): Phase III trial showed Lutetium-177 DOTATATE plus octreotide markedly improved progression-free survival versus high-dose octreotide alone as an initial treatment for higher-grade (G2/G3) advanced GEP-NETs.[1]
ASCO GI 2024 / NETTER-2
NETTER-1 foundation: Established PRRT as a standard for advanced, well-differentiated midgut NETs, with durable disease control and quality-of-life benefit — the basis for expanding into pancreatic NETs.[2]
NEJM / NETTER-1
CAPTEM chemotherapy: The capecitabine + temozolomide oral regimen continues to show meaningful response rates in higher-grade pancreatic NETs, offering an effective non-radioactive option.[3]
Clinical trial program (NCT02358356)
Common questions
Is this the same as pancreatic cancer? No. Ordinary pancreatic cancer (adenocarcinoma) comes from the digestive cells and is aggressive. Neuroendocrine tumors come from the hormone cells, usually grow more slowly, and have a much better outlook — even when they have spread.
What is PRRT and is it safe to be around others? PRRT is a targeted radioactive medicine given through an IV that seeks out tumor cells. You'll receive simple precautions for a short time afterward, but it is well tolerated, and the radiation is delivered mainly to the tumor.
My tumor has spread to the liver — is treatment still worthwhile? Yes. These tumors can be controlled for many years with injections, PRRT, targeted pills, and liver-directed therapy, often with a good quality of life.
References
Numbered sources for the studies cited above. Links open the primary publication on PubMed or the publisher’s site.
- ASCO GI 2024 / NETTER-2 (no indexed identifier — see your care team) ↩
- NEJM / NETTER-1 (no indexed identifier — see your care team) ↩
- Clinical trial program (NCT02358356) (no indexed identifier — see your care team) ↩