Neuroendocrine cancer starts in cells that release hormones into the bloodstream
Neuroendocrine cancer develops in cells that do two jobs at once: they produce hormones (like insulin or serotonin) and they respond to nerve signals. These cells exist throughout your body—in the pancreas, lungs, stomach, intestines, and other organs. When they grow abnormally and form a tumor, it becomes neuroendocrine cancer. The cancer can be slow-growing or aggressive depending on the type and where it starts.
These tumors are sometimes called neuroendocrine tumors (NETs) or carcinoid tumors, though "carcinoid" is an older term. Because these cells make hormones, the cancer can cause symptoms that seem unrelated to cancer—flushing, diarrhea, or low blood sugar—before a tumor is ever found on imaging.
Key Takeaways
- Neuroendocrine cancer grows from hormone-producing cells found throughout the body, most commonly in the pancreas and lungs.
- Some neuroendocrine tumors grow slowly and may not cause symptoms for years, while others are more aggressive and spread quickly.
- Symptoms often relate to excess hormones rather than the tumor itself—flushing, diarrhea, or heart palpitations can be the first sign.
- Diagnosis usually requires imaging (CT or MRI), blood tests to measure hormone levels, and sometimes a biopsy to confirm the tumor type.
- Treatment depends on the tumor's location, size, grade, and whether it has spread, and may include surgery, medication, or other therapies.
Where neuroendocrine cancer most commonly develops
The pancreas and lungs are the two most common sites. Pancreatic neuroendocrine tumors (sometimes called islet cell tumors) can produce insulin, gastrin, or other hormones. Lung neuroendocrine tumors are often found in people who have never smoked and may not cause symptoms until they are large.
Neuroendocrine cancer also occurs in the stomach, small intestine, colon, appendix, and rectum. Less commonly, it develops in the thyroid, adrenal glands, or other organs. The location matters because it affects which hormones are released, what symptoms you experience, and what treatment options are available.
How neuroendocrine cancer behaves differently from other cancers
Many neuroendocrine tumors grow slowly. Some people have a tumor for years without knowing it, and it may be found by chance during imaging for an unrelated reason. This slow growth can make early detection harder because there is no urgent warning sign.
However, not all neuroendocrine cancers are slow. Doctors grade these tumors based on how fast the cells are dividing—low-grade tumors grow slowly, intermediate-grade tumors grow at a moderate pace, and high-grade tumors grow quickly and are more likely to spread. A tumor's grade is one of the most important factors in deciding treatment and predicting outcomes.
The hormone production is another key difference. A tumor in the pancreas might release too much insulin, causing dangerously low blood sugar. A lung tumor might release serotonin and other chemicals, causing flushing and diarrhea. These hormone-related symptoms can be the first clue that something is wrong, sometimes years before the tumor itself is found.
Symptoms that may point to neuroendocrine cancer
Because these tumors produce hormones, symptoms often seem unrelated to cancer. Flushing (sudden redness and warmth in the face and chest), chronic diarrhea, and heart palpitations are common. Some people experience wheezing or shortness of breath. Others have low blood sugar, abdominal pain, or weight loss.
The specific symptoms depend on which hormones the tumor is releasing and where the tumor is located. A pancreatic tumor producing too much insulin causes hypoglycemia (low blood sugar), while a tumor releasing gastrin causes severe ulcers and acid reflux. A lung tumor might cause no symptoms at all until it is large enough to press on nearby structures.
Many of these symptoms are vague and can be caused by other conditions, which is why neuroendocrine cancer is sometimes diagnosed late. If you have persistent symptoms that do not fit a clear diagnosis, mention them to your doctor so they can consider whether testing for neuroendocrine cancer makes sense.
How neuroendocrine cancer is diagnosed
Diagnosis usually starts with blood tests to measure hormone levels and tumor markers. If levels are abnormal, imaging follows—typically a CT scan or MRI to look for a tumor. Some tumors show up on a special scan called a somatostatin receptor scintigraphy (SSTR scan), which highlights neuroendocrine cells.
If imaging finds a suspicious mass, a biopsy may be done to confirm it is neuroendocrine cancer and to determine the grade. The biopsy sample is examined under a microscope to count how many cells are dividing, which tells doctors how aggressive the tumor is. This grade is crucial for planning treatment.
Once cancer is confirmed, additional tests may check whether it has spread to the liver, bones, or other organs. This staging process helps your doctor understand how far the cancer has progressed and what treatment options are most appropriate.
Treatment options for neuroendocrine cancer
Surgery is often the first choice if the tumor is localized and can be removed. Removing the tumor can cure the cancer if it has not spread. For tumors that cannot be surgically removed or have spread, other treatments are used.
Somatostatin analogs are medications that slow tumor growth and reduce hormone production. They are often used for slow-growing tumors and can relieve symptoms like diarrhea and flushing. Chemotherapy may be used for high-grade or aggressive tumors. Targeted therapies and immunotherapies are newer options that work against specific features of neuroendocrine cancer cells.
For tumors that have spread to the liver, treatments like peptide receptor radionuclide therapy (PRRT) deliver radiation directly to neuroendocrine cells throughout the body. The right treatment depends on the tumor's grade, location, size, whether it has spread, and your overall health. Your oncologist will discuss which options are most likely to help in your situation.
Living with a neuroendocrine cancer diagnosis
Because many neuroendocrine tumors grow slowly, some people live for years or decades after diagnosis, especially if the cancer is caught early and is low-grade. Regular follow-up imaging and blood tests monitor whether the tumor is growing or whether treatment is working.
Managing hormone-related symptoms is often part of treatment. Medications can control diarrhea, flushing, or low blood sugar while you are receiving cancer treatment. Support from an oncologist who has experience with neuroendocrine cancer is important because these tumors are less common than other cancers and require specialized knowledge.
Frequently Asked Questions
Is neuroendocrine cancer hereditary?
Most neuroendocrine cancers are not inherited. However, some genetic syndromes—like MEN1 (multiple endocrine neoplasia type 1) and VHL (von Hippel-Lindau syndrome)—increase the risk of developing neuroendocrine tumors. If you have a family history of neuroendocrine cancer or these syndromes, genetic testing may be recommended.
Can neuroendocrine cancer be cured?
If the tumor is caught early and can be completely removed by surgery, cure is possible. For tumors that have spread or cannot be fully removed, treatment focuses on slowing growth and managing symptoms. Many people with neuroendocrine cancer live for years with treatment, especially if the tumor is low-grade.
What is the difference between a neuroendocrine tumor and neuroendocrine cancer?
The terms are often used interchangeably, but technically a neuroendocrine tumor is any growth of these cells, while neuroendocrine cancer refers to a malignant (cancerous) tumor. Not all neuroendocrine tumors are cancerous, and some grow so slowly they may never cause harm. Your pathology report will specify whether the tumor is benign or malignant.
How often do I need follow-up appointments after treatment?
Follow-up schedules vary based on the tumor's grade, stage, and treatment received. Low-grade tumors may need imaging and blood tests every 3 to 6 months initially, then less frequently if stable. High-grade tumors typically require more frequent monitoring. Your oncologist will set a schedule based on your specific situation.
Can neuroendocrine cancer come back after surgery?
Yes, recurrence is possible, especially if the tumor was high-grade or had already spread before surgery. This is why follow-up imaging and blood tests continue after treatment. Catching recurrence early allows treatment to begin sooner, which can improve outcomes.