Types and Where They Begin

A disease with many possible starting points

Neuroendocrine tumors can arise in the gastrointestinal tract, pancreas, or lung, among other sites. The primary site is where a tumor began; a tumor found in the liver may have spread there from another site. Sometimes the primary site remains unknown despite testing. NCI: Cancer staging

• Gastrointestinal tumors can begin in sites including the small intestine, appendix, rectum, or stomach. Their behavior and management vary by site.
• Pancreatic NETs start in hormone-producing cells and are distinct from the more common pancreatic ductal adenocarcinoma.
• Lung neuroendocrine tumors include carcinoid tumors as well as other, different neuroendocrine cancers. Lung classification and grading are not simply interchangeable with digestive-system frameworks.

Names reveal different features

In the digestive system, well-differentiated NET and poorly differentiated NEC are distinct diagnoses. A well-differentiated NET can be high grade; a poorly differentiated NEC is generally high grade. The same treatment approach does not automatically apply to both. NCI: Pancreatic NETs

Stage describes where cancer is present, while grade describes features related to growth. A tumor may be low grade and have spread, or high grade and still be localized. Ask your team which classification system applies to your tumor. NCI: Lung neuroendocrine tumor classification

Functional does not mean more advanced

Some tumors release hormones that cause a recognizable syndrome; these are called functional. Others do not cause a hormone-excess syndrome and are called nonfunctional. Nonfunctional tumors can still grow or spread. Hormone activity, grade, and stage describe different aspects of the disease.

What this means for your care

The tumor site and pathology, extent of disease, symptoms, overall health, and your priorities all matter. Your team may include specialists in oncology, surgery, pathology, imaging, and symptom management. A second opinion can help clarify an unfamiliar diagnosis or complex decision.

• What is my exact diagnosis and primary site?
• Which features distinguish my tumor from other neuroendocrine cancers?
• What remains uncertain, and does it affect our next decision?