The Foundation Dedicated to Discovering a Cure for Neuroendocrine Cancer

Caring for Carcinoid Foundation

Neuroendocrine Cancer

In this section you will find comprehensive information on carcinoid cancer, pancreatic neuroendocrine tumors, and pheochromocytoma, including their definitions, symptoms, side effects, diagnoses, and treatments.

Since neuroendocrine tumors represent a heterogeneous group of tumors, the World Health Organization in 2000 updated the classification system for them based upon their clinical pathological criteria (Kloppel, Perren, and Heitz, 2004). 

  • Well-differentiated endocrine tumors, with benign or uncertain behavior.
  • Well-differentiated endocrine carcinomas, with low-grade malignant behavior.
  • Poorly differentiated endocrine carcinomas with high-grade malignant behavior.
  • Endocrine/exocrine carcinomas with characteristics of both endocrine and exocrine tumors.

Carcinoid tumors and pancreatic neuroendocrine tumors fall within the classification of well-differentiated endocrine tumors.  Tumors classified as poorly differentiated endocrine carcinoma or endocrine/exocrine carcinoma with characteristics of both endocrine and exocrine tumors are not covered in the Caring for Carcinoid Foundation’s website. For these types of tumors please contact your physician for more information.

For our purposes, the terms carcinoid tumors and pancreatic neuroendocrine tumors refer to well-differentiated endocrine tumors and the information should not be applied to any tumors not characterized as well-differentiated.


Kloppel, G., Perren, A., and Heitz, P. U. (2004). The gasteroenteropancreatic neuroendocrine cell system and its tumors: the WHO classification. Annals of the New York Academy of Science, 1014, 13-27. Retrieved from:

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