THE NEUROENDOCRINE SYSTEM: The endocrine system is a communication system where hormones act to regulate physiological events. The nervous system performs the same functions using electrical impulses. The neuroendocrine system is the combination of those two systems, or more specifically, the various interfaces between the two systems. A GEP-NET is a tumor of any such interface.
CATEGORIES: The majority of GEP-NETs fall into two nearly distinct categories:
1. Carcinoids
(approx 2/3 of GEP-NETs) – [Also known as neuroendocrine tumors (NETs)]
2. Pancreatic endocrine tumors (PETs).
(approx 1/3 of GEP-NETs) – [Also known as endocrine pancreatic tumors (EPTs), islet cell tumors, and, most recently, neuroendocrine carcinoma (NEC)]
(approx 1/3 of GEP-NETs) – [Also known as endocrine pancreatic tumors (EPTs), islet cell tumors, and, most recently, neuroendocrine carcinoma (NEC)]
ORIGIN: NECs are assumed to originate from within the pancreas islets of Langerhans – or from endocrine pancreatic precursor cells – though they may originate outside of the pancreas.
NECs are not referred to as 'pancreatic cancer'. The term pancreatic cancer almost always refers to adenopancreatic cancer (aka exocrine pancreatic cancers). Adenopancreatic cancers are not a neuroendocrine cancer.
INCIDENCE: Incidence of NECs is estimated at one new case per 100,000 people per year. The total incidence of GEP-NETs in the United States would be about 9,000 new cases per year.
METASTATIC SITES: The most common metastatic sites are the liver, the lymph nodes, and the bones. Liver metastases are so frequent and so well-fed that for many patients, they dominate the course of the cancer. The terms metastatic and malignant are often used interchangeably
TREATMENT: Surgery is the only therapy that can cure GEP-NETs. However, the typical delay in diagnosis, giving the tumor the opportunity to metastasize, makes most GEP-NETs ineligible for surgery (non-resectable).
There is no established standard therapy for the liver metastasis of pancreatic endocrine tumors. The most common nonsurgical therapy for all GEP-NETs is chemotherapy, although chemotherapy is not particularly long-lasting for NECs.
When chemotherapy fails, the most common therapy, in the United States, is more chemotherapy, with a different set of agents. Some studies have shown that the benefit from one agent is not highly predictive of the benefit from another agent, except that the long-term benefit of any agent is likely to be low.
Source: Information taken from public domain.
