Neuroendocrine tumors (NETs) are neoplasms originating from neuroendocrine cells located throughout the body. They secret various peptides and cause various symptoms (carcinoid syndrome) or not. The incidence of NETs was not well-known till recently when Yao et al. and Hausa et al. published their surveys of NETs using data from the US Surveillance, Epidemiology, and End Results (SEER) program and from the Norwegian Registry of Cancer (NRC). The incidence of NETs in Taiwan by using the Taiwan Cancer Registry (TCR) data was increased from 0.3 to 1.51 per 100,000 from 1996 to 2008. The increased incidence for NET worldwide probably was partially due to the awareness and improvement of diagnostic technology. Compared with the incidence in western countries, the incidence of NET is much lower in Taiwan. And the incidence of NETs in Asian Pacific Islanders was also lower than the whites and blacks in US. Gastroenteral-pancreatic NETs (GEP-NETs), accounting for half to two thirds of all NETs, is the most common site of NETs. As the progress in the understanding of pathophysiology for GEP-NET, there are two novel targeted agents shown to be effective for the treatment of GEP-NET. Meanwhile, response to mTOR inhibitor was better for Asian than Caucasian in the phase III study using everolimus for advanced pancreatic NETs. These information suggests that there is racial difference for either genetic or environmental risk factors and these factors result in different incidence and/or clinical outcome. Currently, there is limited data for thorough epidemiologic study in Taiwan. The aim of this study is to collect clinical information for GEP-NET, and survey the prognostic factors for GEP-NET in Taiwan. the investigators suppose that this epidemiologic study would provide a database potentially to improve the diagnosis, and treatment of GEP-NET. This study plans to include 600 GEP-NET patients. NET patients diagnosed after 2011.1.1 is included in this study.

Furthermore, the investigators will provide the check of immunohistochemical staining for the tumor tissue of GEP-NET patients, including the functioning status (insulinoma, glucagonoma, gastrinoma, VIPoma) and the degree of differentiation, the expression of SSTR2 or SSTR5 and the check of possible primary site for unknown primary NET patients. This examination will provide more accurate diagnosis for the patients and further treatment suggestion for the patients.

2.0 OBJECTIVES

2.1 To establish the database for GEP-NET by register the clinical presentation, diagnosis, stages, treatment and clinical outcome of GEP-NET patients.

2.2 To analyze the risk and prognostic factors of GEP-NET patients. 2.3 To make a treatment consensus for GEP-NETs

3.0 PATIENT POPULATION There are approximately 500 patients estimated to meet the inclusion criteria from 10 hospitals in Taiwan. This recruitment estimate may vary and will be flexible since no formal sample size is required.

3.1 Inclusion Criteria: 3.1.1 histologically proven GEP-NET patients, according to the WHO classification in any stage.

3.1.2 Signed informed consent 3.2 Exclusion criteria: 3.2.1 patients of GEP-NET without histological proof

Inclusion Criteria:

• Histologically proven GEP-NET patients, according to the WHO classification in any stage.
• Signed informed consent

Exclusion Criteria:

• Patients of GEP-NET without histological proof

2.1 To establish the database for GEP-NET by register the clinical presentation, diagnosis, stages, treatment and clinical outcome of GEP-NET patients.

2.2 To analyze the risk and prognostic factors of GEP-NET patients. 2.3 To make a treatment consensus for GEP-NETs