Diagnosis and Management of Gastrointestinal Neuroendocrine Tumors: A Comprehensive Literature Review

Abstract

Neuroendocrine tumors (NETs) are epithelial neoplasms with predominant neuroendocrine differentiation and the ability to synthesize and secrete variable hormones and monoamines. They are relatively rare, accounting for 2% of all malignancy cases in the United States. The most common system affected by NETs is the gastrointestinal tract. Clinical presentation depends on the organ being involved and the hormone being secreted. It can be variable from asymptomatic incidental findings on imaging to intestinal obstruction, or carcinoid syndrome (CS). Several biochemical testings are developed to help with the diagnosis of NETs including 5-hydroxyindoleacetic acid (5-HIAA) and chromogranin A (CgA). Computerized tomography (CT) scans and magnetic resonance imaging (MRI) are the most commonly used modalities to localize the primary tumor and evaluate for metastasis. However, radionuclide imaging using somatostatin receptor-based imaging techniques has improved accuracy to detect smaller neoplasm. Surgical removal is the mainstay of treatment for locoregional tumors. Several medical managements are available for non-respectable NETs which include SSAs, peptide receptor radionuclide therapy (PRRT), and platinum-based chemotherapy agents.

Gastroenteropancreatic neuroendocrine tumor of the accessory papilla of the duodenum: a case report

“…Prior to performing local excision, accurate radiographic evaluations are important for localizing tumors. CT and MRI are the most common modalities used for evaluation of the primary tumor and metastasis [ 15 ]. Moreover, somatostatin receptor scintigraphy has improved accuracy to detect smaller GEP-NETs [ 15 ].…”

“…CT and MRI are the most common modalities used for evaluation of the primary tumor and metastasis [ 15 ]. Moreover, somatostatin receptor scintigraphy has improved accuracy to detect smaller GEP-NETs [ 15 ]. Accordingly, local excision should be performed only in limited cases such as high-risk patients for surgery or patients with no lymph node metastases.…”

Current Perspectives on Small Bowel Tumors: Overview of Prevalence, Clinical Manifestations, and Treatment Approaches

“…Multiple Endocrine Neoplasia Syndrome Type 1 (MEN1): Caused by an autosomal dominant defect in the MEN1 gene, this syndrome significantly predisposes individuals to neuroendocrine tumors (NETs) of the upper GI tract, representing 5-10% of all GI NETs. 12,14 5. Neurofibromatosis Type 1 (NF1): An autosomal dominant defect in the NF1 gene, NF1 increases the risk of developing NET and sarcoma by 2-4 times in affected patients.…”

“…Neurofibromatosis Type 1 (NF1): An autosomal dominant defect in the NF1 gene, NF1 increases the risk of developing NET and sarcoma by 2-4 times in affected patients. 12,14 6. Inflammatory Bowel Disease (Crohn's Disease): An autoimmune disorder causing widespread intestinal inflammation, most commonly in the ileum.…”

“…Furthermore, some patients are prone to have valvular heart disease, which occurs in 50% of patients which is mainly due to a deposit of fibrous tissue at the heart valve. 9,14,17 GISTs often present with various symptoms, including GI bleeding, abdominal pain, palpable masses, and weight loss. The most common presentation is gastrointestinal bleeding, which has been reported in up to 80% of cases, higher than other types of small intestine tumors.…”