Introductory Remarks
Dongyou Liu in Tumors and Cancers, 2017
A tumor/cancer is usually named for the organs or tissues where it starts (e.g., brain cancer, breast cancer, lung cancer, lymphoma, and skin cancer). Depending on the types of tissue involved, tumors/cancers are grouped into a number of broad categories: (i) carcinoma (involving epithelium), (ii) sarcoma (involving soft tissue), (iii) leukemia (involving blood-forming tissue), (iv) lymphoma (involving lymphocytes), (v) myeloma (involving plasma cells), (vi) melanoma (involving melanocytes), (vii) central nervous system cancers (involving brain or spinal cord), (viii) germ cell tumors (involving cells that give rise to sperm or eggs), (ix) neuroendocrine tumors (involving hormone-releasing cells), and (x) carcinoid tumors (a variant of neuroendocrine tumors found mainly in the intestinal tract).
Pathology of the endocrine pancreas
Demetrius Pertsemlidis, William B. Inabnet III, Michel Gagner in Endocrine Surgery, 2017
PanNETs are relatively rare tumors representing approximately 1%–2% of all pancreatic tumors and overall 7% of all neuroendocrine tumors [2]. According to the U.S. Surveillance, Epidemiology, and End Results (SEER) database, the incidence of neuroendocrine tumors in the United States increased nearly fivefold over the past three decades [9]. The annual incidence of PanNETs was 0.43 per 100,000 people in the United States, increasing greater than twofold since the 1980s [10]. However, data from an autopsy study indicated the prevalence of PanNETs varied between 0.8% and 3%, suggesting that the true occurrence of PanNETs may be underestimated [2, 11]. Despite advanced detecting technology and improved modalities of clinical management, the overall prognosis of PanNETs has not changed significantly over the past few decades [7].
Radiopeptide Targeting for Tumor Therapy: Peptide Receptor Distribution
Marco Chinol, Giovanni Paganelli in Radionuclide Peptide Cancer Therapy, 2016
Numerous human cancers express somatostatin receptors, often in high density (2). The majority of these tumors express preferentially one of the somatostatin receptor subtypes, the sst2 subtype. The sst2 subtype is the best investigated of the somatostatin receptor subtypes. Moreover, the currently available somatostatin analogs, such as octreotide and lanreotide, have a particularly high affinity for the sst2 subtype. As shown in Table 3, the majority of neuroendocrine tumors express somatostatin receptors, with a predominance of sst2, and include pituitary adenomas (in particular GH- or TSH-producing adenomas), gastroenteropancreatic and lung neuroendocrine tumors, pheochromocytomas, and paragangliomas. Also tumors of the nervous system express sst2 receptors, such as medulloblastomas, meningiomas and neuroblastomas. Furthermore, non-neural and non-neuroendocrine tumors also can express sst2 receptors, although in lower incidence or density; those include breast cancer, small cell lung cancer, lymphoma, hepatocellular carcinoma, renal cell carcinoma, and gastric carcinoma. Most of the above mentioned tumors, in particular the neuroendocrine tumors, have been imaged in patients for diagnostic purposes. Moreover, many of these tumors have been selected for peptide receptor radiotherapy using 90Yttrium- or 177Lu -labeled octreotide derivatives.
Metastatic neuroendocrine carcinoma presenting with left lateral rectus enlargement and orbital cellulitis
Published in Baylor University Medical Center Proceedings, 2021
Kevin Garrett Tayon, Vishal Kaila, Deepak Sobti, Ivan Vrcek
Neuroendocrine tumors (NET), previously known as carcinoid tumors, derive from the neuroendocrine system.1 They typically originate from the gastrointestinal or pulmonary systems and have a propensity to metastasize to the orbit, specifically the extraocular muscles.2 A 2020 review of 94 cases of orbital NETs, the largest to date, found that 88 of 94 (94%) of NET orbital tumors were metastatic, with most metastases (52 of 88 cases, 59%) coming from the gastrointestinal system.3 Studies have shown excellent absolute 5-year survival rates for NET orbital metastasis of 70% to 80%,3–5 although patients with disease localized to the orbit at presentation live longer than those with disseminated disease.4 In this article, we describe a patient who presented with periorbital pain, diplopia, and eyelid erythema and was found to have a unilateral NET in her lateral rectus muscle as the initial manifestation of her metastatic small intestine NET.
Efficacy and safety of endoscopic submucosal dissection for gastrointestinal neuroendocrine tumors: a 10-year data analysis of Northern China
Published in Scandinavian Journal of Gastroenterology, 2019
Xin Chen, Bianxia Li, Saiyu Wang, Bo Yang, Lanping Zhu, Shuang Ma, Jingyi Wu, Qijin He, Jingwen Zhao, Zhongqing Zheng, Shu Li, Tao Wang, Li Liang
Neuroendocrine tumors (NETs) are rare neoplasms caused by peripheral neuroendocrine systems, scattering in various organs. In 1808, Merling described a type of epithelial tumor which occurred in the gastrointestinal tract generally, resembling as cancer but less invasion than gastrointestinal cancer. In 1907, the tumor was named as ‘carcinoid’ by Oberndorfer officially [1]. Nowadays, carcinoids have been classified as NETs and the most common type of NETs is gastrointestinal neuroendocrine tumors (GI-NETs), which are a group of tumors secreting neuroamines and peptides caused a variety of clinical symptoms including carcinoid syndrome. An analysis of US population survey showed that the incidence rates of neuroendocrine tumors had increased 6.4-fold from 1.09 per 100,000 individuals in 1973 to 6.98 per 100,000 individuals in 2012, and both the incidence of the stomach and rectum are increasing significantly, with an incidence rate of 15-fold and 9-fold, respectively. Furthermore, these increases are likely attributable to better detection and diagnosis for early-stage tumors in partly [2]. Generally, most of GI-NETs patients have no obvious clinical symptoms, and they are often found coincidentally with gastrointestinal endoscopy examinations [3,4].
The management of refractory carcinoid syndrome: challenges and opportunities ahead
Published in Journal of Medical Economics, 2018
Mauro Cives, Eleonora Pellè, Franco Silvestris
Neuroendocrine tumors (NETs) can secrete serotonin and other vasoactive substances, giving rise to the carcinoid syndrome, a constellation of symptoms characterized by diarrhea, flushing, wheezing, and right-sided valvular heart disease1. Carcinoid syndrome occurs in about one fifth of patients with extrapancreatic NET at diagnosis2, while the exact proportion of patients who will develop this condition during the disease course is currently unknown. The recommended first-line treatment of carcinoid syndrome symptoms involves the use of somatostatin analogs (SSAs), and major improvements in flushing and diarrhea are observed in roughly 75% of patients treated with long-acting octreotide or lanreotide3. No significant difference has been demonstrated between the two SSAs in terms of carcinoid syndrome palliation4. Loss of response to SSAs that occurs over time has been associated with multiple mechanisms including desensitization and/or down-regulation of somatostatin receptors (SSTRs) on the tumor cell surface, acquisition of mutations by SSTR genes, and formation of autoantibodies anti-SSA5,6.