A small intestine neuroendocrine tumor is a carcinoid in the distal small intestine or the proximal large intestine. It is a relatively rare cancer and is diagnosed in approximately 1/100000 people every year. In recent decades the incidence has increased.[1] The prognosis is comparatively good with a median survival of more than 8 years.[2] The disease was named by Siegfried Oberndorfer, a German pathologist, in 1907.[3]
Neuroendocrine tumours are classified as functional or non-functional depending on whether hormone secretion produces clinical symptoms or not. In patients with metastatic small-intestinal NETs (SI-NETs), carcinoid syndrome is common and is characterised by diarrhoea, episodic flushing, bronchospasm, and often carcinoid heart disease leading to right-sided valvular dysfunction. [5] Patients with non-functional SI-NETs are frequently asymptomatic or may present with non-specific symptoms, resulting in metastatic disease at diagnosis in approximately 27–73% of cases. [6][7]
There are often several small and highly fibrotic tumors present in the intestine. The tumors often spread to the mesenteries and the liver.[citation needed]
Cause
Familial clustering of the disease, with several relatives being diagnosed may occur.[8] Relatives of patients have an increased risk of developing the disease.[9] Risk factors associated with an increased incidence of small-intestinal neuroendocrine neoplasms (SI- NENs) include smoking,[10] a possible family history of cancer, and a history of gallbladder disease or cholecystectomy. Each of these factors has been linked to an approximately 1.5-fold higher risk of developing SI-NENs.[11]
Genetics
The tumors often harbour loss of chromosome 18q.[12]Mutations in CDKN1B are present in approximately 8% of cases.[13][14] In terms of transcritpomic analysis, small intestinal neurodendocrine tumours present 4 gene expression sub-clusters named Vesicular (Ves), Immune, Epithelial (Epi) and Mesenchymal (Mes). This last signature correlates with a very poor prognosis for the patient. The infitration of cancer associated fibroblasts is particularly abundant.[15]
Traditionally, the primary tumor has been surgically removed even in the case of metastatic disease, although this was in 2017 shown not to improve survival in asymptomatic patients.[17]
References
↑ Yao, James C.; Hassan, Manal; Phan, Alexandria; Dagohoy, Cecile; Leary, Colleen; Mares, Jeannette E.; Abdalla, Eddie K.; Fleming, Jason B.; Vauthey, Jean-Nicolas (2008-06-20). "One hundred years after "carcinoid": epidemiology of and prognostic factors for neuroendocrine tumors in 35,825 cases in the United States". Journal of Clinical Oncology. 26 (18): 3063–3072. doi:10.1200/JCO.2007.15.4377. ISSN1527-7755. PMID18565894.
↑ Norlén, Olov; Stålberg, Peter; Öberg, Kjell; Eriksson, John; Hedberg, Jakob; Hessman, Ola; Janson, Eva Tiensuu; Hellman, Per; Åkerström, Göran (June 2012). "Long-term results of surgery for small intestinal neuroendocrine tumors at a tertiary referral center". World Journal of Surgery. 36 (6): 1419–1431. doi:10.1007/s00268-011-1296-z. ISSN1432-2323. PMID21984144. S2CID2446655.
↑ Modlin, Irvin M.; Shapiro, Michael D.; Kidd, Mark; Eick, Geeta (February 2007). "Siegfried oberndorfer and the evolution of carcinoid disease". Archives of Surgery. 142 (2): 187–197. doi:10.1001/archsurg.142.2.187. ISSN0004-0010. PMID17309971.
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