PanNETs are a type of neuroendocrine tumor , representing about one third of gastroenteropancreatic neuroendocrine tumors (GEP-NETs). Many PanNETs are benign , while some are malignant . ... However, morphological imaging alone is not sufficient for a definite diagnosis [14] [16] On biopsy , immunohistochemistry is generally positive for chromogranin and synaptophysin . [17] Genetic testing thereof typically shows altered MEN1 and DAXX / ATRX . [17] Staging [ edit ] The 2010 WHO classification of tumors of the digestive system grades all the neuroendocrine tumors into three categories, based on their degree of cellular differentiation (from well-differentiated "NET G1" through to poorly-differentiated "NET G3"). ... Combinations of several medicines have been used, such as doxorubicin with streptozocin and fluorouracil (5-FU) [12] and capecitabine with temozolomide. [ citation needed ] Although marginally effective in well-differentiated PETs, cisplatin with etoposide has some activity in poorly differentiated neuroendocrine cancers (PDNECs), [12] particularly if the PDNEC has an extremely high Ki-67 score of over 50%. [8] : 30 Several targeted therapy agents have been approved in PanNETs by the FDA based on improved progression-free survival (PFS): everolimus (Afinitor) is labeled for treatment of progressive neuroendocrine tumors of pancreatic origin in patients with unresectable, locally advanced or metastatic disease. [20] [21] The safety and effectiveness of everolimus in carcinoid tumors have not been established. [20] [21] sunitinib (Sutent) is labeled for treatment of progressive, well-differentiated pancreatic neuroendocrine tumors in patients with unresectable locally advanced or metastatic disease. [22] [23] Sutent also has approval from the European Commission for the treatment of 'unresectable or metastatic, well-differentiated pancreatic neuroendocrine tumors with disease progression in adults'. [24] A phase III study of sunitinib treatment in well differentiated pNET that had worsened within the past 12 months (either advanced or metastatic disease) showed that sunitinib treatment improved progression-free survival (11.4 months vs. 5.5 months), overall survival , and the objective response rate (9.3% vs. 0.0%) when compared with placebo. [25] Genetics [ edit ] Pancreatic neuroendocrine tumors may arise in the context of multiple endocrine neoplasia type 1 , Von Hippel–Lindau disease , neurofibromatosis type 1 (NF-1) or tuberose sclerosis (TSC) [26] [27] Analysis of somatic DNA mutations in well-differentiated pancreatic neuroendocrine tumors identified four important findings: [28] [6] as expected, the genes mutated in NETs, MEN1 , ATRX , DAXX , TSC2 , PTEN and PIK3CA , [28] are different from the mutated genes previously found in pancreatic adenocarcinoma . [29] [30] one in six well-differentiated pancreatic NETs have mutations in mTOR pathway genes, such as TSC2 , PTEN and PIK3CA . [28] The sequencing discovery might allow selection of which NETs would benefit from mTOR inhibition such as with everolimus , but this awaits validation in a clinical trial . mutations affecting a new cancer pathway involving ATRX and DAXX genes were found in about 40% of pancreatic NETs. [28] The proteins encoded by ATRX and DAXX participate in chromatin remodeling of telomeres ; [31] these mutations are associated with a telomerase -independent maintenance mechanism termed ALT (alternative lengthening of telomeres) that results in abnormally long telomeric ends of chromosomes . [31] ATRX / DAXX and MEN1 mutations were associated with a better prognosis . [28] References [ edit ] ^ Burns WR, Edil BH (March 2012). ... Cancer Management: A Multidisciplinary Approach 13th edition 2010. ISBN 978-0-615-41824-7 Text is available electronically (but may require free registration) at http://www.cancernetwork.com/cancer-management/pancreatic/article/10165/1802606 ^ Ramage JK, Davies AH, Ardill J, Bax N, Caplin M, Grossman A, et al.
MEN1,
ATRX,
DAXX,
ELK3,
TP53,
EPHB1,
SLC6A2,
CEACAM5,
CEACAM7,
UQCRFS1,
DHDDS,
CHPT1,
RALBP1,
CIB1,
SEMA4D,
RIPK1,
CXCR4,
VEGFA,
TTR,
GNA12,
TSC2,
TFE3,
CDKN1B,
PSG2,
POMC,
MYCN,
CEACAM3,
GRN,
MUC16
