Pancreatic cancer classification
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [2]
Types
The many types of pancreatic cancer can be divided into two general groups. The vast majority of cases (about 99%) occur in the part of the pancreas which produces digestive enzymes, known as the exocrine component. There are several sub-types of exocrine pancreatic cancers, but their diagnosis and treatment have much in common. The small minority of cancers that arise in the hormone-producing (endocrine) tissue of the pancreas have different clinical characteristics. Both groups occur mainly (but not exclusively) in people over 40, and are slightly more common in men, but some rare sub-types mainly occur in women or children.[1][2]
Exocrine cancers
The exocrine group is dominated by pancreatic adenocarcinoma (variations of this name may add "invasive" and "ductal"), which is by far the most common type, representing about 85% of all pancreatic cancers. This is despite the fact that the tissue from which it arises - the pancreatic ductal epithelium - represents less than 10% of the pancreas by cell volume.[3] This cancer originates in the ducts that carry secretions (such as enzymes and bicarbonate) away from the pancreas. About 60–70% of adenocarcinomas occur in the 'head' of the pancreas (see diagram, right). The next most common type, acinar cell carcinoma of the pancreas, arises in the clusters of cells that produce these enzymes, and represents 5% of exocrine pancreas cancers. Like the 'functioning' endocrine cancers described below, acinar cell carcinomas may cause over-production of certain molecules, in this case digestive enzymes, which may cause symptoms such as skin rashes and joint pain.
Cystadenocarcinomas account for 1% of pancreatic cancers, and they have a better prognosis than the other exocrine types.[4]
Pancreatoblastoma is a rare form, mostly occurring in childhood, and with a relatively good prognosis. Other exocrine cancers include adenosquamous carcinomas, signet ring cell carcinomas, hepatoid carcinomas, colloid carcinomas, undifferentiated carcinomas, and undifferentiated carcinomas with osteoclast-like giant cells. Solid pseudopapillary tumor is a rare low-grade neoplasm that mainly affects younger women, and generally has a very good prognosis.[5]
Pancreatic mucinous cystic neoplasms are a broad group of pancreas tumors that have varying malignant potential. They are being detected at a greatly increased rate as CT scans become more powerful and common, and discussion continues as how best to assess and treat them, given that many are benign.[6]
Neuroendocrine
The small minority of tumors that arise elsewhere in the pancreas are mainly pancreatic neuroendocrine tumors (PanNETs).[7] Neuroendocrine tumors (NETs) are a diverse group of benign or malignant tumors that arise from the body's neuroendocrine cells, which are responsible for integrating the nervous and endocrine systems. NETs can start in most organs of the body, including the pancreas, where the various malignant types are all considered to be rare. PanNETs are grouped into 'functioning' and 'non-functioning' types, depending on the degree to which they produce hormones. The functioning types secrete hormones such as insulin, gastrin, and glucagon into the bloodstream, often in large quantities, giving rise to serious symptoms such as low blood sugar, but also favoring relatively early detection. The most common functioning PanNETs are insulinomas and gastrinomas, named after the hormones they secrete. The non-functioning types do not secrete hormones in a sufficient quantity to give rise to overt clinical symptoms. For this reason, non-functioning PanNETs are often diagnosed only after the cancer has spread to other parts of the body.[8]
As with other neuroendocrine tumors, the history of the terminology and classification of PanNETs is complex.[7] PanNETs are sometimes called "islet cell cancers",[9] even though it is now known that they do not actually arise from islet cells as previously thought.[8]
References
- ↑ Harris, RE (2013). "Epidemiology of pancreatic cancer". Epidemiology of Chronic Disease. Jones & Bartlett. pp. 181–190. ISBN 978-0-7637-8047-0.
- ↑ Öberg K, Knigge U, Kwekkeboom D, Perren A (October 2012). "Neuroendocrine gastro-entero-pancreatic tumors: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up". Annals of Oncology: Official Journal of the European Society for Medical Oncology / ESMO. 23 Suppl 7: vii124–30. doi:10.1093/annonc/mds295. PMID 22997445. (Table 5 outlines the proposed TNM staging system for PanNETs.)
- ↑ Govindan R (2011). DeVita, Hellman, and Rosenberg's Cancer: Cancer: Principles & Practice of Oncology (9th ed.). Lippincott Williams & Wilkins. Chapter 35: Cancer of the Pancreas: Surgical Management. ISBN 978-1-4511-0545-2. Online edition, with updates to 2014
- ↑ Tobias JS, Hochhauser D (2010). Cancer and its Management (6th ed.). pp. 276–7. ISBN 978-1-1187-1325-9.
- ↑ "Types of Pancreas Tumors". The Sol Goldman Pancreas Cancer Research Center. Johns Hopkins Medicine. 2012. Retrieved 18 November 2014.
- ↑ Farrell JJ, Fernández-del Castillo C (June 2013). "Pancreatic cystic neoplasms: management and unanswered questions". Gastroenterology. 144 (6): 1303–15. doi:10.1053/j.gastro.2013.01.073. PMID 23622140.
- ↑ 7.0 7.1 The PanNET denomination is in line with WHO guidelines for the classification of tumors of the digestive system [1] published in 2010. Historically, PanNETs have also been referred to by a variety of terms, and are still commonly called "pancreatic endocrine tumors". See: Klimstra DS, Modlin IR, Coppola D, Lloyd RV, Suster S (August 2010). "The pathologic classification of neuroendocrine tumors: a review of nomenclature, grading, and staging systems" (PDF). Pancreas. 39 (6): 707–12. doi:10.1097/MPA.0b013e3181ec124e. PMID 20664470.
- ↑ 8.0 8.1 Burns WR, Edil BH (March 2012). "Neuroendocrine pancreatic tumors: guidelines for management and update". Current treatment options in oncology. 13 (1): 24–34. doi:10.1007/s11864-011-0172-2. PMID 22198808.
- ↑ The Medical Subject Headings indexing system refers to "islet cell carcinoma", which is subdivided into gastrinoma, glucagonoma, somatostatinoma and VIPoma. See: 2014 MeSH tree at "Pancreatic Neoplasms [C04.588.322.475]" 16 October 2014