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BACKGROUND

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Periampullary cancers encompass a mixture of cancers but in general are separated into four subtypes: cancer in the head of the pancreas, distal bile duct cancer, true ampullary cancer, and duodenal cancer. These cancers arise in the vicinity of the ampulla of Vater and are differentiated by their histologic origins (pancreatic, distal bile duct, ampulla of Vater, or duodenum). While pancreatic adenocarcinoma makes up the majority of resected periampullary cancers at 62%, ampullary cancer accounts for 19%, distal bile duct cancer 12%, and duodenal cancer 7% of resected periampullary cancers.1 Although preoperative assessment with imaging and biopsy can distinguish one subtype from the other, often times the tumor origin may be undetermined preoperatively. Moreover, duodenal cancer in the periampullary region as well as intestinal-type ampullary cancer behave in a similar fashion, whereas distal bile duct cancer and pancreaticobiliary-type ampullary cancer behave similar to one another. While 56% of small bowel adenocarcinomas arise in the duodenum, small bowel adenocarcinoma only comprises 2% of all gastrointestinal cancers in the United States.2 This chapter focuses on duodenal adenocarcinoma as well as intestinal-type ampullary cancer, as all other duodenal cancers and periampullary cancers are beyond the scope of this chapter.

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EPIDEMIOLOGY

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Small bowel cancer accounts for 3.1% of all intestinal cancers. Of the malignant small intestinal neoplasms, neuroendocrine tumor accounts for 36.5%, adenocarcinoma 30.9%, lymphoma 18.7%, sarcoma and gastrointestinal stromal tumor 10.0%, and miscellaneous and nonspecified 1.1%.3 Although neuroendocrine tumor surpasses adenocarcinoma as the most common cancer of the small intestine, adenocarcinoma is the most common cancer of the duodenum.4

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Small bowel adenocarcinoma is rare. However, based on the Surveillance, Epidemiology, and End Results (SEER) registry, the incidence increased from 0.49 to 0.66 per 100,000 people from 1973 to 2004.3 Duodenal adenocarcinoma accounts for the majority of the small bowel adenocarcinomas (~50%), which is followed by jejunal (~20%) and ileal (~15%) adenocarcinoma. Duodenal adenocarcinoma is more common in men (60%) with a median patient age of 67 years at presentation. The majority of duodenal adenocarcinoma arises in Caucasians.3,4

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Ampullary cancer is quite rare as well, comprising only 0.5% of all gastrointestinal malignancies. From 1973 to 2005, 5,625 cases of ampullary cancer were reported to the SEER registry. During this period of time, the incidence increased from roughly 0.4 to 0.55 per 100,000 persons. Ampullary cancer is more common in men and increases in incidence after the age of 35. A slight predominance for Caucasians is present as well.5

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RISK FACTORS

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Several factors have been implicated in increasing an individual's risk of developing duodenal and ampullary cancer during a lifetime. Although the duodenum accounts for only 8% of the intestinal length, the majority of small bowel adenocarcinomas occur within the duodenum. More specifically, 57% of duodenal adenocarcinomas occur within the second portion of the duodenum in the periampullary ...

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