tailieunhanh - Chapter 089. Pancreatic Cancer

Over 90% of pancreatic cancers are ductal adenocarcinomas of the exocrine pancreas. These tumors occur twice as frequently in the pancreatic head compared to the rest of the organ, and tend to be aggressive, often presenting when locally inoperable or after distal metastases have occurred. Patients with pancreatic cancer have a poor prognosis, with a 5-year survival of only 5%. The discussion of pancreatic cancer here will be limited to ductal adenocarcinomas. | Chapter 089. Pancreatic Cancer Over 90 of pancreatic cancers are ductal adenocarcinomas of the exocrine pancreas. These tumors occur twice as frequently in the pancreatic head compared to the rest of the organ and tend to be aggressive often presenting when locally inoperable or after distal metastases have occurred. Patients with pancreatic cancer have a poor prognosis with a 5-year survival of only 5 . The discussion of pancreatic cancer here will be limited to ductal adenocarcinomas. Other types of pancreatic neoplasms include islet cell tumors and neuroendocrine tumors Chap. 344 . Incidence and Etiology Epidemiology The lifetime risk of being diagnosed with pancreatic cancer in the United States is . In the United States it is estimated that approximately 37 170 people will be diagnosed with pancreatic cancer in 2007. Consistent with its associated poor prognosis 33 370 are expected to die from this disease in the same year making it the fourth leading cause of cancer-related death. The median age of diagnosis of pancreatic cancer is 72 years with the peak incidence of diagnosis between the ages of 65 and 84 it is rarely diagnosed in those below the age of 50. The incidence is slightly higher in men than women and it is also higher in African Americans than in Caucasians. Etiology Cigarette smoking obesity and nonhereditary chronic pancreatitis appear to be risk factors for the development of pancreatic cancer. With smoking the risk seems to increase with the number of cigarettes consumed and decreases with smoking cessation. Less clear and sometimes conflicting associations have been observed for other environmental factors such as diet coffee and alcohol consumption previous partial gastrectomy or cholecystectomy and Helicobacter pylori. An epidemiologic association between diabetes mellitus and pancreatic cancer has also been demonstrated however it is uncertain if diabetes is a precedent of or consequence of pancreatic cancer. Genetic Considerations .