[Etiology and carcinogenesis of pancreatic ductal adenocarcinoma]

Pancreatic cancer is currently the major leading cause of cancer-related deaths in the Western countries with an overall 5-year survival rate of less than 3. The key aim of investigation is to identify the cellular population in which some of the earliest molecular events occur, presumably the ultimate target for carcinogenic insult. Advances in pathological classification and genetics have improved our descriptive understanding of this disease. However, important aspects of pancreatic cancer biology remain poorly understood. Factors associated with the increased risk of pancreatic cancer include smoking, chronic pancreatitis, diabetes, prior gastric surgery, and exposure to radiation or chemicals. A number of syndromes have been identified with the increased incidence of pancreatic cancer, including familial atypical multiple-mole melanoma syndrome, hereditary nonpolyposis colorectal cancer, and hereditary pancreatitis, etc. Recently, there have been growing evidences that stem cell biology could provide new insights into the understanding of cancer biology. Three postulates regarding the relationship between stem and tumor cells have been proposed. First, the similarities in the mechanisms that regulate self-renewal of normal stem cells and cancer cells. Second, the possibility that tumor cells might arise from normal stem cells and third, the notion that tumors might contain 'cancer stem cells' - rare cells with indefinite proliferative potential which drive the formation and growth of tumors. New insights for the cancer stem cells and their possible markers in pancreatic cancer have been suggested recently. Further observations of molecular and cellular events in the early stage of pancreatic carcinogenesis may have important implications regarding the cellular lineage responsible for pancreatic ductal metaplasia and neoplasia, and provide further support for the presence of stem cell capabilities within mature pancreatic epithelium.