Tumors Of The Exocrine Pancreas

The classification of tumors is important for understanding tumor histogenesis, for predicting prognosis, for differential diagnosis, and for recommending appropriate therapy. Since 1836, when pancreatic cancer was first described, progress has been made in pancreatic cancer morphology, and a number of classifications have been proposed. All of these classifications are mainly based on morphological characteristics. Some are too detailed to be of practical use while others are more pragmatic. Some of the inherent problems in the previous classifications included difficulties in obtaining an adequate number of pan creatic tumors for examination and insufficient clinical data and follow-up. With the increasing incidence of pancreatic cancer in many parts of the world during the past six decades, and with the availability of more tumors to patho logists, advances have been made in pancreatic tumor studies. Classifications by Cubilla and Fitzgerald and by Kloppel, which are generally similar, mostly considered prominent morphological features and their histogenesis. These pathology-oriented classifications, although complete, were not practical from the standpoint of clinicians concerned with the prognosis of individual tumors.

In Collaboration with Pathologists in 7 Countries

For a long time, approximately since Oberlin and Guerin described the multifocal origin of pancreatic cancers and precancerous pancreatic lesions, no important study dealing with the entire subject of pancreatic cancer has been published in France and probably in the international literature. For some decades the knowl edge acquired 40years or more ago was not improved appreciably, though the fre quency ofthe disease started to increase in occidental countries. This has recently changed, and the progress ofthe medical sciences has spread to the pancreas. Although the surgical or medical prognosis of the most frequent form of pancreatic cancer, exocrine adenocarcinoma, remains very bad, recent studies have shown the multiplicityofits pathological forms, some being less severe so that curative surgery is possible. New experimental models, particularly in the hamster, and the use of carcinogenic drugs allow experimental studies on lesions similar to those in man. Oncologic immunology is still at its beginnings but shows promise for diagnosis and treatment. Though modem techniques of imaging sonography, aspirative cytology, CT scan, endoscopic catheterism, arteriography, and maybe in the future nuclear magnetic resonance - have not yet significantly in fluenced prognosis, they have made the diagnosis easierand more precocious. Yet in a diseasethat diffuses so rapidly to deep lymph nodes, it has not been proved whether early diagnosis can improve prognosis.

The secretions of the exocrine pancreas provide for digestion of a meal into components that are then available for processing and absorption by the intestinal epithelium. Without the exocrine pancreas, malabsorption and malnutrition result. This chapter describes the cellular participants responsible for the secretion of digestive enzymes and fluid that in combination provide a pancreatic secretion that accomplishes the digestive functions of the gland. Key cellular participants, the acinar cell and the duct cell, are responsible for digestive enzyme and fluid secretion, respectively, of the exocrine pancreas. This chapter describes the neurohumoral pathways that mediate the pancreatic response to a meal as well as details of the cellular mechanisms that are necessary for the organ responses, including protein synthesis and transport and ion transports, and the regulation of these responses by intracellular signaling systems. Examples of pancreatic diseases resulting from dysfunction in cellular mechanisms provide emphasis of the importance of the normal physiologic mechanisms.