How Is Pancreatic Cancer Classified?

How Is Pancreatic Cancer Classified?

Pancreatic cancer is categorized depending on whether it affects the exocrine or endocrine functions of the pancreas. There is an important distinction between the two broad types of pancreatic cancer because they have different risk factors, causes, symptoms, diagnostic tests, treatments, and prognoses.

Tumors that affect the exocrine functions are the most common type of pancreatic cancer. Sometimes these tumors or cysts are benign, called cystadenomas. However, it is more likely to find malignant tumors called adenocarcinomas, which account for 95% of exocrine pancreatic cancers. Adenocarcinomas typically start in gland cells in the ducts of the pancreas, but they can also arise from pancreatic enzyme cells (acinar cell carcinoma).

Other types of pancreatic cancers that are associated with exocrine functions include adenosquamous carcinomas, squamous cell carcinomas, and giant cell carcinomas, named for their appearances underneath a microscope. There is also a disease called ampullary cancer (carcinoma of the ampulla of Vater) that starts where the bile duct and pancreatic duct meet the duodenum of the small intestine.

Tumors that affect the endocrine functions of the pancreas are called neuroendocrine or islet cell tumors, but these are fairly uncommon. These tumors are named for the type of hormone-producing cell that is initially affected. For example: insulinomas (insulin), glucagonomas (glucagon), gastrinomas (gastrin), somatostatinomas (somatostatin), and VIPomas (vasoactive intestinal peptide or VIP). Functioning islet cell tumors still make hormones, while non-functioning ones do not. Most of these tumors are benign, but non-functioning tumors are more likely to be malignant, islet cell carcinomas.