Pancreatic cancer is primarily classified into two main types: the more common exocrine tumors, which arise in the ducts that carry the pancreas' digestive enzymes, and the rarer neuroendocrine tumors (also known as islet cell tumors), which develop in hormone-producing cells. Within exocrine pancreatic cancer, there are also less common subtypes such as cystic tumors and acinar cell carcinomas.