Pancreatic cancer originates in the tissues of your pancreas, an organ located behind your stomach that secretes vital substances to aid digestion and to regulate the metabolism of carbohydrates (or sugars) in your body. One type of cell in the pancreas, referred to as exocrine cells, secretes enzymes (specialized proteins that allow chemical processes to occur) into the small intestine for digestion. The other types of cell in the pancreas are endocrine cells, which secrete hormones (insulin and glucagon) into the bloodstream to aid in the regulation of sugar levels.
The exocrine and endocrine cells of the pancreas form very different tumors/cancers. It’s vital to distinguish between these different cancers as they have different risk factors, diagnostic tests, treatments, and prognoses.
However, as more and more people have diagnostic tests performed, such as imaging studies like MRIs and CT scans, the number of pancreatic growths identified continues to increase. Many of the detected growths are not cancerous, such as serous cystic neoplasm (SCN), mucinous cystic neoplasms (MCN), and intraductal papillary mucinous neoplasms (IPMN). However, MCN and IPMNs should be followed as they have the potential to become cancerous.
Endocrine tumors of the pancreas, also known as neuroendocrine tumors (NET) or islet cell tumors, start from endocrine cells. There are many types of pancreatic NET, and these tumors can be benign or cancerous. However, they are quite rare. Examples of NETs include:
The most common type—and most dangerous form—of pancreatic cancer originates from exocrine cells. Sub-types of exocrine pancreatic cancers include:
- Pancreatic adenocarcinoma – comprises 95% of exocrine pancreatic cancers and originates in gland cells
- Solid pseuopapillary neoplasms (SPNs) – usually slow growing and occur in young women
- Rare subtypes include adenosquamous carcinomas, Signet ring carcinomas, Squamous cell carcinomas, Undifferentiated carcinomas, and Giant cell
Unfortunately, pancreatic cancer often has a poor prognosis, or disease outlook, especially if it is exocrine cancer. The cancer is known to spread quickly and is often not diagnosed until late stages when it has progressed and may be difficult to surgically remove. Most pancreatic cancer result from exocrine cells, which do not make hormones and generally do not cause symptoms, which often times allows the tumor to grow before diagnosis. Other types of pancreatic cancer, such as neuroendocrine cancers like islet cell tumors, may be detected earlier and carry a better prognosis.