Pancreatic Cancer: Stages and Outcomes
The pancreas is a vital organ of the digestive and endocrine system located behind the stomach. It produces insulin, a hormone responsible for glucose metabolism.
Pancreatic cancer is a life-threatening type of cancer that occurs when the DNA of cells within the pancreas becomes damaged, and tumor forms.
Several debilitating symptoms are associated with pancreatic cancer, but it often goes without diagnosis until later stages of the disease, where cancer has metastasized, and surgical removal is no longer possible.
There are two major types of pancreatic cancer, which are named for the cells in which they originate:
Exocrine Pancreatic Cancer
Most exocrine pancreatic cancer begins in the epithelium of the pancreatic ducts that carry digestive enzymes from the pancreas to other organs. The most commonly diagnosed exocrine cell cancer is pancreatic ductal adenocarcinoma (PDAC), representing approximately 85% of cases.
Common symptoms of PDAC include non-specific symptoms like:
- Abdominal pain and swelling
- Jaundice (yellowing of the skin and eyes)
- Intestinal bleeding
Acinar cell carcinoma (ACC) is the second-most common type of exocrine cell cancer. ACC begins in the cells that produce digestive enzymes of the pancreas and represents approximately 2% of cases of pancreatic in adults and roughly 15% in children.
Although jaundice is uncommon, ACC may cause many of the same symptoms as PDAC, such as nausea, fatigue, and pain.
The 5-year survival rate for exocrine pancreatic cancer is startlingly low. 34% of local non-invasive cases, 12% of regional invasive cases, 3% of distant metastatic cases, and 9% across all stages will survive exocrine pancreatic cancer for 5 years post-treatment.
Endocrine Pancreatic Cancer
Endocrine pancreatic cancer presents as pancreatic neuroendocrine tumors (PNETs) or islet cell tumors, denoting the specific type of cells they grow from. This rare form of pancreatic cancer may be categorized as functional and non-functional depending on whether or not the growth secretes hormones.
Functional PNET symptoms and classifications vary depending on the type of hormones they secrete:
- Gastrinoma causes acid reflux, abdominal pain, diarrhea, weight loss, and fatty stool.
- Glucagonoma causes high blood sugar, severe irritation of the skin, sores of the mouth, anemia, and weight loss.
- Insulinoma causes low blood sugar, shakiness, and confusion.
- Somatostatinoma causes the suppression of a variety of hormones resulting in non-specific symptoms, including diabetes, weight loss, gall stones, fatty stool, diarrhea, nausea, and vomiting.
- Vasoactive intestinal peptide releasing tumors (VIPoma) cause diarrhea, muscle weakness, nausea, and fatigue.
Pancreatic Cancer Staging
Pancreatic cancers stage from 0 to 4 based on how far cancer has grown and how difficult it is to treat. In earlier stages, pancreatic cancer is easier to treat because it covers a smaller area. As cancer spreads and becomes more deadly, the lymph nodes may be affected, or cancer may grow outside of the pancreas. Finally, cancer may invade distant sites.
The cancer is only present in the top layers of the pancreatic ducts and has not proliferated deeper. Stage 0 pancreatic cancer has not spread to either the lymph nodes or distant sites.
Stage I, IB
During stage IA, cancer has invaded deeper into the tissue but is confined to the pancreas and may be up to 0.8” (2 cm) across. At stage IB pancreatic cancer, cancer must be at least 0.8” (2 cm) across but no larger than 1.6” (4 cm) across.
Stage IIA, IIB
At stage IIA, the cancerous tissue is still confined to the pancreas but has enlarged beyond a 1.8” (4cm) area and but has not spread to nearby lymph nodes.
Stage IIB indicates that cancer may have enlarged beyond 1.6” (4 cm) across, or it may be spread to no more than 3 lymph nodes.
As pancreatic cancer progresses through stage III, the tumor may continue to grow in size beyond 1.6” (4 cm) and eventually reach the blood vessels outside the pancreas.
In some cases, cancer may be growing outside the pancreas without affecting any lymph nodes, or it may be present at up to and beyond 4 lymph node sites while remaining confined to the pancreas.
In the final stages of pancreatic cancer, cancer has metastasized and is now growing at distant sites like the liver, the abdominal cavity, lungs, or bones. It can be any size, and the lymph nodes may or may not be affected.
At earlier stages when the cancer is still confined to the pancreas or has spread just beyond it, the tumor may be resectable meaning it can be removed entirely.
The suitability for resection is based on the potential for complications from surgery. Metastatic pancreatic cancer is unresectable, as is cancer that has proliferated into the surrounding blood vessels.