The Pancreas & Cancers of the Pancreas
The pancreas is part of your digestive system.
- pancreatic juice (a fluid containing enzymes which helps to digest food) and
- insulin (a hormone which controls the level of sugar in your blood).
The pancreas lies at the back of the upper abdomen behind the stomach. It is about 15cm long and shaped like a tadpole. The large rounded section on the right hand side of the body is called the head of the pancreas, the middle section is called the body and the narrow part is known as the tail.
The duct of the pancreas meets the bile duct and together they form a channel through which the fluids produced by the pancreas and the bile duct flow out into the duodenum. The bile duct may get blocked when a pancreatic tumour invades it. This causes jaundice (yellowing of the eyes and skin and dark urine).
The pancreas contains two types of glands:
- Exocrine glands – create the enzymes that help digest (break down) foods; and
- Endocrine glands – create the hormones such as insulin and glucagon, which control blood sugars and other functions of the intestine.
Cancers of the Pancreas
In 80-85% of cases, tumours will arise in the head of the pancreas, with the remainder arising in either the body (10%) or tail (5%).
However, rather than its location, a tumour’s type is determined by the kind of cell from which the cancer started.
The most common cancers (95%) start from the cells in the inner lining of the pancreatic ducts and are called “exocrine tumours”. Most of these tumours are called a “Pancreactic Ductal Adenocarcinoma” (PDAC). Rarer exocrine tumours of the pancreas include “Adenosquamous Carcinomas” and undifferentiated carcinomas.
There are a several less common tumours which can also affect the pancreas. These include:
- neuroendocrine tumours (pNETs) – arising from the cells in the pancreas which normally produce hormones such as insulin or glucagon. These tumours may or may not continue to produce hormones as they develop
- a type of lymphoma – a cancer arising from the lymphatic tissue in the pancreas
- pancreatic sarcoma – which develops in the tissue that holds the pancreatic cells together
- various cystic tumours
Cancers can sometimes arise from benign tumours within the pancreas. These most commonly start as cystic tumours, where the benign but abnormal cells make an excessive amount of mucin (a jelly-like substance) which accumulates within the pancreas, creating a cyst. There are two types of mucinous tumour:
- a mucinous cystadenoma
- an intraductal papillary mucinous neoplasm (IPMN) – tumour cells that arise from the ductal lining
Both have the potential to develop cancers within them, but they may be detected by scanning while still in a benign state, when excision is potentially curative.
When tumours arise from tissues close to the pancreas, such as the bile duct (cholangiocarcinoma), Ampulla of Vater, (Ampullary adenocarcinoma), or duodenum (duodenal adenocarcinoma), they may cause symptoms similar to pancreatic cancer. These tumours have different treatments and, importantly, a different prognosis.