About Pancreatic Cancer

Pancreatic cancer begins when cells in the pancreas become abnormal and grow out of control to form a malignant tumour.

What is the pancreas?

The pancreas is a large gland sitting high up in your abdomen. It is about 15 cm long and shaped a bit like a tadpole. It is made up of four parts:

• The head of the pancreas is on the right side of the body and is the widest part.
• The neck of the pancreas sits in front of the important vein that takes blood from the bowel to the liver (the superior mesenteric vein).
• The body of the pancreas sits behind the stomach.
• The tail of the pancreas is the thin end and is on the left side under the ribs and next to the spleen.

The pancreas is made up of two types of cells:

1. Exocrine cells cover 95% of the pancreas and make pancreatic enzymes that aid in food digestion. These cells flow down a tube (pancreatic duct) into the first part of the small bowel, which is called the duodenum.
2. Endocrine cells make up the remaining 5% of the pancreas, and produce hormones such as insulin and glucagon, which help control our body’s blood sugar levels. This part of the pancreas is called the endocrine pancreas.

Cancers developing from these two cell types of the pancreas behave differently and cause different symptoms. As treatment management for each type is very different it is important to know what type of pancreatic tumour you have.

The bile duct is another duct coming down from the gallbladder and liver; it joins the duodenum next to the pancreatic duct, where it meets the bowel. This spot is called ampulla of Vater. This area is important as tumours in the head of the pancreas can cause a blockage of the common bile duct and cause jaundice.

The role of the pancreas in food digestion and insulin

Food digestion involves:

• chewing and mixing food in the mouth
• its movement through the digestive tract (from mouth to small intestine)
• the breakdown of large food molecules into smaller ones. 

Once food has been in the stomach for a couple of hours, it is still only partly digested. From here it will move into the duodenum where the pancreas releases its digestive enzymes down the pancreatic duct. These enzymes help break down food into tiny parts so they can be absorbed into the body through the small bowel. 

The pancreas makes the hormone insulin, which keeps the level of sugar in the blood within an acceptable range (after a meal, glucose levels rise as do insulin levels). This allows the cells in our body to get the right amount of food (not too much). If our blood sugar levels become too high, the pancreas will release more insulin. If they become too low, it will produce and release less. If you don’t make enough insulin, you will develop diabetes (see ‘Symptoms of pancreatic cancer’). Diabetes is a disease in which your body has trouble producing or responding to insulin. This can lead to problems with lowered and elevated blood sugar levels. 

What is cancer?

Cancer is a disease of the body’s basic building blocks known as our cells. Cancer starts when these cells begin to grow out of control. Our body is constantly making new cells to help us grow, replace damaged tissue and heal injuries. Normal cells grow, multiply and die in an organised way. However, sometimes things go wrong, and they may form a lump called a tumour.

A tumour can be benign or malignant. Benign tumours are non-cancerous, which means they stay in one place in the body and do not spread to other parts of the body. Malignant tumours are made up of cancerous cells and they can travel through the bloodstream or lymphatic fluid. This means that the cancer can also spread from the organ in which it first began to other organs in the body. This is called a secondary, invasive cancer or metastasis. 

The place the cancer first develops (either in the tissue or organ) is called the primary cancer site. If the cancer doesn’t spread from this primary site, it is known as localised cancer. A cancer or tumour that spreads to nearby or deeper tissue or invades surrounding tissue can grow its own blood supply. This is called angiogenesis. The cancer may then spread (metastasise) further to other organs in the body. 
Cancer that has spread to another organ keeps the same name as the original cancer. For example, pancreatic cancer that has spread to the liver is still called pancreatic cancer, with liver metastasis/es. 

What is pancreatic cancer?

Pancreatic cancer begins when cells in the pancreas become abnormal and grow out of control to form a tumour. Around 70% of pancreatic cancers are found in the head of the pancreas. 

*This video was made possible by support from the James N. Kirby Foundation.

Types of pancreatic cancer

The different types of pancreatic cancer can be divided into two main categories, based on the type of cell the cancer starts in:

• exocrine pancreatic tumours start in exocrine cells
• pancreatic neuroendocrine tumours (PNETs) start in endocrine cells. 

Pancreatic cancer can start in any part of the pancreas, but about 65% start in the head of the pancreas. 

It is important for your doctor to find out where the cancer starts, as well as the type of cell the cancer started in. This will help them decide on the best treatment for your type of pancreatic cancer.

Exocrine pancreatic tumours

Most pancreatic cancers are exocrine tumours. The most common type of exocrine tumour is called a pancreatic ductal adenocarcinoma. 
Other, rarer types of exocrine tumours include cancer of the acinar cells (usually slower growing) and adenosquamous tumours. 

Pancreatic neuroendocrine tumours (PNETs)

Endocrine cells are found in various parts of the body including in parts of the digestive system (stomach, pancreas, bowel and rectum). They are also found in the lungs, ovaries and sometimes in the testes. The function of these cells depends on where in the body they are. 
Tumours that develop in endocrine cells are called neuroendocrine tumours (NETs). About 50% of all NETs start in the digestive system. The tumour is named depending on where it started. For example, a NET starting in the pancreas is called a pancreatic NET or PNET. 
PNETs are rare and only make up about 5% of pancreatic tumours. They develop in the islet cells of the pancreas, which produce hormones such as insulin and glucagon. Endocrine tumours generally have a better outlook (prognosis) than exocrine adenocarcinomas of the pancreas.

Other rare types

Other rare types of pancreatic cancers include:

• pancreatoblastoma, which happen mainly in children and can be linked to genetic conditions but can sometimes develop in adults
• sarcomas, which happen in the connective tissue that holds the cells in the pancreas together
• lymphomas, which happen in the lymphatic system, which runs through the pancreas
• metastases from another cancer (e.g. cancer of the lung, kidney or skin (melanoma) can spread to the pancreas).

If you have a rare type of pancreatic cancer, speak with your doctor about the best treatment for you, as this booklet is mainly about exocrine pancreatic tumours. 

Cysts or non-cancerous tumours

Neoplasms is another term used to describe an abnormal growth of tissue. Cystic neoplasms are fluid-filled sacs that can grow within the pancreas.

Intraductal papillary mucinous neoplasms (IPMN) are a type of cyst that can grow within the cells of the pancreatic duct.

Neoplasms are generally non-cancerous (benign). However, these types of tumours should be closely monitored by a specialist pancreatic doctor because they can turn into pancreatic cancer over time.