What is Pancreatic Cancer?
Pancreatic cancer is a malignant growth of cells of the pancreas. The pancreas is a leaf shaped gland lying on the back wall of the upper abdomen. The leaf shape is divided into three separate areas; these are the head, body and tail. About 80% of pancreatic cancers occur in the head. The pancreas has two jobs:
- one is to secrete digestive enzymes into the gut to break down food
- the other is to produce insulin and other hormones to control blood sugar levels.
The bulk of the pancreas is made up of digestive enzyme producing cells; this is sometimes called the ‘exocrine’ pancreas. The enzymes travel to the gut through the pancreatic duct which opens into the duodenum, the duodenum is the first part of the small bowel. Digestive enzymes break down food into smaller nutrient molecules which are absorbed by the small bowel into the body. Without these enzymes malabsorption, malnutrition and weight loss develop.
Tiny groups of specialised cells called the ‘islets of Langerhans’ are dotted through the pancreas, they produce hormones. The most important hormone is insulin which is secreted into the blood stream to control blood sugar levels. The islet cells are sometimes called the ‘endocrine’ pancreas. As well as insulin some cells in the islets make other hormones involved in controlling blood sugar levels. If these cells stop working or are removed by surgery the main problem relates to the loss of insulin production – this is called diabetes mellitus. If one of these cells becomes malignant and produces too much hormone this will also cause symptoms, in the case of an insulin producing tumour an ‘insulinoma’ for example frequent hypoglycaemic attacks will occur.
Any one of these cell types in the pancreas can become malignant. Because digestive enzyme producing cells of the exocrine form the bulk of the gland these are the ones that usually become malignant, of these 90% are adenocarcinomas, rarer types include cystic tumours and cancers of the acinar cells.
Endocrine tumours are much rarer, they can be benign or malignant; a benign tumour is called an adenoma and a malignant tumour a carcinoma. These tend to present when they are very small because the excess hormones produced cause symptoms at an early stage they include:
- Insulinoma producing the hormone insulin - only 10% are cancerous
- Gastrinoma producing the hormone gastrin - 50% are cancerous
- Glucagonomas produce the hormone glucagons – most are malignant
Around 7200 people develop pancreatic cancer each year in the UK. It is the fifth leading cause of cancer death in women and the sixth in men. The outcome for people with pancreatic cancer is very poor, at least 80% have advanced disease by the time they are diagnosed and are unable to have curative treatment. Only 10-15% of them will survive a year from diagnosis and the five year survival is very low at 3%. For those with early stage disease where curative treatment is possible the results are poor and disease often recurs after treatment, only 15% of people with early potentially curable disease at diagnosis will be alive 5 years later. Clearly most people with pancreatic cancer could be considered terminally ill when diagnosed and those with early disease also fall into that category as soon as disease recurs after primary treatment. About 7000 people die of the disease each year in the UK.
Amended November 2008