University of Auckland professor of surgery John Windsor demystifies the pancreas, one of the largest and busiest glands in the body with a vital role in good health and nutrition.
What is it
The earliest description of the pancreas by anatomists was that it was ‘just a fatty cushion on which the stomach rested’. It is salmon pink and shaped like a tadpole, with a head, neck, body and tail. The head is nestled in the curve of the duodenum (a C-shaped portion of the small intestine) and it is draped over the backbone, as it rises obliquely to where the tail of the pancreas laps onto the spleen under the left lower ribs. Unlike most of the abdominal organs we are more familiar with, such as the stomach or liver, the pancreas sits in the body wall behind the abdominal cavity. This is why pancreatic pain is often felt in the back. It is also draped around very major arteries and veins.
It presents a number of challenges to surgeons because of its relationship to vital structures and being hard to access.
What does it do?
One of the fascinating things about the pancreas is that it is really two organs in one, and nobody has ever explained why this is so. One of the organs, called the exocrine pancreas, is a protein factory, producing more protein for its weight than any other organ in the body, except for the breast at the height of lactation. The proteins are enzymes that help to break down food into bits than can be absorbed. These enzymes are delivered into the duodenum, which is where bile is also delivered into the mixed-up food leaving the stomach. In order to avoid being digested itself, the pancreas is able to deliver these enzymes in an inactive form, which are activated where they are needed. The other organ, called the endocrine pancreas, comprises tight little clusters of cells scattered through the pancreas, not unlike currents in a bun, only smaller. These clusters are called islet cells, which are highly specialised and produce a range of hormones. The most important of these is insulin, which is released into the bloodstream to help control blood-glucose levels. Both enzymes and hormones are released in response to a meal, in a highly sophisticated and controlled manner.
What can go wrong with the pancreas?
There is a wide array of diseases of the pancreas that are relatively common.
Diabetes mellitus occurs when there is an inadequate supply of insulin from the pancreas. People develop high blood-sugar levels and risk long-term complications including kidney failure, leg ulcers and blindness. While some people can control their diabetes with diet and tablets, many require regular insulin injections to maintain normal blood-glucose levels.
Acute pancreatitis is one of the most common digestive system diseases. People develop severe pain across the upper abdomen and, usually, in the back too. Three quarters of the time this disease settles on its own, but in the remainder it can be very severe, requiring intensive care, sometimes major surgery, and it can be fatal. The problem starts with digestive enzymes, activated in the pancreas, causing inflammation and severe tissue damage. The two important causes of acute pancreatitis are gallstones and heavy alcohol consumption. Prevention is better than cure.
Chronic pancreatitis is also on the rise and causes progressive scarring and loss of pancreas function. People end up needing enzyme replacement capsules and insulin. They can suffer severe and debilitating pain, which is sometimes very difficult to treat. It is caused not only by excess alcohol, in susceptible people, but also by smoking and, in rare cases, genetic mutations. The consequences of chronic pancreatitis can be devastating, with nutritional, psychosocial and employment issues and a reduced life expectancy.
Pancreatic cancer There are many types of pancreatic cancer, but the most common one starts in the duct and is the fourth leading cause of death from all cancers. It is likely to be the second most common cancer in a decade or so. It has the reputation of being one of the most challenging cancers, partly because it has often spread by the time it comes to our attention.
A minority of people can be offered potentially curable and very major surgery, and all patients are offered some form of chemotherapy.
There are many other important diseases of the pancreas, including autoimmune pancreatitis, pancreatic neuroendocrine tumours and pancreatic cysts of many varieties. These all present their own challenges in both diagnosis and treatment.
What can we do?
Being aware of the importance of the pancreas is a great start, and much more could be done with education about pancreatic diseases. It has been shown that vegetables and fruit consumption are associated with a reduced risk for pancreatic diseases.
The cessation of tobacco use, reducing heavy alcohol consumption and overcoming obesity are also important preventive strategies for pancreatic diseases.
The good news is that progress is being made to improve the outcomes of people with all of these diseases, and there are active programmes undertaking really valuable research.
Pancreatic diseases are often complex to diagnose and treat and it is important that people obtain the best available advice.