胰腺癌-Cancer of the Pancreas

What is the pancreas?

The pancreas is in the upper abdomen and lies behind the stomach and intestines (guts). The shape of the pancreas is like a tadpole, and so the pancreas has a 'head', a 'body' and a 'tail'. The head section is nearest to the duodenum (the part of the gut just after the stomach).

The pancreas makes a fluid that contains enzymes (chemicals) that are needed to digest food. The enzymes are made in the pancreatic cells and are passed into tiny ducts (tubes). These ducts join together like branches of a tree to form the main pancreatic duct. This drains the enzyme-rich fluid into the duodenum. The enzymes are in an inactive form in the pancreas (otherwise they would digest the pancreas). They are 'activated' in the duodenum to digest food.

Groups of special cells called 'Islets of Langerhans' are scattered throughout the pancreas. These cells make the hormones insulin and glucagon. The hormones are passed (secreted) directly into the bloodstream to control the blood sugar level.

The bile duct carries bile from the liver and gallbladder. This joins the pancreatic duct just before it opens into the duodenum. Bile also passes into the duodenum and helps to digest food.

What is cancer?

Cancer is a disease of the cells in the body. The body is made up from millions of tiny cells. There are many different types of cell in the body, and there are many different types of cancer which arise from different types of cell. What all types of cancer have in common is that the cancer cells are abnormal and multiply 'out of control'.

A malignant tumour is a 'lump' or 'growth' of tissue made up from cancer cells which continue to multiply. Malignant tumours invade into nearby tissues and organs which can cause damage. Malignant tumours may also spread to other parts of the body. This happens if some cells break off from the first (primary) tumour and are carried in the bloodstream or lymph channels to other parts of the body. These small groups of cells may then multiply to form 'secondary' tumours (metastases) in one or more parts of the body. These secondary tumours may then grow, invade and damage nearby tissues, and spread again.

Some cancers are more serious than others, some are more easily treated than others (particularly if diagnosed at an early stage), some have a better outlook (prognosis) than others.

So, cancer is not just one condition. In each case it is important to know exactly what type of cancer has developed, how large it has become, and whether it has spread. This will enable you to get reliable information on treatment options and outlook. See separate leaflet called 'What are Cancer and Tumours' for further details about cancer in general.

What is cancer of the pancreas?

Cancer of the pancreas is relatively uncommon. It develops in about 1 in 10,000 people each year in the UK. There are several types of pancreatic cancer, but more than 9 in 10 cases are 'ductal adenocarcinomas'.

Ductal adenocarcinoma of the pancreas
This type of cancer develops from a cell which becomes cancerous in the pancreatic duct. This multiplies and a tumour then develops in and around the duct. As the tumour enlarges: 醫(yī)學(xué)全在線(xiàn)www.med126.com

• It can block the bile duct or the main pancreatic duct. This stops the drainage of bile or pancreatic fluid into the duodenum.
• It invades deeper into the pancreas. In time it may pass through the wall of the pancreas and invade nearby organs such as the duodenum, stomach or liver.
• Some cells may break off into the lymph channels or bloodstream. The cancer may then spread to nearby lymph nodes or spread to other areas of the body (metastasise).

Other types of cancer of the pancreas
There are some rare types of cancer which arise from other types of cells within the pancreas. For example, cells in the pancreas that make insulin or glucagon can become cancerous ('insulinomas' and 'glucagonomas'). These behave differently to ductal adenocarcinoma. For example, they may produce too much insulin or glucagon which can cause various symptoms.

The rest of this leaflet only discusses ductal adenocarcinoma of the pancreas.

What causes cancer (adenocarcinoma) of the pancreas?

A cancerous tumour starts from one abnormal cell. The exact reason why a cell becomes cancerous is unclear. It is thought that something damages or alters certain genes in the cell. This makes the cell abnormal and multiply 'out of control'. (See separate leaflet called 'What Causes Cancer' for more details.)

Many people develop cancer of the pancreas for no apparent reason. However, certain risk factors increase the chance that pancreatic cancer may develop. These include:

• Ageing. It is more common in older people. Most cases are in people over 60.
• Genetic factors. Some families have a higher incidence of pancreatic cancer than average.
• Diet is probably a factor. Eating a fatty diet seems to increase the risk.
• Smoking.
• Chronic pancreatitis (persistent inflammation of the pancreas). Most cases of chronic pancreatitis are due to drinking a lot of alcohol. There are some other less common causes.
• Diabetes. But note: diabetes is common and the vast majority of people with diabetes do not develop cancer of the pancreas.

What are the symptoms of cancer of the pancreas?

Symptoms of a blocked bile duct
In about 7 in 10 cases the tumour first develops in the head of the pancreas. A small tumour often causes no symptoms at first. As the tumour grows it tends to block the bile duct. This stops the flow of bile into the duodenum which leads to:

• Jaundice. (Yellow skin caused by bile seeping into the bloodstream due to the blockage.)
• Dark urine - caused by the jaundiced blood being filtered by the kidneys.
• Pale faeces - as the faeces contain no bile which causes their normal brown colour.
• Generalised itch caused by the bile in the bloodstream.

Pain is often not a feature at first. Therefore a 'painless jaundice' that becomes worse is often the first sign of cancer of the pancreas.

Other symptoms
As the cancer grows in the pancreas, further symptoms that may develop include:

• Pain in the upper abdomen. Pain in the middle of the back can also develop if the tumour spreads backwards.
• You may feel generally unwell and lose weight. These symptoms are often the first to develop if the cancer develops in the body or tail of the pancreas (when the bile duct is not blocked).
• You may not digest food very well as the amount of pancreatic fluid will be reduced. This can cause smelly pale faeces, and weight loss.
• Rarely, diabetes develops if nearly all the pancreas is damaged by the tumour.
• Rarely, a tumour can trigger inflammation of the pancreas - 'acute pancreatitis'. This can cause severe abdominal pain.

If the cancer spreads to other parts of the body, various other symptoms can develop.

How is cancer of the pancreas diagnosed and assessed?

Initial assessment
There are many causes of jaundice and of the other symptoms listed above (for example, a blocked gallstone, hepatitis, cancer, etc). Therefore, some initial tests are usually arranged if you develop jaundice or the other symptoms listed above. Typically, these include an ultrasound scan of the abdomen and various blood tests. These initial tests can usually give a good idea if the cause of jaundice is a blockage from the head of the pancreas.

Another test that may be arranged is ERCP (Endoscopic Retrograde Cholangio-pancreatography). ERCP combines the use of endoscopy (a flexible telescope to look inside your gut) and x-rays. An endoscope is a thin, flexible, telescope. It is passed through the mouth, into the oesophagus and down towards the stomach and duodenum. The endoscope contains fibre optic channels which allows light to shine down so the doctor can see inside. Some dye can also be injected from the endoscope into the bile and pancreatic ducts (a 'retrograde' injection). This is done via a plastic tube in a side channel of the endoscope. X-ray pictures are then taken which can show up the dye. This can outline a tumour that is causing a narrowing of these ducts.

Certain treatments can be also be done via the endoscope. For example, a stent can put into a narrowed duct to relieve a blockage (see below). See leaflet called 'ERCP' for details.

To confirm the diagnosis
A biopsy of a suspected tumour can confirm the diagnosis. A biopsy is when a small sample of tissue is removed from a part of the body. The sample is then examined under the microscope to look for abnormal cells. A biopsy can be taken during an ERCP. Sometimes a biopsy is taken by using a long fine needle which is passed through the wall of the abdomen, and guided to a suspected tumour by using an ultrasound scanner or other type of scan. Sometimes a biopsy is taken during a small operation to look into the abdomen (laparoscopy).

However, if surgery is being considered to remove a suspected pancreatic cancer, a biopsy may not be done. This is because there is a risk that taking a biopsy can cause some cancer cells to spread. Information from other tests or scans may be sufficient for a doctor to be confident that the cause of symptoms is a cancer of the pancreas.

Assessing the extent and spread
The above tests may be sufficient to assess the extent of the cancer. In some cases, further tests may be needed to assess if the cancer has spread. For example, a CT scan, MRI scan, or other tests. (There are separate leaflets which describe each of these tests in more detail.) This assessment is called 'staging' of the cancer. The aim of staging is to find out:

• How much the cancer in the pancreas has grown, and whether it has grown to the edge, or through the outer part of the pancreas.
• Whether the cancer has spread to local lymph nodes.
• Whether the cancer has spread to other areas of the body (metastasised).

By finding out the stage of the cancer it helps doctors to advise on the best treatment options. It also gives a reasonable indication of outlook (prognosis). See separate leaflet called 'Cancer Staging and Grading' for details.

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