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Risks and causes

Some lifestyle factors and certain medical conditions can increase the risk of pancreatic cancer.

We don’t know what causes most pancreatic cancers. But there are some factors that may increase your risk of developing it.

Having any of these risk factors does not mean that you will definitely develop cancer.

Around 8,800 people in the UK get pancreatic cancer each year. It is the 10th most common cancer, excluding non melanoma skin cancer.

It is more common in older people. Almost half of all new cases are diagnosed in people aged 75 and over. Pancreatic cancer is uncommon in people under 40 years old.
 

Cigarettes, cigars, pipes and chewing tobacco all increase pancreatic cancer risk. A large Cancer Research UK study looking at lifestyle factors found that nearly 1 in 3 pancreatic cancers (about 30%) may be linked to smoking.

Cigarette smoke contains chemicals called nitrosamines. Nitrosamines are carcinogenic. They are found in some foods and drinks as well as in cigarette smoke.

Scientists are not exactly sure why smoking affects pancreatic cancer risk, but they think it may be the nitrosamines. 

Stopping smoking reduces the risk. It takes about 20 years after stopping smoking for the pancreatic cancer risk to fall to the same levels as those who have never smoked.

A meta analysis (this looks at the results of many trials that have tested the same idea, and looks at the results all together) has shown that exposure to second hand smoke does not increase pancreatic cancer risk.

Studies in Scandinavia have given mixed results but chewing snus (a type of smokeless tobacco) could increase the risk of pancreatic cancer.

About 7 out of 10 cases (70%) of chronic pancreatitis are due to long term heavy drinking. Chronic pancreatitis is a known risk factor for cancer of the pancreas. 

Some research suggests there may be a link between heavy drinkers and risk of pancreatic cancer.

The risk is higher in people who drink 3 or more alcoholic drinks a day compared to those who drink less than 1 alcoholic drink a day.

People who have had certain types of cancer are at a higher risk. These include:

  • digestive system cancers
  • pharynx (throat) cancer
  • cancer of the neck of the womb (cervical cancer)
  • lung cancer
  • womb cancer
  • breast cancer
  • ovarian cancer 
  • bladder cancer
  • testicular cancer 
  • kidney cancer

In some people the higher risk may be due to smoking, but in other people it could be due to a genetic link or to radiotherapy treatment for the first cancer.

Having radiotherapy treatment for cancer in the past has been linked to an increased risk of pancreatic cancer. But this risk is balanced by the need to treat the original cancer.

The links between diet and pancreatic cancer are unclear. 

A study showed that pancreatic cancer risk was higher in men who ate 120g red meat a day compared to those who ate no red meat.

Some studies show an increase in risk with large amounts of saturated fat in your diet.

A diet high in folate may reduce the risk of pancreatic cancer, but different studies have shown conflicting results. Folate is found in leafy, green vegetables.

A study has estimated that just over 1 in 10 pancreatic cancers (around 10%) in the UK in 2010 were linked to being overweight.

This increase in risk could be because overweight people make more insulin. Insulin is a hormone made by the pancreas.

The World Cancer Research Fund say that physical activity may protect against pancreatic cancer.

This link may be limited to people who do a lot of activity in their job (occupational activity) rather then recreational activity.

Sometimes pancreatic cancer is found to run in a family. This means there is a fault in a gene somewhere. There may be some genetic link in up to 1 in 10 cases (10%) of pancreatic cancer. 

Pancreatic cancer can be part of a family cancer syndrome, where an inherited faulty gene causes a number of different cancers to develop within the members of one family. There are many different types of family cancer syndromes.

People with 2 or more cases of pancreatic cancer in their family (on the same side), but no recognised gene faults, may have familial pancreatic cancer syndrome. The risk is higher if relatives were diagnosed before the age of 60.

You have an increased risk of pancreatic cancer if you carry the breast cancer gene fault BRCA2. You may have an increased risk with a BRCA1 gene fault, but the evidence is less clear.

There is an increased risk for people with the bowel conditions FAP (familial adenomatous polyposis) and HNPCC (hereditary non polyposis colorectal cancer). And in some families with a tendency to have large numbers of unusual moles (Familial Atypical Multiple Mole Melanoma or FAMMM), which increases melanoma risk.

Other rare syndromes that increase risk of pancreatic cancer are Peutz Jeghers syndrome and ataxia telangiectasia.

These are rare conditions. If one runs in your family, you are likely to know about it already.  Most cases of pancreatic cancer are sporadic.This means they do not run in families. So a genetic test would not help in these cases.

Unless you know that your family has one of the particular gene faults mentioned above, having other types of cancer in the family is very unlikely to mean that you have an increased risk of cancer of the pancreas.

A recent large study showed an increased risk of pancreatic cancer in people with a father, brother or son diagnosed with prostate cancer. But we need more studies before we can be sure about this.

Some research suggests that your risk of pancreatic cancer may be lower if you tend to have certain types of allergies such as eczema. It does not include food allergies or asthma.

It may be because your immune system is better at picking up abnormal cells or to do with the effect of allergic reactions on the pancreas.

Other medical conditions

The risk of pancreatic cancer is increased if you have a history of the following:

Long term inflammation of the pancreas is called chronic pancreatitis. This increases the risk of pancreatic cancer, but isn't responsible for a large number of cases.

Chronic pancreatitis is most often caused by long term drinking of alcohol.

This is a rare condition, causing inflammation of the pancreas. It accounts for about 1 out of 100 cases (1%) of pancreatitis. It is caused by a faulty gene that can be inherited from one parent.

People with hereditary pancreatitis have a 50 times increase in risk of pancreatic cancer compared to the rest of the population.

Having a stomach ulcer is not generally linked to a risk of pancreatic cancer. One study did find double the risk of pancreatic cancer in men with stomach ulcers.

People who have had an operation to remove some or all of their stomach in the last 2 years have an increased risk of pancreatic cancer. This increase may be because the cancers are picked up accidentally as a result of all the tests they have following the surgery.

Bacteria growth following surgery may also play a role. The medicines people take for stomach ulcers are not linked with pancreatic cancer risk.

Helicobacter pylori (H pylori) is a bacteria that causes stomach ulcers, and is a known risk factor. Some studies have shown that infection with H pylori increases the risk of pancreatic cancer.

Millions of people are infected with H pylori and most do not get these types of cancer, and so there must be other factors at work.

People with diabetes have an increased risk of pancreatic cancer. Diabetes is a disease of the pancreatic cells that normally make insulin.

It is possible that a growing cancer actually causes some cases of diabetes, rather than the diabetes causing cancer.

Pancreatic cancer specialists believe that anyone over 50 who develops diabetes and has unexplained weight loss should be investigated.

Most people who develop diabetes late in life are overweight, so diabetes and weight loss together are more unusual.

Remember - diabetes is a common disease. Even with the increased risk, the vast majority of people with diabetes will not develop cancer of the pancreas.

Long term infection of hepatitis B increases the risk of pancreatic cancer. Hepatitis C may also increase the risk, but the evidence for this isn't as clear.

Some research has shown an increased risk of pancreatic cancer in people who have tooth or gum disease. It is not clear why this is the case, though a type of bacteria which causes gum disease may play a role.

Other possible causes

Stories about potential causes are often in the media and it isn’t always clear which ideas are supported by evidence. There might be things you have heard of that we haven’t included here. This is because either there is no evidence about them or it is less clear.

For detailed information on pancreatic cancer risks and causes

Information and help

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