Pancreatic cancer risks and causes

• A quick guide to what's on this page
• How common pancreatic cancer is
• Smoking
• Diet
• Alcohol

• Body weight and exercise
• Other medical conditions
• Family cancer syndromes and genetic factors
• Allergies
• Statins

We don't really know what causes cancer of the pancreas. About 7,700 people in the UK get pancreatic cancer each year. It is the 11th most common cancer in the UK. About two thirds of all cases (63%) are diagnosed are in people over 70. Pancreatic cancer in people under 40 years old is uncommon.

Cigarettes, cigars and chewing tobacco all increase pancreatic cancer risk. 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.  Up to 1 in 5 pancreatic cancers (20%) may be linked to smoking. A large British study showed that people smoking up to 25 cigarettes a day have roughly double the risk of someone who has never smoked, while people smoking more than 25 cigarettes a day have three times the risk.

You may increase your pancreatic cancer risk if you have very high levels of fat and sugar in your diet. And your risk may also be increased if you eat large amounts of saturated fat in red or processed meats. There is some evidence that people who don't eat many fresh vegetables and fruits are more at risk from pancreatic cancer. This is true for many cancers. Lycopene (found in tomatoes), and vitamin C probably protect against pancreatic cancer. There is general information about cancer and diet in the about cancer section.

A diet high in folate has been shown to reduce the risk of pancreatic cancer, but folate supplements have not been shown to reduce the risk. Folate is found in leafy, green vegetables

There is occasionally talk about coffee drinking being linked to pancreatic cancer, but this has not been confirmed in research studies. Most experts do not think there is a link.

About 7 out of 10 cases of chronic pancreatitis are due to long term heavy drinking. Chronic pancreatitis is a known risk factor for cancer of the pancreas. But chronic pancreatitis that is due to alcohol doesn't increase risk as much as other types of chronic pancreatitis. So if there is a link with alcohol and pancreatic cancer risk, it is only very slight.

Being overweight causes a small increase in the risk of pancreatic cancer.  This could be because overweight or inactive people make more insulin.  Insulin is a hormone made by the pancreas.  Doing little or no physical activity may increase the risk of pancreatic cancer but some studies seem to show that it increases risk while other studies don't show any increase, so we don't really know at the moment.

Risk of pancreatic cancer is increased if you have a history of

• Diabetes
• Chronic pancreatitis
• Pancreatitis that runs in families (hereditary pancreatitis)
• Stomach ulcer

Diabetes

Diabetics may have a slightly increased risk of pancreatic cancer (a slight increase in a small risk is still a small risk). But diabetes is already a pancreatic disease - it is the pancreatic cells that normally make insulin. It is possible that a growing cancer causes some cases of diabetes, rather than the diabetes causing the cancer. Pancreatic cancer specialists believe that anyone over 50 who develops diabetes and has unexplained weight loss should be investigated for other pancreatic disease. 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 possible increased risk, the vast majority of people with diabetes will not get cancer of the pancreas.

Chronic pancreatitis

Having chronic pancreatitis increases risk of cancer, although overall it isn't responsible for a large number of cases. Chronic pancreatitis means having an inflamed pancreas over a long period. It is most often caused by long term drinking of alcohol, although this type of chronic pancreatitis is less likely to increase pancreatic cancer risk than other types of pancreatitis.

Hereditary pancreatitis

This is a rare condition, causing inflammation of the pancreas. It is caused by a faulty gene that can be inherited from one parent. About 4 out of 10 of these people will have cancer of the pancreas before they are 70 years old.

Stomach ulcer

Having a stomach ulcer may increase the risk of pancreatic cancer. This could be due to the types of bacteria that can live in the stomach after an operation for stomach ulcer. They can produce carcinogenic chemicals known as nitrosamines.

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 of pancreatic cancer. But there is not yet a genetic test available for pancreatic cancer.

Pancreatic cancer can be part of a 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 at least one first degree relative diagnosed with pancreatic cancer have almost double the risk of people without pancreatic cancer in their family.  People with two 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 or if there are more than two cases in the family.

You may have an increased risk of pancreatic cancer if you carry the breast cancer gene faults BRCA1 or BRCA2. 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'. That is, 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.

Some research suggests that your risk of pancreatic cancer may be lower if you tend to have allergies. The more allergies you have and the more severe your symptoms, the lower your risk may be. We don't know exactly why this is. Research into other cancers of the digestive system have shown the same thing. It may be because your immune system is better at picking up abnormal cells. Or it may be to do with the effect of allergic reactions on the pancreas.

One study has shown a reduced risk of pancreatic cancer in men taking the anticholesterol drugs, statins.