Causes of pancreatic cancer
The exact causes of pancreatic cancer are not known but it is thought that age, smoking, obesity and a family history of pancreatic cancer or other rare genetic conditions increase your risk.
A study published in December 2011 estimated that, in the UK, around 36% of pancreatic cancers in men and 39% in women are linked to lifestyle factors including tobacco smoking and being overweight/obesity (1)
Risk of Contracting Pancreatic Cancer:
The estimated lifetime risk of contracting pancreatic cancer is relatively low at 1 in 73 for men and 1 in 74 for women (2)
|By Age 65 (%)||0.3||0.2|
|Lifetime risk (%)||1.4||1.4|
|Lifetime risk (1in X)||73||74|
Pancreatic Cancer Affects Men & Women Equally:
Ratio of male to female pancreatic cancer incidence, UK 2010* (3)
- All ages: 1.27
- (15-64): 1.38
- (64+): 1.21
Ratio of male to female pancreatic cancer mortality, UK 2010*:
- All ages: 1.27
- (15-64): 1.44
- (64+): 1.20
* European age-standardised rates per 100,000 population.
Age is the biggest risk factor for pancreatic cancer:
Age is the most significant risk factor for pancreatic cancer. The risk is low up until the age of 50 when it increases sharply. The median age of diagnosis is 72. (4)
|Age||% of patients|
Pancreatic cancer can often be missed in younger patients
Although the peak incidence is in the 65-75 year age group, pancreatic cancer can occur from the age of 20 with rates rising significantly from 45 years. (5)
40 per cent of all patients diagnosed in England between 2005 and 2009 were under the age of 69 (6)
Smoking causes nearly 1 in 3 of all pancreatic cancers:
Among the 250 known harmful chemicals in tobacco smoke, at least 69 can cause cancer by damaging the DNA and by changing important genes. This can cause cells to multiply and grow out of control – causing cancerous tumours – see our What is Cancer? section for more information.
Risk of smokers vs. non-smokers
A study in 2006 (8) looked at the risk of contracting pancreatic cancer in smokers versus never smokers in 82 independent studies from 1950 – 2007. They found that smokers have an increased risk of 74% of developing pancreatic cancer compared to those who have never smoked.
A European-wide study in 2012 showed that risk increased by 27 per cent for every five cigarettes smoked per day (9)
Quitting smoking can reduce your risk of contracting pancreatic cancer
Quitting smoking reduces the risk of developing and dying from cancer. However, it takes a number of years after quitting for the risk of cancer to start to decline. This benefit increases the longer a person remains smoke free
Some studies have estimated it can take up to 10 years before the risk begins to decline (10) A European-wide prospective study in 2009 however, showed that risk is reduced to the levels of a non-smoker after just five years of cessation (11)
If you need help to stop smoking, please visit NHS Smoke Free, the NHS Stop Smoking Service.
Effects of passive smoking, cigars and snuff (snus):
The European (EPIC) study showed that passive smoking (or second-hand smoke) either in the home or at work can increase the risk of pancreatic cancer by 50 per cent (12) and that children who are exposed daily to tobacco smoke have double the risk of contracting pancreatic cancer in later life. (13)
Pipe and cigar smoking increases risk by 50 per cent (14) and it is thought that smokeless tobacco (15) and moist snuff (also known as snus) (16) can increase risk.
Alcohol consumption and risk of pancreatic cancer
While there is an association with heavy alcohol consumption and pancreatitis (a benign disease which causes inflammation of the pancreas), there is no confirmed link between alcohol consumption and the risk of pancreatic cancer.
A recent large nested case-control study in 2010 showed no risk increase, even at consumption of 60g/day or more of liquor (spirits), and found no association with beer or wine (17)
In 2007, the World Cancer Research Fund (18) concluded, “the evidence that greater body fatness is a cause of pancreatic cancer is convincing”
Why could obesity increase pancreatic cancer risk?
The fat tissues in overweight people produce more hormones and growth factors than those in people of a healthy weight. High levels of some of these hormones, including insulin which is produced in the pancreas, can increase the risk of certain cancers including pancreatic cancer.
A study in 2011 estimated that around 12 per cent of all pancreatic cancers in the UK are attributable to overweight and obesity. (19)
The Million Women Study (20) found women with a BMI >27.5 had a 20-37 per cent increased risk of pancreatic cancer (compared to those with healthy BMI)(21)
A study in 2008 (22) found that obese women who carry most of their excess weight around the waist rather than hips are “70 per cent more likely to develop pancreatic cancer.”
The latest meta-analysis review on the evidence linking obesity and pancreatic cancer risk conducted by researchers at Imperial College, London and the University of Leeds has confirmed the hypothesis that “increased BMI and abdominal obesity are associated with increased pancreatic cancer risk.” (23)
This study found that there was an increased risk of pancreatic cancer in both men and women who have a BMI of 25 but that risk was more pronounced in those with a BMI of 35 or greater. Risk was shown to increase by 10 per cent for a five-point increase in BMI.
This study also confirmed that carrying your weight around your middle (have a high waist-to-hip ratio) increased risk. A meta-analysis in 2012 (24) found that pancreatic cancer risk increases by 11 % per 10cm waist circumference increase and by 19% per 0.1 unit waist-to-hip increment.
Want to know if you have a healthy BMI? Use the NHS BMI Healthy Weight Calculator
Approx. 1% of diabetics over the age of 50 will be diagnosed with pancreatic cancer within 3 years of “first meeting the criteria for diabetes” (25)
Type-II Diabetes (non-insulin dependent)
Type-II diabetes is widely considered to be associated with pancreatic cancer, but whether diabetes causes pancreatic cancer or the pancreatic cancer causes the diabetes is unclear.
A meta-analysis in 2005 reported a relative risk of 1.8 for pancreatic cancer in people with type II (non-insulin dependent) diabetes and found that individuals in whom diabetes had only recently been diagnosed (less than four years) had a 50 per cent greater risk of pancreatic cancer compared with individuals who had diabetes for greater or equaling five years. (26) A nested case-control study also in 2005 reported results supporting this association. (27)
Type I diabetes and early-onset diabetes
A meta-analysis in 2007 showed that people with type I (insulin dependent), and early-onset diabetes have double the risk of pancreatic cancer. (28)
Diabetes drugs and pancreatic cancer risk
A meta analysis in 2012 showed that metformin, a tablet taken by diabetic patients is associated with a 62 per cent decrease in pancreatic cancer risk, compared with diabetics not receiving this medication, a meta-analysis in 2012 showed. The same study however found that another class of diabetes drug; sulfonylureas did not reduce risk although the results were not consistent between studies (29)
Using data from the General Practice Research Database, a study in 2012 found that there was a decreased risk of pancreatic cancer associated with metformin use but only in women. (30)
The same study also found that diabetes mellitus was associated with an increased risk of pancreatic cancer, but the risk was restricted to those with newly diagnosed diabetes (less than 2 years). This backs up the findings of other scientists that short-term diabetes mellitus is likely caused by pancreatic cancer
There are currently investigations into the merits of using diabetes as a potential biomarker for pancreatic cancer (31) and it has been found that pancreatic cancer induced hyperglycemia (high blood glucose levels) can occur up to 24 months prior to the diagnosis for pancreatic cancer (32)
Pancreatitis and pancreatic cancer risk
It is estimated that one per cent of pancreatic cancer cases are linked to chronic pancreatitis (33)
Chronic pancreatitis is a condition causing chronic inflammation of the pancreas. As compared to acute pancreatitis, it is relatively rare, affecting only 0.1 in 10,000 people in the UK. The majority of cases are linked to heavy alcohol consumption.
Several different studies have shown an increased risk of pancreatic cancer in people suffering from pancreatitis with risk ratios that range from two to more than 20. (34), (35)
A pooled analysis study in 2012 showed that for those who had a diagnosis of pancreatitis at least two years previously, had three times the risk of developing pancreatic cancer. For those in the same group who were under the age of 65 that risk was four times. (36)
Hereditary pancreatitis runs in families and usually occurs at a young age, often before the age of 30. These patients have a risk that is 50-60 times greater than expected. (37) The absolute risk that those suffering hereditary pancreatitis will develop pancreatic cancer by the age of 75 is approximately 50 per cent. (38)
Hereditary Pancreatic Cancer
Sometimes pancreatic cancer is found to run in a family due to faulty genes. It is thought that hereditary pancreatic cancer makes up approx. 5-10% of all cases. There is currently no genetic test available specifically for pancreatic cancer.
People with at least two first-degree relatives (mother, father, brother, sister) diagnosed with pancreatic cancer have almost double the risk of people without pancreatic cancer in their family of contracting the disease. (39)
Click here for more information on hereditary pancreatic cancer
Previous cancers and other conditions
An international multi-centre study was carried out using data from 13 cancer registries in 2006 which found that people are at higher risk of developing pancreatic cancer within 10 years of a diagnosis of cancer of the bladder, cervix, eye, gallbladder, larynx, lung, pharynx stomach and uterus and 10 years or later following a diagnosis of cancers of the breast, bladder, cervix, colon, eye, gallbladder, kidney, ovary, stomach, testis, uterus, as well as Hodgkin’s and non-Hodgkin’s lymphomas. (40)
It is thought that some of these increased risks could be due to smoking, genetic links or to radiotherapy treatment for the first cancer.
Crohn’s disease, gastric ulcers and gum disease
For people with a previous diagnosis for Crohn’s disease, there is a 75 per cent increased risk of contracting pancreatic cancer. (41)
Patients with a gastric ulcer have an 80 per cent increased risk of pancreatic cancer. Those who have had an operation for the gastric ulcer have more than double the risk of the normal population. (42)
A study in 2008 identified that tooth loss and periodontal disease is associated with a 50 per cent risk of pancreatic cancer, (43) while a study in 2010 found a doubling of risk of pancreatic cancer for periodontal disease. (44) The biological mechanism for this association is not currently known.
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