Pancreatic cancer risk factors

A study published in December 2011 estimated that around 29% of pancreatic cancers in the UK in 2010 were caused by smoking. 75 A British study reported that ex-smokers were 1.4 times more likely to die of pancreatic cancer compared with men who had never smoked. Current smokers of less than 25 cigarettes a day had 1.8 times the risk of death and smokers of 25 or more cigarettes a day were at 3.1 times the risk of never smokers. 2

Prospective studies have reported a positive trend with number of years of smoking among men but not women. 3 Smokers are diagnosed on average 10 years younger than non-smokers. 4 Some studies have reported that it takes10-20 years after cessation for risk to return to the level of a never-smoker,3,5,47,71 but recent results from the European Prospective Investigation into Cancer and Nutrition (EPIC) showed that risk fell to the level of a never-smoker within five years of giving up.50 While the chemical cause is unclear, it is possible that N-nitroso compounds in tobacco are carried to the pancreas in the blood. 6

Regular cigar and/or pipe smokers have a 50% increased risk of pancreatic cancer. 1 There is also evidence that risk increases with the use of snus, 7,39   and it has been estimated that one in five cases of pancreatic cancer in Swedish men are due to this factor.52 

According to EPIC, secondhand smoke exposure at home or at work increases the risk of pancreatic cancer by about 50%, and daily exposure in childhood doubles the risk of pancreatic cancer in later life.50,73 An American study showed that offspring of women who smoke have a 40% increased risk.51However, a Candadian case-control study and the Netherlands cohort study showed no significant risk increase with secondhand smoke exposure.70,71

Chronic pancreatitis (CP), diagnosed in about one in 100,000 people in the UK each year, is a condition where the pancreas is inflamed. It is caused in the majority of cases by alcohol abuse. Risk estimates for pancreatic cancer in people suffering from CP range from 2 to 32. 8-10

People suffering from hereditary pancreatitis, which is characterised by onset before the age of 30 and a family history, have a risk ratio of at least 50, 11,12 and an absolute risk of developing pancreatic cancer by the age of 75 of about 50%. 13

A meta-analysis reported a relative risk of 1.8 for pancreatic cancer in people with type II (non-insulin dependent) diabetes. 14 A nested case-control study has recently reported results supporting this association, showing a statistically significant two-fold risk increase in people with biochemically diagnosed type II diabetes or with the highest fasting blood insulin levels.15

Another meta-analysis showed that people with type I and early-onset diabetes have double the risk of pancreatic cancer.40

Gastric ulcer

A history of gastric ulcer is associated with an increase in pancreatic cancer risk,53 especially for people operated on for their ulcer, where the risk is approximately double that of the general population.54 It has been suggested that the bacteria that populate the stomach post-operatively cause formation of carcinogenic nitrosamines.34

Ulcerative colitis and Crohn disease

A seven-fold risk increase for pancreatic cancer, compared to the general population, has been shown for people who were hospitalised for ulcerative colitis before the age of 25, but a lower than doubling of risk was shown for people hospitalised for ulcerative colitis at a later age.55 A 75% risk increase for pancreatic cancer has been shown for people with a previous diagnosis of Crohn disease.56

Periodontal disease

Two studies have shown between a 50% risk increase and a doubling in risk of pancreatic cancer in people with periodontal disease.57,58

Allergies

A significant reduction in risk has been reported in people with a history of allergies and risk decreases with increasing number of allergies and severity of symptoms.31 The relevant allergies are those affecting the skin, such as eczema or hives and reaction to insect bites, hay fever and respiratory allergies other than asthma.32

Previous cancers

According to a large pooled analysis, people are at higher risk of developing pancreatic cancer within 10 years of a diagnosis of cancers of the pharynx, stomach, gallbladder, larynx, lung, cervix, corpus uteri, bladder, and eye and 10 years or later following a diagnosis of cancers of the stomach, colon, gallbladder, breast, cervix, placenta, corpus uteri, ovary, testis, bladder, kidney, and eye, as well as Hodgkin's and non-Hodgkin's lymphomas.Some of these risk increases are probably due to the shared risk factor of smoking. In other cases, it could be due to a genetic link, or to radiotherapy treatment for the first cancer.59

According to the latest analysis combining the results of 23 published prospective studies, increasing body mass index (BMI) is linked to an increased risk of pancreatic cancer. Risk was shown to increase by 10% for a five-unit increase in BMI. 16 

A study published in December 2011 estimated that around 12% of pancreatic cancers in the UK in 2010 were linked to excess bodyweight.76 

The latest summaries of the published evidence show that occupational physical activity protects against pancreatic cancer, but no effect has been shown in relation to recreational physical activity.21,22

Studies show that people with at least one first-degree relative diagnosed with pancreatic cancer have almost double the risk of someone without a family history.41,42 A 45% risk increase has been shown for people with a first-degree relative diagnosed with prostate cancer.42

Chronic heavy alcohol consumption is a risk factor for pancreatitis, but evidence for an association with pancreatic cancer is limited. Some research suggests an increased risk in heavy drinkers, 27-29,48 but no increased risk for people consuming up to 30g of alcohol a day.30 However, a large nested case-control study showed no risk increase, even at consumption of 60g/day or more.72

A meta-analysis has shown that processed meat may increase risk of pancreatic cancer, showing a 19% increase in risk for every 50g intake (equivalent to a sausage or two rashers of bacon). The study also showed an increase in risk of pancreatic cancer in relation to total red meat intake in men, but not in women. The results showed there was a 29% increase in pancreatic cancer risk for men who ate 120g of red meat compared to those who ate no red meat. This may be because men in the study tended to eat more red meat than women.77 

Studies show no effect of fruit and vegetable intake overall.67-69 

According to the results of a meta-analysis, high dietary folate was linked to a 51% reduced risk, but supplements were not shown to have an effect.45 Since that analysis, results have been conflicting.49,60-61

Some studies have shown an increased risk of pancreatic cancer in relation to saturated or total fat intake.62-64  However, other studies have not shown an association.65-66 

section updated 13/01/12

Use of NSAIDs probably has no effect on risk of pancreatic cancer.46