Hereditary associations account for only a small fraction of the
total number of cases of pancreatic cancer. Only 7 to 8% of patients
with pancreatic cancer have one or more family members with pancreatic
cancer. Some other inherited syndromes are associated with an increased
incidence of pancreatic cancer, including familial adenomatous polyposis,
familial atypical multiple mole melanoma and hereditary pancreatitis.
Forty percent of patients with hereditary pancreatitis develop pancreatic
cancer by the age of 70. The risk of developing pancreatic cancer
is approximately 75% if the pattern of inheritance is through the
father. Researchers have identified two gene mutations in families
with hereditary pancreatitis. This discovery has helped to allow
for screening in families with a history of familial pancreatitis.
Environmental or Non-Genetic Factors
Although the causes of pancreatic cancer remain ambiguous, researchers
have identified some risk factors that are associated with pancreatic
cancer; however, these environmental factors do not account for
the majority of cases.
Cigarette Smoking: The most consistent risk factor associated with
pancreatic cancer is cigarette smoking. Cigarette smokers are two
to three times more likely to develop pancreatic cancer than nonsmokers.
Approximately 30% of pancreatic cancers are believed to directly
result from smoking.
Age: Research indicates that the risk of pancreatic cancer increases
with age. The average age at diagnosis is 70. People under 40 rarely
develop pancreatic cancer.
Diet: The results of several clinical studies indicate that individuals
who consume a diet high in fat and low in fruits and vegetables
and dietary folate may be at an increased risk of pancreatic cancer.
Some researchers have reported an association between meat and fish
consumption and the risk of pancreatic cancer. This may be related
to the carcinogenic and mutagenic effects of heterocyclic aromatic
amines present in cooked meat and fish.
Obesity: Research indicates that individuals who are obese are at
an increased risk for developing pancreatic cancer. Researchers
used data from two United States cohort studies to evaluate the
relationship between obesity, physical activity and the risk of
pancreatic cancer. The study involved 46,648 men ages 40 to 75 and
117,041 women ages 30 to 55, with10-20 years of follow-up. The results
indicated that individuals with a higher body mass index (BMI) had
an increased risk of pancreatic cancer compared with individuals
with a lower BMI. Furthermore, moderate activity reduced the risk
of pancreatic cancer, especially among individuals with a high BMI.
Occupational exposure: Some studies suggest that exposure to petroleum
and other chemicals might increase the risk of pancreatic cancer.
Petrochemical workers, hairdressers and rubber workers appear to
be at an increased risk of pancreatic cancer.
Pancreatitis: Chronic pancreatitis refers to a long-term inflammation
of the pancreas. Patients with non-hereditary chronic pancreatitis
appear to have an increased incidence of pancreatic cancer; however,
the majority of individuals with chronic pancreatitis never develop
Diabetes: There is an increased incidence of pancreatic cancer among
patients with diabetes. Individuals with diabetes develop pancreatic
cancer twice as often as those who do not have diabetes. Onset of
diabetes may herald the appearance of pancreatic cancer, particularly
if the diabetes occurs during or beyond age 50. Diabetes is present
in 60-80% of patients with pancreatic cancer and the majority of
patients were diagnosed within 2 years of the cancer. Patients with
diabetes and cancer more often do not have a family history of diabetes.
It appears that a subgroup of patients with late onset diabetes
who have no family history of diabetes may be at an increased risk.
Abnormalities of glucose metabolism in individuals who do not have
diabetes are also associated with an increase in pancreatic cancer