There is no single cause of pancreatic cancer, but smoking is the largest preventable risk factor, responsible for an estimated 25% of all cases. At the genetic level, nearly every pancreatic tumor carries a specific mutation in a gene called KRAS, which acts as the initiating event that starts normal pancreatic cells on the path toward cancer. Beyond these two factors, the disease arises from a combination of age, metabolic conditions, family history, diet, and environmental exposures that interact in ways researchers are still working to untangle.
About 67,440 new cases are expected in the United States in 2025, and roughly 1.6% of Americans will be diagnosed at some point in their lifetime. The median age at diagnosis is 71, with nearly 89% of patients diagnosed after age 55.
The Genetic Trigger Behind Nearly Every Case
At the molecular level, pancreatic ductal adenocarcinoma (the most common type, making up about 90% of pancreatic cancers) is driven by mutations in the KRAS gene. Deep sequencing studies have confirmed KRAS mutations in 94% of these tumors, making pancreatic cancer the most KRAS-dependent of all cancers. This mutation is not just present in advanced tumors. It appears in more than 90% of the earliest precancerous lesions in the pancreas, confirming it as the initiating genetic event.
KRAS acts like a stuck “on” switch for cell growth. In a healthy cell, the KRAS protein flips between active and inactive states, signaling the cell to grow only when appropriate. When the gene is mutated, the protein stays locked in its active state, telling the cell to keep dividing regardless of normal controls. Over time, additional mutations accumulate, and the cell progresses from a precancerous lesion to invasive cancer.
This doesn’t mean KRAS mutations alone cause pancreatic cancer. Most people who develop a KRAS mutation in their pancreas will never progress to full-blown cancer. The mutation creates vulnerability, and the risk factors described below determine whether that vulnerability becomes disease.
Smoking: The Biggest Preventable Risk Factor
Smoking doubles a person’s risk of developing pancreatic cancer and is thought to cause roughly one in four cases. That makes it, by a wide margin, the single most impactful modifiable risk factor. The risk increases with the number of cigarettes smoked per day and the number of years spent smoking. It also decreases after quitting, though it takes years for the elevated risk to fully fade.
Tobacco smoke contains nitrosamines and other compounds that reach the pancreas through the bloodstream. These chemicals can directly damage DNA in pancreatic cells, potentially triggering or accelerating the KRAS mutations that start the cancer process.
Diabetes and Pancreatic Cancer
The relationship between diabetes and pancreatic cancer runs in both directions, which makes it one of the more confusing risk factors. Long-standing type 2 diabetes is a genuine risk factor for pancreatic cancer. The chronic high blood sugar and insulin resistance that come with diabetes create an environment that promotes cell growth in the pancreas over many years.
But pancreatic cancer can also cause diabetes. A growing tumor disrupts the organ’s ability to produce insulin, leading to a sudden rise in blood sugar. Researchers at the National Cancer Institute have identified three clinical signs that help distinguish cancer-driven diabetes from ordinary type 2 diabetes: the person tends to be older, their blood sugar rises more rapidly than is typical for new diabetes, and they lose weight around the time of diagnosis. That last point is especially telling, since most people with new type 2 diabetes gain weight rather than lose it. Fewer than 1 in 100 cases of new-onset diabetes turn out to be caused by pancreatic cancer, but when all three of these signs appear together, further testing may be warranted.
Chronic Pancreatitis
Chronic inflammation of the pancreas, often caused by heavy alcohol use, creates a sustained environment of tissue damage and repair that raises cancer risk. The connection is well established, but the absolute numbers are smaller than many people expect. Over a 20-year period, only about 5% of people with chronic pancreatitis will develop pancreatic cancer. Still, that’s a meaningful increase over the general population’s 1.6% lifetime risk, and it underscores the role that long-term inflammation plays in feeding the progression from precancerous changes to invasive disease.
Family History and Inherited Genes
About 5% to 10% of pancreatic cancers have a hereditary component. Several inherited gene mutations raise risk, with BRCA1 and BRCA2 being among the best studied. Women carrying a BRCA1 mutation face a lifetime pancreatic cancer risk of roughly 2%, while BRCA2 carriers face about a 3% risk. These numbers are modest on their own but represent a meaningful increase over the baseline, and the risk compounds when combined with other factors like smoking or diabetes.
Other inherited conditions linked to higher risk include Lynch syndrome, familial atypical mole-melanoma syndrome, and hereditary pancreatitis. Having two or more first-degree relatives with pancreatic cancer raises risk substantially, even when no specific gene mutation has been identified.
Diet, Obesity, and Processed Meat
Carrying excess weight is consistently linked to higher pancreatic cancer risk. The mechanisms likely involve chronic low-grade inflammation and elevated insulin levels that come with obesity, both of which can promote abnormal cell growth in the pancreas.
Diet plays a role as well. A meta-analysis published in the British Journal of Cancer found that eating an additional 50 grams of processed meat per day (roughly one serving, the equivalent of a couple of sausage links or a few slices of deli meat) was associated with a 19% increase in pancreatic cancer risk. The link with unprocessed red meat is weaker and less consistent. Diets high in fruits, vegetables, and whole grains appear to be modestly protective, though no single food has been shown to dramatically reduce risk.
Occupational and Chemical Exposures
Certain workplace exposures have been linked to pancreatic cancer, though many of these associations are harder to pin down than lifestyle factors. The strongest and most consistent evidence points to two categories of industrial chemicals: chlorinated hydrocarbons (solvents used in degreasing, dry cleaning, and manufacturing) and polycyclic aromatic hydrocarbons, or PAHs (produced by burning coal, oil, gas, and other organic materials).
Workers exposed to chlorinated hydrocarbon solvents showed up to a fourfold increase in risk for pancreatic ductal adenocarcinoma in some studies. Exposure to certain pesticides, particularly organochlorines like DDT and its breakdown products, has also been associated with elevated risk. Metals such as nickel, chromium, and cadmium round out the list of occupational concerns, with nickel-exposed workers showing roughly 1.9 times the expected rate of pancreatic cancer. People who work in metalworking, chemical manufacturing, pest control, or industries involving heavy solvent use may carry higher cumulative exposure.
Age, Race, and Sex
Age is one of the strongest non-modifiable risk factors. Pancreatic cancer is rare before 50, with only about 8% of cases diagnosed in that age group. Risk climbs steeply after 55, and most diagnoses occur in people in their late 60s and 70s.
Racial disparities are significant. Black Americans have higher incidence and mortality rates from pancreatic cancer compared to white Americans. The reasons are likely a combination of genetic differences, higher rates of contributing conditions like diabetes and obesity, differences in healthcare access, and possibly greater exposure to environmental risk factors. Men are also slightly more likely to develop the disease than women, though the gap has narrowed over time as smoking rates have shifted.
How These Risks Add Up
Pancreatic cancer almost always begins with a KRAS mutation, but that mutation alone isn’t enough. What pushes a precancerous cell toward full malignancy is the accumulation of additional genetic damage and a tissue environment that favors tumor growth. Smoking, chronic inflammation from pancreatitis, metabolic stress from obesity and diabetes, chemical exposures, and inherited genetic vulnerabilities all contribute to that environment in overlapping ways.
For most people, the most impactful steps are the ones that address the biggest modifiable risks: not smoking (or quitting), maintaining a healthy weight, limiting processed meat, and managing diabetes effectively. None of these eliminate risk entirely, but together they address the factors behind the largest share of preventable cases.