Drinking two or more sweetened soft drinks a week can have a much higher risk of pancreatic cancer, warn researchers.
People who drank mostly fruit juice instead of sodas did not have the same risk, the study of 60,000 people in Singapore found.
Sugar may be to blame but people who drink sweetened sodas regularly often have other poor health habits, said Mark Pereira of the University of Minnesota, who led the study.
"The high levels of sugar in soft drinks may be increasing the level of insulin in the body, which we think contributes to pancreatic cancer cell growth," Pereira said.
Insulin, which helps the body metabolise sugar, is made in the pancreas.
Writing in the journal Cancer Epidemiology, Biomarkers & Prevention, Pereira and colleagues said they tracked 60,524 men and women for 14 years.
Over that time, 140 of the volunteers developed pancreatic cancer. Those who drank two or more soft drinks a week had an 87pc higher risk of being among those who got pancreatic cancer.
"Singapore is a wealthy country with excellent healthcare. Favourite pastimes are eating and shopping, so the findings should apply to other western countries," he said.
But Susan Mayne of the Yale Cancer Center at Yale University in Connecticut was cautious.
"Although this study found a risk, the finding was based on a relatively small number of cases and it remains unclear whether it is a causal association or not," said Mayne.
"Soft drink consumption in Singapore was associated with several other adverse health behaviours such as smoking and red meat intake, which we can't accurately control for."
Other studies have linked pancreatic cancer to red meat, especially burned or charred meat.
Pancreatic cancer is one of the deadliest forms of cancer, with 230,000 cases globally. In the United States, 37,680 people are diagnosed with pancreatic cancer in a year and 34,290 die of it.
The American Cancer Society says the five-year survival rate for pancreatic cancer patients is about 5pc.
Some researchers believe high sugar intake may fuel some forms of cancer, although the evidence has been contradictory.
One 12-ounce (355 ml) can of non-diet soda contains about 130 calories, almost all of them from sugar, say researchers.