By Amanda Gardner
MONDAY, Feb. 8 (HealthDay News) -- People who down two or more soft drinks a week may have double the risk of developing deadly pancreatic cancer, compared to non-soda drinkers, new research suggests.
But the overall number of people developing the malignancy remains low, with the U.S. National Cancer Institute (NCI) estimating 42,470 new cases last year.
"Soft drinks are linked with a higher risk of pancreatic cancer," said Noel Mueller, lead author of a study appearing in the February issue of Cancer Epidemiology, Biomarkers & Prevention. "We can't speculate too much on the mechanism because this is an observational study, but the increased risk may be working through effects of the hormone insulin."
Still, the report should not cause undue alarm, some say.
"The study was well designed but smaller than some previous studies that did not find a link between sugar-sweetened soft drinks and pancreatic cancer," noted Eric Jacobs, strategic director of pharmacoepidemiology at the American Cancer Society. "Direct evidence linking sugar-sweetened soft drinks to pancreatic cancer remains limited."
And adult soda drinkers may also engage in other lifestyle habits, such as smoking, which could contribute to the elevated risk.
"It's an interesting finding but if you look at the people who had the high soft drink intake, they also had other issues that may also predispose you to pancreatic cancer," said Dr. Colin D. Weekes, assistant professor of medicine at the University of Colorado Denver. "It's hard to make any true associations from this. "We could argue that smoking could be the issue here and not the soda intake."
Although the study didn't differentiate between regular and diet soda, it was conducted in Singapore, where most soda consumed is regular, Mueller said.
The study was a collaboration between the University of Minnesota and National University of Singapore. Mueller, formerly at Minnesota, has since joined Georgetown University Medical Center in Washington, DC, as a research associate.
The analysis involved more than 60,000 middle-aged or older Chinese Singaporeans. Researchers calculated how much juice and soda the participants drank on average and followed them for 14 years to see how many developed cancer of the pancreas.
Those who drank two or more sodas a week were 87 percent more likely to develop this kind of tumor than individuals who didn't consume any soda.
Researchers found no link between juice consumption and cancer risk, perhaps because fruit juice has less effect than sugary sodas on glucose and insulin levels, the authors noted.
Previous research in U.S. and European populations has suggested an association between sweetened sodas and juices and pancreatic cancer. This is the first study to examine the association in an Asian population, although the authors feel the findings can be extrapolated to Western nations.
"We believe that because Singaporean adults have a lot of the same mannerisms as Western countries, which is a tendency to eat fast food and also go shopping, one could say that these findings may be generalizable to other Western countries," said Mueller. "Genetically they are very different from Caucasians, however their lifestyle is similar to Western countries."
The findings are biologically plausible.
Type 2 diabetes, a disorder of blood sugar levels and insulin under-activity, has also tentatively been linked to pancreatic cancer.
The researchers speculate that elevated blood sugar levels associated with soda-drinking and the associated increase in insulin levels prompt pancreatic cells to divide abnormally.
"Drinking sugar-sweetened soft drinks has been linked to weight gain, obesity and diabetes. Both obesity and diabetes are associated with higher risk of pancreatic cancer, one of the leading causes of cancer death in the United States," Jacobs said.
The soft drink industry disputed the findings, however.
"The [study] authors are skipping several steps in trying to connect soft drinks with pancreatic cancer, including an allegation regarding an increase in insulin production," Richard Adamson, a consultant to the American Beverage Association and former scientific director of the NCI, said in a statement.