Feb. 8, 2010 -- Drinking as little as two soft drinks a week appears to nearly double the risk of getting pancreatic cancer, according to a new study.
''People who drank two or more soft drinks a week had an 87% increased risk -- or nearly twice the risk -- of pancreatic cancer compared to individuals consuming no soft drinks," says study lead author Noel T. Mueller, MPH, a research associate at the Cancer Control Program at Georgetown University Medical Center, Washington, D.C. The study is published in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research.
The beverage industry took strong exception to the study, calling it flawed and pointing to other research that has found no association between soda consumption and pancreatic cancer.
Cancer of the pancreas was diagnosed in about 42,000 people in the U.S. in 2009, according to American Cancer Society estimates, and about 35,240 deaths from the disease were expected. The pancreas lies behind the stomach. It makes hormones such as insulin to balance sugar in the blood and produces juices with enzymes to help break down fats and protein in foods.
Sodas and Pancreatic Cancer Risk: Study Details
Previous studies have produced mixed conclusions about whether consumption of soft drinks boosts the risk of pancreatic cancer.
So Mueller and his colleagues evaluated 60,524 men and women enrolled in the Singapore Chinese Health Study, begun in 1993, for up to 14 years, looking at their diet and whether they got cancer.
They asked all participants about food intake, including sodas and juices. Mueller says the researchers didn't ask specifically about diet soda consumption, but that most of the soda drunk was regular or sweetened.
In Singapore at that time, Mueller says, there was very little intake of diet soda.
"We followed the participants for 14 plus years, keeping track of different cancers," he tells WebMD.
They found 140 cases of pancreatic cancer and looked back to see if there was an association with sodas or juices.
Sodas and Pancreatic Cancer Risk: Study Results
The researchers divided the consumption of sodas and juices into three categories: none, less than two servings a week, or two or more servings a week.
Those who drank two or more a week -- the average number was five -- had the 87% increased risk, Mueller tells WebMD.
No link was found between juices and pancreatic cancer risk.
Why the link with sugary sodas? Mueller says they are not certain. "What we believe is the sugar in the soft drinks is increasing the insulin level in the body, which we think contributes to pancreatic cancer cell growth. That increase in insulin is what may be leading to the development of the cancer."
His team adjusted for other risk factors, such as advancing age, smoking, diabetes, and body mass index. The risk for pancreatic cancer rises with age.
Sodas and Pancreatic Cancer: Industry and Other Views
The beverage industry protested the results. ''The study has a lot of weaknesses in it," Richard Adamson, PhD, scientific consultant for the American Beverage Association in Washington, D.C., tells WebMD.
One example, he says, are the small numbers of pancreatic cancer cases. He points out that of the 140 cases, 110 of those people did not drink sodas, while 12 had less than two servings a week, and 18 had two or more servings a week.
''It has a small number of pancreatic cancer cases compared to the population studied," he tells WebMD.
Other studies have found no link, he tells WebMD.
In a statement attributed to Adamson, the American Beverage Association points to a 2008 study finding no such link. It also takes exception to the focus on soft drinks rather than overall dietary patterns.
''You can be a healthy person and enjoy soft drinks," the statement reads.
Susan Mayne, PhD, associate director of the Yale Cancer Center and professor of epidemiology at the Yale School of Public Health, called the study results ''intriguing" in a statement but cautioned that the study finding was based on a relatively small number of cases and does not prove cause and effect. She is an editorial board member of the journal. The study was funded by the National Cancer Institute.
Even though the new study has limitations, the findings do echo those of previous studies, says Laurence N. Kolonel, MD, PhD, a researcher at the Cancer Research Center and professor of public health at the University of Hawaii, Honolulu. With his colleagues, he evaluated the association between added sugars in the diet and pancreatic cancer risk, publishing the findings in 2007. “In our study, we found a positive association between high intake of fructose and pancreatic cancer,” he tells WebMD. “Since high-fructose corn syrup is the main sweetener in non-diet soft drinks, our findings and those of the present study are quite consistent.”