"We saw a 22% higher risk of pancreatic cancer in those who drank two or more alcoholic beverages a day compared to nondrinkers," says study researcher Jeanine M. Genkinger, PhD, an assistant professor of oncology at the Lombardi Comprehensive Cancer Center at Georgetown University, Washington, D.C. That risk is termed ''modest'' by Genkinger and her co-researchers.
Pancreatic cancer, often deadly because it is difficult to diagnose early, was found in nearly 38,000 people in the U.S. in 2008, according to the American Cancer Society. An estimated 6% of U.S. cancer deaths in 2008 were attributed to pancreatic cancer in both men and women.
Two recent high-profile patients include actor Patrick Swayze and Supreme Court Justice Ruth Bader Ginsburg.
Alcohol and Pancreatic Cancer: Study Details
Research about alcohol intake as a risk factor for pancreatic cancer has produced conflicting findings. Heavy alcohol intake has been linked to both chronic inflammation of the pancreas (pancreatitis) and type 2 diabetes, both associated with an increased pancreatic cancer risk. But studies about alcohol intake haven't been clear.
So, Genkinger and her colleagues pooled the results of the 14 previously published research studies on alcohol intake and pancreatic cancer that included nearly 863,000 men and women, with data available about their dietary habits before the cancer diagnosis.
In the study sample, 2,187 men and women were diagnosed with pancreatic cancer.
First, Genkinger's team looked at men and women together, finding the 22% increase in risk for two or more drinks a day. One drink went by the standard definitions -- 12 ounces of beer, 4 ounces of wine, or 1.5 ounces of 80-proof liquor.
"When we looked at men and women separately, the women who drank two or more a day had a 41% increased risk compared to nondrinkers," Genkinger says. "That was statistically significant."
Men who drank two or more drinks a day had a 12% increased risk compared to nondrinkers, which was not statistically significant. So they looked further.
When men drank more than three, the risk rose to nearly 60% compared to nondrinkers, when looking at a specific kind of pancreatic cancer, an adenocarcinoma. That was a significant association. The majority of pancreatic cancers are adenocarcinomas.
The effect was the same regardless of type of alcohol, she says. "It doesn't appear to be associated with a specific beverage; it is associated with total alcohol intake."
Why alcohol boosts risk isn't known, but one of several theories is that a by-product of alcohol metabolism acts as a co-carcinogen.
The researchers also found that the link between alcohol and pancreatic cancer was stronger for those of normal weight than for obese or overweight participants. "Obesity is thought to be strongly associated with pancreatic cancer," Genkinger says. So it could be that in the study, the strong obesity connection masked the connection with alcohol for the overweight participants, she says.
Smoking is also a risk factor for pancreatic cancer.
The study was supported by the National Cancer Institute and is published in the March issue of Cancer Epidemiology, Biomarkers and Prevention.
Peter Shields, MD, deputy director of the Lombardi Comprehensive Cancer at Georgetown University but not a co-researcher of the study, reviewed the paper for WebMD and put the findings in perspective. Excess alcohol intake is already known to play a role in many cancers, he says, including esophageal, oral, liver, and breast cancers.
"Now there is some reasonable evidence it might also cause pancreatic cancer," Shields says.
"No single study is ever definitive," he adds. But, being an analysis of previously published studies, the new report, he says, is "better than a single study."
The Best Alcohol Advice?
At the least, he says, people should be aware of the new findings.
Genkinger notes that based on their findings, the standing advice from the American Cancer Society and American Heart Association -- limit consumption to no more than two drinks a day for men and one for women -- makes sense.