By Randy Dotinga
The Chinese-based study couldn't prove cause-and-effect. However, "the balance of evidence shows that people who use aspirin to reduce risk for cardiovascular disease or colorectal cancer can feel positive that their use likely also lowers their risk for pancreatic cancer," said study lead author Dr. Harvey Risch.
He's professor of epidemiology at the Yale School of Public Health and Yale Cancer Center in New Haven, Conn.
According to the American Cancer Society, about 53,000 Americans will be diagnosed with pancreatic cancer this year, and almost 42,000 will die from the disease. Pancreatic cancer is often a "silent killer" because symptoms do not emerge until the tumor is advanced.
The new study tracked 761 people diagnosed with pancreatic cancer in Shanghai from 2006 to 2011, and compared them to 794 people who didn't have the cancer.
All the participants were asked about whether they took low-dose aspirin on a regular basis. Almost all who said they took it did so on a daily basis.
Eighteen percent of the non-cancer patients reported regular use of low-dose aspirin compared to 11 percent of the pancreatic cancer patients.
After adjusting their statistics so they wouldn't be thrown off by various factors, the researchers estimate that aspirin may reduce the already small risk of pancreatic cancer by 46 percent.
However, Risch's team stressed that the study doesn't prove that aspirin directly produces a lower risk, and the participants may not have precisely remembered their aspirin intake.
An analysis of other studies found similar results. The researchers examined 18 other studies that had investigated aspirin use and pancreatic cancer risk over the past two decades and found that as aspirin use increased, the risk of pancreatic cancer significantly decreased.
"Pancreatic cancer is relatively rare -- just 1.5 percent of U.S. adults will be diagnosed with it at some point during life -- and regular aspirin use can cause appreciable complications for some," Risch said in a news release from the American Association for Cancer Research. "Therefore, a person should consult his or her doctor about aspirin use."
One oncologist who reviewed the data said Americans should be cautious in interpreting the results.
"This is an interesting study that suggests that regular aspirin use may reduce the incidence of pancreas cancer -- in people living in China," said Dr. Tony Philip, an oncologist at Northwell Health Cancer Institute in Lake Success, N.Y.
"Anything more than that cannot be extrapolated from this study," he said. "We know the genetics of people in one part of the world is very different from other parts. In addition, we don't know what else these patients were doing, for example, taking herbal medicine, their family history, or access to medical care."
Philip said that he wouldn't suggest daily low-dose aspirin to his patients based on this data alone. But the findings "can be the basis for further work" researching this issue, he added.
The study was published Dec. 20 in Cancer Epidemiology, Biomarkers & Prevention.