Harvey Risch, MD, PhD
These findings help to make a case for medical experts who have been studying the effects of aspirin on pancreatic cancer for years.
“What’s interesting is that this association has become stronger with time across 19 studies that it appears to be a real association,” Harvey Risch, MD, PhD, a professor of epidemiology in the Department of Chronic Disease Epidemiology at the Yale School of Public Health, said in an interview. “It starts to get at the mechanisms of how pancreatic cancer develops and we can start to find out ways to act to reduce people’s risks.”
Researchers recruited 761 patients newly diagnosed with pancreatic cancer from 37 hospitals in Shanghai, China from December 2006 to January 2011. A control group of 794 participants was selected from the Shanghai Residents Registry.
In-person interviews were conducted to determine when each individual started using aspirin, the number of years they used the drug, and when they stopped taking it. Of those who took aspirin, almost all used it daily. Researchers did not distinguish between regular aspirin and low-dose aspirin use, but, according to Risch, they believe the majority were taking low-dose aspirin.
Adjustments were made for the following factors: body mass index, smoking history, and history of diabetes. The one limitation to the study’s findings is that researchers relied on participants to accurately report past aspirin use.
Overall, researchers found that using aspirin regularly was associated with a 46% decreased risk for pancreatic cancer in this population. Risk decreased by 8% for each year of aspirin use.
While it is not clear at this time why aspirin has such benefits, Risch said that it may reduce the grow rate of precancerous conditions in the pancreas.
The US Preventive Services Task Force recommends low-dose for certain individuals to reduce their risk of cardiovascular disease and colorectal cancer. Risch added that people who are taking aspirin to prevent these diseases are most likely preventing their risk of pancreatic cancer, too.
But this does not mean that aspirin is right for everyone, as in rare cases it does cause gastrointestinal bleeding or bleeding in the brain.
“This is something that each person has to work out with their healthcare provider to estimate what their risks will be,” said Risch. “This is relevant for people who have family histories, who have expressed risk factors for these other diseases, or if they have a strong family history of pancreatic cancer or perhaps breast or ovarian cancer, which has pancreatic as one of the lesser subtypes for the BRCA1 and BRCA2 mutation family.”
Past studies have shown similar findings regarding aspirin use. For instance, a study published 2 years ago in the same journal, found that men and women had a 48% lower risk of pancreatic cancer if they regularly used aspirin. This study was conducted among patients in Connecticut.
“You have to be careful with it [aspirin] in general. Not people who take it once in a while like for arthritis or pain relief, but in general use of using aspirin day in and day out on a regular basis—even low-dose aspirin needs to be decided on with a careful calculation of the pros and cons,” reminded Risch.
Though pancreatic cancer is rare—only 1.5% of adults in the United States will be diagnosed with it in their lifetime—it is one of the deadliest types of cancer. In fact, it is the third leading cause of cancer-related deaths in the United States and has a 5-year relative survival rate of less than 8%, according to the National Cancer Institute.
Risch plans to expand on his research by working on studies to facilitate earlier diagnosis of pancreatic cancer.
Risch HA, Lu L, Streicher SA, et al. Aspirin use and reduced risk of pancreatic cancer [published online December 20, 2016 ahead of print]. Cancer Epidemiol Biomarkers Prev.