Under direction from their doctors, many patients take daily aspirin to lower risks for heart attacks. But a new study, conducted by researchers at the Yale School of Public Health in New Haven, CT, suggests the longer a person takes low-dose aspirin, the lower his or her risk for pancreatic cancer.
The research, led by Dr. Harvey A. Risch, professor of epidemiology at Yale, is published in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research.
According to the National Cancer Institute, in 2014, there will be an estimated 46,420 new cases of pancreatic cancer in the US and an estimated 39,590 deaths from the disease.
The pancreas is an organ located in the abdomen that helps the body digest food and use its energy. When cells in the pancreas grow out of control, they can turn into cancerous tumors.
Pancreatic cancer is difficult to detect and diagnose early because there are not any noticeable signs or symptoms during early stages of the disease. Furthermore, when symptoms are present, they are similar to the signs of many other conditions.
"Because about 1 in 60 adults will get pancreatic cancer and the 5-year survival rate is less than 5%," says Dr. Risch, "it is crucial to find ways to prevent this disease."
He explains that older studies involving aspirin "have been clouded by the use of [regular- or high-dose] aspirin for pain relief from conditions that themselves might be related to the risk for pancreatic cancer."
But recently, individuals have been using low-dose aspirin for long periods of time to prevent cardiovascular disease, so Dr. Risch and his team wanted to assess how such use could impact on risk of pancreatic cancer.
Greater risk reduction the longer a person has taken low-dose aspirin
To further investigate, the research team recruited study subjects from the 30 general hospitals in Connecticut between 2005 and 2009. In total, there were 362 pancreatic cancer cases and 690 controls.
Researchers found that the earlier a person started taking low-dose aspirin regularly, the greater their risk for pancreatic cancer reduced.
The researchers interviewed study subjects in person to determine when they started taking aspirin, the total number of years they used it, dosage used and when they stopped taking it.
Additionally, the team took into account certain confounding factors, such as body mass index, smoking history and history of diabetes.
The study subjects consisted of 57% men, 92% non-Hispanic white people, 49% former or current smokers and 19% had been diagnosed with diabetes within 3 years before the start of the study.
Of all participants, 96% were low-dose aspirin users, which was defined as a dose of 75-325 mg of aspirin per day. This is the amount usually taken for heart disease prevention. Any dose higher than that was considered as regular-dose aspirin.
Of the regular-dose aspirin users, 92% reported daily use.
Results showed that the earlier a person started taking low-dose aspirin regularly, the greater their risk for pancreatic cancer reduced. In detail, those who started 3 years before the study had a 48% risk reduction, and those who started taking it 20 years before the study experienced a 60% risk reduction.
Additionally, those who discontinued use of aspirin with 2 years of the start of the study experienced a threefold increased risk for pancreatic cancer, compared with continuing use.
Commenting on their findings, Dr. Risch says:
"There seems to be enough evidence that people who are considering aspirin use to reduce the risk for cardiovascular disease can feel positive that their use might also lower their risk for pancreatic cancer, and quite certainly wouldn't raise it."
'Larger studies needed'
Though their findings are significant, Dr. Risch notes that people who are developing cancer of the pancreas often have physiologic changes - which can include taste disorders - and this means such individuals are more likely to quit taking aspirin.
"So it may be tricky to separate the various aspects of patterns of aspirin use and risk of pancreatic cancer," he adds.
Speaking with Medical News Today, Dr. Risch further explained:
"Some individuals taking aspirin stop doing so because of these kind of subliminal disagreements, just as some smokers quit smoking during the 2-3 years before diagnosis of pancreatic cancer, because of some increasing discomfort with the smoking. So we have to be able to distinguish between currently using aspirin vs. quitting, vs. longer times of using aspirin."
He added that he and his team made sure to make this distinction in their study by looking at people who quit using aspirin compared with people still using aspirin.
Regarding further research, Dr. Risch told us they need to conduct larger studies "to be able to make more precise conclusions."
They also have a pancreas cancer research consortium - called PanC4, the Pancreatic Cancer Case-Control Consortium - that is pooling studies to address aspirin use. He said that work will be completed in about a year.
Despite their promising findings, Dr. Risch cautions that "aspirin use has potential risks of its own, and thus the risks and benefits for each person have to be evaluated based on personal characteristics and considerations."