An aspirin a day may reduce the risk of colon cancer, a major study suggests.
Those who took the anti-inflammatory pill were a third less likely to develop the fatal disease over their lifetime than those who did not take it.
The drug worked even in the sickest people: they smoked, drank alcohol and were obese, all of which put them at risk for colon cancer.
Aspirin is thought to prevent colon cancer by blocking the formation of polyps, which can become cancerous, and by reducing enzymes that prevent tumor growth.
The team believes the findings could lead more doctors to recommend aspirin to prevent colorectal cancer, which has reached epidemic levels among young Americans.
Mass General Brigham researchers found that taking aspirin regularly reduced the risk of colorectal cancer by up to 40 percent.
The graph above shows the percentage of participants who developed colorectal cancer, including those who took aspirin and those who did not.
Dr. Daniel Sikavi, senior author of the study and a gastroenterologist at Mass General Brigham, said: “Our results show that aspirin can proportionally reduce the markedly elevated risk in those with multiple risk factors for colorectal cancer.”
‘In contrast, those with a healthier lifestyle had a lower baseline risk of colorectal cancer and therefore their benefit from aspirin was still evident, although less pronounced.’
The U.S. Preventive Services Task Force has virtually recommended that all adults ages 50 to 59 (those at highest risk for colorectal cancer) take a low-dose aspirin every day to prevent the disease.
However, the nine-cent drug has been linked to dangerous internal bleeding, which has discouraged many doctors from recommending its regular use.
Colon cancer is one of the deadliest forms of the disease, as its symptoms, such as rectal bleeding, are often mistaken for more benign problems, making prevention a priority. The disease is estimated to kill more than 50,000 Americans this year, making it the second-deadliest form of the disease behind lung cancer.
For the latest study, researchers at Mass General Brigham Hospital in Boston recruited 100,000 adults ages 18 to 19 and asked half to take regular daily or weekly doses of aspirin.
Researchers recruited 107,655 men and women from the Nurses’ Health Study and the Health Professionals Follow-up Study and followed them for 30 years. The average age of the participants was 49 years.
Participants completed questionnaires about their lifestyle habits, such as diet, exercise, alcohol and tobacco use.
Of those taking the drug, one group took two regular-dose pills per week or one low-dose pill per day.
Those taking aspirin regularly took two or more standard pills per week (325 mg) or one low-dose pill (81 mg) per day.
Among those who took aspirin regularly, 1.98 percent developed colorectal cancer compared with 2.95 percent of those who did not take the drug.
After adjusting for factors such as family history, this equates to a 33 percent lower risk of colorectal cancer for the aspirin group, the team said.
And the benefits were most pronounced in those who reported unhealthy lifestyle habits: These aspirin-taking participants had a 38 percent lower risk of developing the disease than unhealthy participants who did not take aspirin.
However, those with healthier lifestyles benefited the least from aspirin, with a seven percent reduced risk compared with those who did not take the pills.
The team said the results could lead doctors to “more strongly” recommend aspirin to patients who lead unhealthy lifestyles.
The findings come amid a worrying rise in colorectal cancer in Americans under age 50.
Dr. Andrew Chan, co-senior author of the study and director of Epidemiology at the Mass General Cancer Center, said: “Aspirin likely prevents colorectal cancer through multiple mechanisms.”
For example, the team believes that aspirin reduces the production of prostaglandins, inflammatory proteins that have been shown to promote the growth of cancer cells.
Colon cancer tumors have been shown to have elevated levels of the enzyme COX-2, which produces inflammatory proteins called prostaglandins.
These have been shown to promote the growth of colorectal cancer cells, and chronic inflammation is also a primary risk factor for colorectal cancer.
Aspirin has also been shown to reduce the risk of colorectal adenomas, a type of polyp or abnormal growth that can develop into cancerous colon tumors.
The new research has several limitations, including focusing primarily on white health care professionals. Data on lifestyle factors were also self-reported, which can lead to bias.
The study was published Thursday in JAMA Oncology Journal.