This is true even it’s taken in the lowest possible dose of 75 milligrams daily, shows a study published online in the journal Gut.
The protective effect begins after just one year -- in the general population and not just in those who are considered to be at risk of developing the disease, which kills almost half a million people worldwide each year.
Low-Dose Aspirin vs. Colorectal Cancer
Previous research has shown that aspirin protects against colorectal cancer, but no study has determined the most effective dose and how long it must be taken, study researchers say in a news release.
Researchers examined records for about 2,800 people with colorectal cancer, as well as 3,000 healthy people, matched for sex, age, and where they live.
The patients completed food frequency and lifestyle questionnaires so investigators could assess their usual diet and lifestyle choices, which are known to have an effect on the risk of developing bowel cancer.
Researchers then tracked bowel cancer survivors and people who had developed the disease over a five-year period.
The study shows that taking daily low-dose aspirin was associated with a 22% reduced risk of developing the disease. After five years, taking low-dose aspirin reduced risk by 30%.
But the researchers also found that increasing the dose may not be necessary or helpful, a finding they describe as crucial.
Researchers found that 354 or 15.5% of patients with colorectal cancer were taking low-dose aspirin, compared to 526 or 18% of disease-free people. They also found that taking any nonsteroidal anti-inflammatory drug (NSAID) on a regular basis lowers risk of developing colorectal cancer. Some commonly used NSAIDs are aspirin, ibuprofen, and naproxen.
The study also shows that NSAID use before receiving a diagnosis of colorectal cancer does not influence survival time from the disease.
The researchers conclude that their study is the first to show a protective effect against colorectal cancer when even the lowest dose of aspirin is taken. The effect is noted as early as one year after regular use but increases with time for up to 10 years.