According to a new study, regular and long-term use of aspirin and Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) cuts down the risk linked with colorectal cancer.
However, use of aspirin for chemoprevention of colorectal cancer might require using the drug at doses that are higher than recommended over a long period of time.
This might cause serious side effects including gastrointestinal bleeding.
"While the results of our study show that aspirin should not currently be recommended for the chemoprevention of colorectal cancer in a healthy population, there is a need for further studies to help identify for which patients the potential benefits outweigh the risks," said Andrew T. Chan, MD, MPH, Massachusetts General Hospital and lead author of the study.
"We also need to improve our understanding of how aspirin works to prevent and inhibit the formation of colorectal cancer," added Chan.
In the study, the participants were enrolled in the Health Professionals Follow-up Study, a large prospective cohort study, which has provided detailed and updated information on aspirin use.
The Health Professionals Follow-up Study has been conducted on 51,529 male dentists, optometrists, osteopaths, podiatrists, pharmacists and veterinarians, who returned a mailed health questionnaire in 1986.
The questionnaire consisted of questions based on diet, aspirin use and medical diagnoses, including cancer.
The biennial questionnaires ask for updated information including cancer diagnoses and aspirin use. The participants were between 40 and 75 years of age when the study began.
The research team found that men who used aspirin regularly experienced a significantly lower risk of colorectal cancer, including distal colon cancer, proximal colon cancer and rectal cancer, even after controlling for other risk factors.
The reduction in risk was seen in both early (stage I/II) and advanced (stage III/IV) colorectal cancers.
There were 975 documented cases of colorectal cancer over 761,757 person-years, among the 47,636 eligible men. Participants who reported regular aspirin use, equal to or more than twice a week, were older, more likely to have smoked, used multivitamins and folate, and consumed slightly more alcohol.
In an average-risk population of men, results showed that the benefit of aspirin was not apparent until after more than five years of use.
The greatest reduction in risk was observed at cumulative doses of more than 14 standard tablets (325 mg) per week, which is higher than normally recommended.
The advantage of aspirin use appears to diminish less than four years after stopping use and is not evident after four to five years of discontinued use.
The study is published in Gastroenterology, the official journal of the American Gastroenterological Association (AGA) Institute.