More Evidence of Aspirin's Benefits in Reducing Colorectal Cancer Risk

Andrew T. Chan, MD, MPH

A recent study joins a body of evidence suggesting that long-term, regular aspirin use is associated with a reduced risk for cancer, with the most dramatic reduction being seen in colorectal cancer incidence. The research was presented at the 2015 AACR Annual Meeting.

“Previous studies of aspirin and cancer have been limited in terms of their size, length of follow-up, or ability to examine aspirin use in the context of other lifestyle factors,” Yin Cao, MPH, ScD, a research fellow in the Department of Nutrition at the Harvard School of Public Health, said in a statement. “Our research provides critical information regarding the full constellation of potential benefits of aspirin use, at a range of doses, timing, and duration of use, within a large population of individuals.”

For the study, data were collected on aspirin use, cancer diagnoses, and other risk factors every other year from 82,600 women participating in the Nurses’ Health Study and 47,651 men from the Health Professionals Follow-up Study. After 32 years of follow-up, 27,985 incident cancers were recorded.

Study participants who had two or more aspirin tablets per week had a 5% lower risk for cancer, compared with non-regular aspirin users. In gastrointestinal (GI) cancers, the risk was lowered by 20%, including a 25% reduction in colorectal cancers and a 14% reduction in gastroesophageal cancers. No association was found between regular aspirin use and a decreased risk for breast, lung, or advanced prostate cancers.

Significant risk reduction was seen only after 16 years of aspirin use and was no longer evident within 4 years of discontinuing use. The risk reduction was similar for women and men and not affected by the individual’s race, history of diabetes, family history of cancer, body mass index, and smoking history.

Previous studies have shown that long-term use of aspirin has lowered the risk of cardiovascular events, including heart attack and stroke. Senior study author Andrew T. Chan, MD, MPH, director of the Gastroenterology Training Program at Massachusetts General Hospital, who presented the study at AACR, said that these most recent findings suggest that even for those individuals who may not need the cardiovascular protective benefits of aspirin, the cancer prevention effect would make consumption worthwhile, and more research is warranted.

“Based on these data, there is the possibility that aspirin could have a significant clinical benefit for many individuals, since both cardiovascular disease and cancer are leading causes of death in the United States,” Chan explained. “The next step is to confirm these findings in additional populations and conduct further studies examining the potential impact of novel biomarkers which can be used to better personalize who should be treated.”

In that vein, Chan is also giving a plenary talk at the AACR meeting on molecular risk stratification for aspirin chemoprevention. He is an investigator on a recently published international study which found that the preventive benefit of aspirin and NSAIDS may be linked to variations in an individual’s DNA.2

Analyzing data from 10 large population-based studies, researchers found that although regular use of aspirin and NSAIDs was associated with an overall reduction in the risk of colorectal cancer, no protective effect was seen among about 9% of the participants who had genetic variations on chromosome 15. Additionally, approximately 4% of participants with variations on chromosome 12 were found to be at increased risk of colorectal cancer.

Coa cautioned against general aspirin use for cancer prevention, primarily because there are risks with aspirin, such as GI bleeding. A more tailored approach, including using biomarker research Chan mentioned, may turn out to be best.

References

• Cao Y, Nishihara R, Wu K, et al. Long-term aspirin use of aspirin and risk of cancer. Presented at: 2015 AACR Annual Meeting; April 18-22; Philadelphia, PA. Abstract 3197.
• Nan H, Hutter CM, Lin Y, et al. Association of aspirin and NSAID Use with risk of colorectal cancer according to genetic variants. JAMA. 2015;313(11):1133-1142.