Analysis Links Aspirin Use to Reduced Risk of Several Digestive Tract Cancers

A recent analysis suggested that aspirin may be linked to a reduction in the risk of developing several cancers of the digestive tract, such as pancreatic and liver cancers.

Dubbed “the largest and most comprehensive analysis to date,” the study, which was published in the Annals of Oncology, included a systematic review and meta-analysis of all observational studies on aspirin and cancers of the digest tract published through March 2019. A total of 113 observational studies were included, of which 45 studies were on colorectal cancer and included 156,000 causes.

For the review, researchers estimated the pooled relative risk (RR) of cancer for regular aspirin use versus non-use, and whenever data were available, investigated the dose- and duration-risk relations. Regular aspirin use was defined as taking at least 1 or 2 tablets per week.

Overall, the results showed that regular aspirin use was associated with a reduced risk of:

• Colorectal cancer (RR=0.73, 95% confidence interval [CI]=0.69-0.78, 45 studies)

• Squamous-cell esophageal cancer (RR=0.67, 95% CI=0.57=0.79, 13 studies)

• Adenocarcinoma of the esophagus and gastric cardia (RR=0.61, 95% CI=0.49-0.77, 10 studies)

• Stomach cancer (RR=0.64, 95% CI=0.51-0.82, 14 studies)

• Hepato-biliary tract cancer (RR=0.62, 95% CI=0.44-0.86, 5 studies)

• Pancreatic cancer (RR=0.78, 95% CI=0.68-0.89, 15 studies)

Additionally, 10 studies of head and neck cancer did not show a significant reduction in risk, according to the data.

The analysis also looked at the effect of aspirin dose and duration on colorectal cancer; an aspirin dose between 75 mg and 100 mg per day was associated with a 10% reduction in an individual’s risk of developing the cancer compared with non-users. A dose of 325 mg per day was associated with a 35% reduction, and a dose of 500 mg per day was associated with a 50% reduction risk, according to the study. However, the researchers noted that the estimate for high-dose aspirin was based on just a few studies, so these findings should be interpreted cautiously. Choice of dose should also take into consideration the potential risk of stomach bleeds, according to the researchers.

In addition to stomach bleeds, the potential adverse effects associated with aspirin include bleeding in other parts of the body and, occasionally, hemorrhages.

Compared with non-users, individuals who took aspirin had a declining risk of colorectal cancer for up to 10 years. This risk was reduced by 4% after 1 year, 11% after 3 years, 19% after 5 years, and 29% after 10 years, according to the results.

“These findings suggest there’s a beneficial effect of aspirin in the prevention of bowel and other cancers of the digestive tract,” senior author Carlo La Vecchia, MD, professor of epidemiology at the School of Medicine, University of Milan, said in a press release about the study. “The results for bowel, [esophageal], and pancreatic cancers are consistent with evidence from clinical trials on aspirin in the prevention of heart and blood vessel diseases.”

Among the possible limitations of the study are the inherent biases of observational studies, the researchers wrote. They noted that the inverse associations observed in the meta-analysis are generally stronger in case-control than cohort studies.

References:

1. Bosetti C, Santucci C, S Gallus, et al. Aspirin and the risk of colorectal and other digestive tract cancers: an updated meta-analysis through 2019. Annals of Oncology. 2020. https://www.annalsofoncology.org/article/S0923-7534(20)36073-7/pdf.

2. Aspirin Linked to Reduction in Risk of Several Cancers of the Digestive Tract. Press Release. European Society of Medical Oncology; April 16, 2020. Accessed April 16, 2020. https://www.esmo.org/newsroom/press-office/aspirin-reduction-in-risk-digestive-tract-annals-of-oncology.