Numerous studies have associated the use of aspirin and other nonsteroidal anti-inflammatory drugs, or NSAIDs, with reduced risk of colorectal cancer. But according to a new study published in JAMA, this effect may depend on certain genetic variations an individual possesses.

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While researchers found an overall reduced risk of colorectal cancer with regular aspirin and/or NSAID use, this was not the case for participants with specific genetic variations.

In July 2013, a study of almost 40,000 women published in the Annals of Internal Medicine associated low-dose aspirin use with a 20% reduced risk of colorectal cancer.

While many other studies have reported similar findings with use of aspirin and other NSAIDs, the researchers of this latest study – including Dr. Andrew T. Chan of Massachusetts General Hospital in Boston – say the mechanisms behind this link are unclear.

“Routine use of aspirin, NSAIDs, or both for chemoprevention of cancer is not currently recommended because of uncertainty about risk-benefit profile,” the team notes.

As such, they believe gaining a better understanding of how aspirin and NSAIDs interact with certain gene variants may help identify which populations are most likely to see colorectal cancer prevention benefits with the use of these medications.

To reach their findings, the researchers conducted a genome-wide analysis of 10 studies initiated from 1976, involving 8,634 patients with colorectal cancer and 8,553 matched controls.

Information on participants’ use of aspirin, NSAIDs or both was collected in each study, and the researchers investigated how the medications interacted with single-nucleotide polymorphisms (SNPs) – DNA sequence variations – among participants and how this influenced their risk of colorectal cancer.

Fast facts about colorectal cancer
  • Approximately 1 in 20 people in the US will develop colorectal cancer at some point in their lifetime
  • Colorectal cancer is the second leading cause of cancer-related death in the US, though the death rate from the disease has fallen over the past 20 years
  • There are now more than 1 million survivors of colorectal cancer living in the US.

Learn more about colorectal cancer

The results of the analysis revealed that, overall, participants who regularly used aspirin, NSAIDs or both were at lower risk of colorectal cancer, compared with those who were irregular users of these medications.

However, on assessing the results by participants’ genotypes, the team found regular use of aspirin and/or NSAIDs among participants who possessed two variants of the SNP rs16973225 – AC or CC – did not appear to affect the risk of colorectal cancer, while two rare variants of the SNP rs2965667 – TA or AA – was linked to an increased risk of colorectal cancer among regular aspirin and/or NSAID users.

The researchers point out that both of these SNPs are relatively rare; rs16973225 was only identified among 9% of participants, while rs2965667 was only found among 4% of participants.

Still, the team believes the findings are important for identifying which individuals are most likely to see reduced colorectal cancer risk with regular aspirin and/or NSAID use. “Validation of these findings in additional populations may facilitate targeted colorectal cancer prevention strategies,” they add.

In an editorial linked to the study, Dr. Richard C. Wender, of the American Cancer Society, says the findings from Dr. Chan and colleagues may bring us a step closer to “affordably and efficiently” conducting genetic testing in order to reduce disease risk in healthy individuals.

“It will be important for primary care clinicians to understand genetic risk and to have informed, clear, literacy-adjusted, culturally competent discussions with their patients about how to use this information,” he adds, “otherwise, the goal of using genetic information to enhance decision making about prevention will remain elusive. Research needs to test different approaches to translating this complex information into practical methods to share information and improve clinical decisions.”

Earlier this month, Medical News Today reported on a study published in JAMA Internal Medicine that associated a vegetarian diet with a 22% reduced risk of colorectal cancer.