Cancer study: Genomes may predict aspirin's benefits

INDIANAPOLIS — Doctors have known for a while that aspirin and other non-steroidal anti-inflammatory drugs, known as NSAIDs, may help protect some people against colorectal cancer. They also have known that not everyone can benefit.

But they haven't known how to separate those who will benefit from those who won't. An article in this week's Journal of the American Medical Association, authored by an Indiana University Simon Cancer Center researcher and colleagues elsewhere, takes the first step to answering that question by identifying a few genetic markers that seem to make the difference.

"This is a kind of personalized prevention strategy," said Hongmei Nan, also a research associate professor at the Richard M. Fairbanks School of Public Health at Indiana University-Purdue University Indianapolis.

Because long-term use of these drugs also can lead to intestinal bleeding and other unwanted side effects, prescribing aspirin as a general preventive measure does not make sense.

The authors looked at the genomes of 8,634 people who had had colorectal cancer and compared them to 8,553 who did not. While overall there was a positive association between aspirin or NSAID use and reducing cancer risk, the researchers also found that about 9% of those studied, with one of two genotypes, saw no benefit.

Another 4% of participants, who had two other even rarer genotypes, actually appeared to experience higher risk of colorectal cancer if they took aspirin or NSAIDs regularly.

"This prevention effect is not for everybody, it does not work for everyone," Nan said. "This type of result has substantial clinical significance."

It may be awhile, however, before doctors start routinely testing people for whether they have any of these genetic variations, Nan said. For now, the study suggests future areas of research and could one day contribute to what doctors are calling precision medicine.

The idea, say the study's authors, is to identify those in the population for whom the benefit of taking aspirin or similar drugs would outweigh any risks associated with it.