The 15-PGDH gene encodes a member of the short-chain nonmetalloenzyme alcohol dehydrogenase protein family. The encoded enzyme is responsible for the metabolism of prostaglandins, which function in a variety of physiologic and cellular processes such as inflammation.

Scientists studied tissues from people who developed colon cancer while on an aspirin regimen then set out to understand why people with a particular gene appeared to get a protective benefit from aspirin and others did not.

They examined tissues of 270 colon cancer patients from 127,865 participants followed for over three decades.They found that patients who lacked a genetic profile which yields high levels of the enzyme 15-PGDH got almost no protective benefit for colon cancer from aspirin.

"If you looked at the folks from the study who had high 15-PGDH levels and took aspirin, they cut their risk of colon cancer by half," said senior author Sanford Markowitz of Case Western Reserve School of Medicine.