BOB DOUGHTY: Two years ago, European researchers reported that aspirin may have what they called a “long-term protective effect against colorectal cancer.” Peter Rothwell of the University of Oxford led the researchers. They examined twenty years of results from four large studies.

The studies involved fourteen thousand people. Some of them took a seventy-five milligram baby aspirin once a day. Others took a three hundred milligram, adult-sized aspirin.

The researchers found that people who took one aspirin a day for about six years reduced their risk of colon cancer by twenty-four percent. And deaths from the disease dropped by thirty-five percent. That was in comparison to those who took a harmless substance or nothing at all.

FAITH LAPIDUS: Last week, the Lancet published the combined results of a larger observational study, also led by Professor Rothwell. This time, he and researchers examined eight studies that involved more than twenty-five thousand individuals.

They found that taking a small aspirin once a day reduced death rates from a number of common cancers. Taking seventy-five milligrams of aspirin daily for five years reduced the risk of bowel cancer by one-fourth. Deaths from the disease fell by one-third.

BOB DOUGHTY: Aspirin does not help everything, however. It can cause problems. For example, it can interfere with other medicines, although this is true of many drugs. Also, some people should not take aspirin. People who take other blood thinners or have bleeding disorders are among this group. Pregnant women are usually told to avoid aspirin.