Date published: 2007/05/11
The BBC says:
Taking aspirin each day can prevent bowel cancer developing, a study says.
Oxford University researchers said taking a dose of 300mg a day for five years offered the protection.
Long-term aspirin use is generally not backed because of the risk of stomach problems, but the team said it could benefit those at high-risk of cancer.
...
The researchers looked at the results from two large-scale UK trials carried out in the late 1970s and early 1980s covering over 7,500 people which had given some people 300, 500 or 1,200mg per day doses of aspirin or a dummy pill for five to seven years.The people in the study were then followed for up to 20 years, and deaths from bowel cancer were logged.
The team say it takes at least 10 years to see an effect, because that is how long it takes for a pre-cancerous growths to develop into cancer.
Other studies have examined aspirin's benefits.
However, this was the first where people were allocated to take different doses of the drug, or the fake version, rather than looking back at the aspirin use of bowel cancer patients and comparing them with healthy people.
The researchers found that taking 300mg of aspirin - the equivalent of one pill - a day for five years reduced the incidence of bowel cancer by 74% in the subsequent 10 to 15 years.
An accompanying review of 30 observational studies suggested taking medium-to-high doses of aspirin for 10 years or more reduced the risk of developing the disease by 50%-70%.
The protective effect of aspirin appeared to be consistent regardless of age, sex, race or country of origin.
It was also seen in individuals who had a close family relative with bowel cancer, which normally raises the lifetime risk two to four times.
Professor Peter Rothwell, who led the research, said: "What we are saying is that for a subgroup of people at high risk of bowel cancer, they probably aren't going to be dramatically harmed by taking aspirin.
"They may have some risk of bleeding in the stomach, but they will see potentially significant benefits in the reduction of their colon cancer risk.
"In that situation, I think taking aspirin daily would be worthwhile."
So one day the BBC tells us that aspirin may increase the risk of strokes and the next day they tell us that aspirin is a wonder drug for bowel cancer. At least this study seems to have been done properly (unlike most health studies) in that the "people were allocated to take different doses of the drug, or the fake version, rather than looking back at the aspirin use of bowel cancer patients and comparing them with healthy people". This is the main way you can prove a causation rather than just a correlation. (Well, this is assuming the people were assigned to the groups randomly.)
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