Aspirin continues to amaze
FOR thousands of years aspirin has been humanity’s wonder drug. Extracts from the willow tree have been used for pain relief in folk medicine since the time of the ancient Greeks. By 1897 a synthetic derivative (acetyl salicylic acid) of the plant’s active ingredient (salicin) was created. This allowed aspirin to become the most widely used medicine in the world.
In recent years its benefits as a blood-thinning drug have led to it being prescribed in low doses of around 50mg to reduce deaths from stroke and heart attack. There were also hints that aspirin may help prevent some cancers. But these were mostly based on observational studies, which can be misleading.
The gold standard of scientific evidence is the randomised controlled trial, preferably one with a lot of people and held over a long time. The results of just such a trial, published in the Lancet, suggest that aspirin is indeed an astonishing drug. Peter Rothwell at the John Radcliffe Hospital in Oxford and his colleagues looked at deaths due to cancers during and after randomised trials of daily aspirin. The trials had actually been started to look at how useful aspirin was for preventing heart attacks and strokes. Nevertheless, the data from the 25,570 patients enrolled in eight trials was also revealing about cancer.
In trials lasting between four and eight years, the patients who had been given aspirin were 21% less likely to die from cancer than those who had been given a placebo. These results were based on 674 cancer deaths, so are unlikely to represent the kind of statistical oddity that can beset studies on cancer risks that sometimes create headlines.
The benefits of aspirin were also apparent many years after the trials had ended. After five years, death rates for all cancers fell by 35% and for gastrointestinal cancers by 54%. A long-term follow-up of patients showed that the 20-year risk of cancer death remained 20% lower in those who had taken aspirin.