Research highlights remarkable effects of drug
IF YOU were to find yourself marooned on a desert island, and you had just one bottle of medication, which drug would you choose? After last week’s groundbreaking news on the cancer-preventing powers of aspirin, I am in no doubt what I would select. Already established as one of the most broadly effective drugs ever, aspirin has now become a “superdrug”.
Researchers from Oxford University found that taking aspirin reduced overall cancer mortality by one-fifth. But what was especially remarkable was the reduction in such a broad range of cancers. The 20-year risk of death was reduced by about 10 per cent for prostate cancer, 30 per cent for lung cancer, 40 per cent for colorectal cancer and 60 per cent for oesophageal (gullet) cancer.
Benefits were seen after taking aspirin for five years for oesophageal, pancreatic, brain and lung cancer. Taking aspirin for 10 years reduced death from stomach cancer, while mortality from prostate cancer dropped after taking aspirin for 15 years.
This is a truly remarkable effect. Those of us taking a daily dose of aspirin for at least five years for cardioprotective reasons have already garnered some additional benefits from this remarkable pill. And anyone starting the drug in their 40s and 50s, who will be on aspirin for 20 years or more, will likely reap the most benefit.
Why doesn’t everyone take 75mg of aspirin from middle age onwards? Well, until now, experts felt that the benefit in terms of reduced strokes and heart attacks was insufficient to balance the risk of aspirin causing bleeding in the gastrointestinal tract. Now, however, the reduction in deaths from a range of common cancers will probably alter the risk-benefit equation in favour of taking daily aspirin.
Like many of our earlier drugs, aspirin has its origin in nature. The bark of the willow tree became known as the “fever tree” following reports of its miraculous properties. An Argentinian monk called Calantha who lived in Peru described how the bark, made into a powder and given as a beverage, cured people of high fevers. The Jesuits imported the bark into Europe in the 17th century, where it became known as Peruvian Bark.
Two centuries later, the active ingredient of the bark was isolated as quinine, which has a characteristically bitter taste. Salicylic acid was a further refinement, but produced irritant side effects, especially of the stomach and gullet. This problem was solved by the work of Felix Hoffman, a young German chemist working for the pharmaceutical firm Bayer, with the production of a powder containing acetyl salicylic acid.
Remarkably, it was not until 30 years ago that its precise mechanism of action was discovered. Sir John Vane won the Nobel Prize for his discovery of aspirin’s ability to halt the body’s production of chemicals called prostaglandins. These are released when cells are injured and produce the characteristic symptoms of inflammation, including swelling and pain.
Bowel cancer is also linked with high levels of a chemical called prostaglandin in the bowel wall. We know that aspirin and other anti-inflammatory drugs
inhibit an enzyme called cyclo-oxygenase (Cox) which is needed to produce prostaglandin. As a proven Cox inhibitor, aspirin helps to block the inflammatory chemicals which are associated with colon cancer. And while there may be other mechanisms – as yet undiscovered – at play, this anti-Cox action is key to aspirin’s protection against the broad range of cancers.
Another issue that will now need to be addressed is whether those patients who require other long-term anti-platelet treatments should be changed to aspirin in order to garner the extra public health benefits. The Oxford team has calculated that even allowing for fatal bleeding from aspirin, taking the drug for five to 10 years reduces mortality from all causes by about 10 per cent. In terms of cost effectiveness, this level of benefit exceeds that of some established cancer screening programmes. It may even justify the costs of co-prescribing acid-suppressing drugs with aspirin to reduce any bleeding complications.
We may well have reached the point where an aspirin a day really does keep the doctor away.