A recent study intended to verify that small doses of aspirin did reduce the chances of heart attack and stroke has also shown that it reduces the incidence of certain cancers:
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.
The study revealed that the effect takes time to accrue, so aspirin must be taken over a long period. The latent period for improving oesophageal, pancreatic, brain and lung cancer was about five years of aspirin taking on a daily basis. For stomach and colorectal cancer the effects took ten years and for prostate cancer about 15 years. The means by which aspirin prevents cancer is not well understood. It is believed that it inhibits an enzyme that promotes cell proliferation in tumours.
