Long term daily intake of low doses of aspirin reduces the instances of colorectal cancer by one-fourth and the mortality rate from this disease by a third. This was announced recently in a study published by The Lancet. Doctors already recommend low daily doses of this cheap, over-the-counter medication to patients at risk of heart attack or stroke and now the latest report claims that high doses can prevent rectum and colon cancer. However, researchers also found that there could be some high risks involved in high dosages, such as increased bleeding from high aspirin use. In order to verify whether low doses can also be protective, the researches looked into four trials in Britain and Sweden, conducted in the 1980s or early 1990s, on the cardiovascular impacts of aspirin. They checked the centralised data banks to see whether volunteers in these trials had since died or had been diagnosed with colorectal cancer. On average, the trials lasted six years, entailing volunteers who took either aspirin or a dummy look-alike pill called a placebo. The doses ranged up to 1,200 mg. It was found that out of 14,033 patients whose health could be traced 18 years or so since the trial, 391 had colorectal cancer. Taking aspirin reduced the risk of cancer by 24% and the risk of dying from it by 35%. Interestingly, consistent results were seen across all four trials and there was no increase in benefits beyond a dose of 75 mg. Where the reduction was most remarkable was in cases of proximal colon cancer. These occur in the upper colon and are thus liable to be missed in lower-intestine scans for polyps, the precursor of tumours. The authors say their study had limits, as the original trials were not designed to look at aspects of colorectal cancer, nor was data available for any deaths from aspirin’s side effects. Also, aspirin’s benefit may have been somewhat over-estimated, they said. This was because the original trials took place before colon screening for polyps became a routine practice in those countries. Even so, the evidence has now swung the scales in favour of low-dosage aspirin for a disease that claims 600,000 deaths worldwide each year, they said. “Our findings suggest that long-term low-dose aspirin treatment and sigmoidoscopy screening would combine to substantially reduce cancer incidence in all parts of the colon and rectum,” said the lead author, Peter Rothwell, a professor at the Department of Clinical Neurology at Oxford University. In a commentary, doctors Robert Benamouzig and Bernard Uzzan of the Avicenne Hospital in Bobigny, on the outskirts of Paris, said the study should unleash “the next logical step,” of formulating guidelines for people at risk. Colorectal cancer is the second commonest cancer in developed countries, with a lifetime risk of 5%, according to figures cited in the city. Aspirin is believed to have a preventive effect because it inhibits an enzyme called COX-2, which promotes cell proliferation in colorectal tumours.