Aspirin and cancer prevention
An old professor of medicine used to say that if he had to choose a single medicine to take with him on a desert island, it would be aspirin. This humble and largely untested medicine has been shown to have wonderful therapeutic effects and has been...
An old professor of medicine used to say that if he had to choose a single medicine to take with him on a desert island, it would be aspirin.
This humble and largely untested medicine has been shown to have wonderful therapeutic effects and has been used to treat disorders which include the ubiquitous headache as well as more serious disorders of coagulation.
More recently evidence has emerged suggesting that regular use of aspirin can reduce the incidence of cancer of the colon, one of the most common cancers in the western world.
A relatively low daily dose of aspirin, such as that used for ‘thinning’ the blood, was found to reduce the incidence of cancer of the colon and rectum by a quarter, and perhaps more significantly, reduced deaths from this cause by a third.
This study conducted at John Radcliffe Hospital in Oxford (UK), has now been further confirmed by its authors in an article in the well-regarded medical journal, The Lancet (December 7).
The study, involving 25,570 patients, looked at the long-term effects of daily use of aspirin. It found that the number of deaths in patients taking aspirin was reduced by 21 per cent compared with those who were not taking aspirin.
The longer the period on aspirin, the more significant was the protective effect: after five years, a beneficial effect was already seen in the prevention of several kinds of cancer, but it took about 10 years for significant prevention of stomach and colorectal cancer to become evident, and about 15 years for prostate cancer. In other words, one has to take aspirin for a considerable number of years before the full beneficial effect can become significant.
This study also showed that that aspirin ingestion protected also against various kinds of cancer, including lung, prostate, brain, bladder and kidney cancers, and confirmed the more significant effect of protection against gastro-intestinal cancer. The reduction in risk reduction varied from 60 per cent for oesophageal cancer to 40 per cent for colorectal cancer and 10 per cent for prostate cancer.
But aspirin is no panacea and is not expected to counteract the well-known cancer-producing effects of smoking. The incidence of cigarette-induced lung cancer is not reduced by ingestion of aspirin.
Many elderly patients have been taking low-dose aspirin for a long time with the idea of ‘thinning’ the blood, making it less coagulable, in the hope of preventing clotting and related thrombotic disasters.
On the other hand, one well-known side-effect of aspirin is the increased tendency to bruising, and longer bleeding time after cutting oneself. There is also the potential risk of internal bleeding following knocks, blows and other accidents.
The question now is whether the risks of low-dose, long-term use of aspirin are more than counterbalanced by the beneficial effect of prevention of cancer, which poses a very real threat to the community.
This question is still being actively considered and a definitive answer anxiously looked for.
The results of further trials are expected to be published in the coming year.