Low dose of aspirin reduces occurrence of several common cancers: Study

London School of Hygiene & Tropical MedicineDec 7 2010

Benefit unrelated to dose, gender or smoking - but increases with age

The London School of Hygiene & Tropical Medicine (LSHTM) has contributed to a study showing that a low dose of aspirin reduces the occurrence of several common cancers. The study is published in today's Lancet.

The work was started and carried out by Professor Peter Rothwell in Oxford, and is based on an overview of several randomised trials of aspirin. These have been primarily concerned with reducing heart attacks, but have also gathered information on deaths from cancer.

The trial contributing most information to the overview has been the Thrombosis Prevention Trial (funded jointly by the Medical Research Council and the British Heart Foundation) which was carried out by Tom Meade when he was with the Medical Research Council. Professor Meade is now Emeritus Professor of Epidemiology in LSHTM's Department of Non-Communicable Disease Epidemiology.

As well as confirming that low dose aspirin reduces large bowel cancer cases reported in another recent study also led by Professor Rothwell and to which Professor Meade contributed, it also reduces total deaths due to cancer because it affects several common individual cancers, such as those of the oesophagus (gullet), lung, stomach, pancreas and possibly the brain. Reductions in deaths are around 20-30%.

Benefit is unrelated to aspirin dose from 75mg upwards, gender or smoking habit but increases with age. Aspirin may need to be taken for at least five years before it confers benefit, probably longer for some cancers, but benefit is generally greater the longer aspirin has been taken.

Hitherto, advice about aspirin has been mainly concerned with reducing heart attacks and strokes in those who have already had them. Caution should be exercised by those who are so far free of these conditions because, unless a person's risk of them is very high, the benefit may be outweighed by the risk of serious bleeding. 

Professor Meade says: 'These are very exciting and potentially important findings. They are likely to alter clinical and public health advice about low dose aspirin because the balance between benefit and bleeding has probably been altered towards using it', although Professor Meade adds that this does not mean everyone should automatically take aspirin. Health professionals and others will now have to consider the practical implications.