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Aspirin Cuts Cancer Risk - A Reality Check


The headlines that aspirin cuts your risk of getting cancer by a third look wonderful, but let's have a reality check on what this means in real life.

Aspirin Reduces Cancer - The Story So Far

Since the 1900's, some studies have shown that aspirin reduces the risk of some cancers, especially bowel cancer, Other drugs related to aspirin, such as NSAIDs (Non Steroid Anti-Inflammatory Drugs such as ibuprofen) have been shown to have a much worse side-effect profile than aspirin, and so have not been proposed as anti-cancer agents. However, the research was inconclusive and contradictory, and so there were no guidelines within the NHS about whether aspirin should be recommended to patients as a cancer preventative.

Headlines - 'Aspirin Cuts Cancer Deaths By A Third'

The study published in the Lancet on the 7th December 2010 by Peter Rothwell created a lot of media interest and headlines such as 'Aspirin Cuts Cancer Deaths By A Third' appeared everywhere. Customers began ordering low dose aspirin to cut down their risk of getting cancer. Let's just slow down for a moment and take a reality check. Whenever there seems to be a quick fix for something, it's worth examining the small print, as real science isn't easily reduced to a simple headline, and quick fixes don't usually work.

The study is based on looking back on the records of 8 previously published drug trials involving 25,570 patients given 75mg aspirin daily for a period of about 5 years. This looks promising as it is based on a large number of people. However, these were people who were involved in drug trials about heart disease, not about cancer, and they all had higher risk factors for heart disease to start with. Not your average population then. They were mainly middle-aged men who were selected as having no medical problems with taking aspirin. So, not many women, and no healthy people then. OK, this starts to look a bit more limited. Bear in mind that the results of any trial can only be regarded as true for the population that was studied.

Cancers are slow to develop, so the study followed up patients for 20 years. This is good. If you are diagnosed with cancer now, then this started many years ago and has been slowly growing ever since. The results showed that the most benefit was in taking a low dose 75mg aspirin between the ages of 45 and 70 for at least 5 years. This benefit lasted for 20 years (the length of the study data) and for 1,000 people recruited to the study, 30 died from cancer without aspirin, and 25 with it. The benefit increased with age, starting at age 45, when many cancers would be starting, and continuing to the age of 70, when most cancers would have been prevented but the risk of stomach bleeding or stroke increases significantly. This saves 5 lives. Most impressive.

The reduction in deaths showed -

  • Prostate Cancer - Down 10%
  • Lung Cancer - Down 30%
  • Bowel Cancer - Down 40%
  • Oesophageal Cancer - Down 60%

These results are promising but not conclusive, but they may not be easy to follow up with new studies, as there are serious ethical considerations about doing this research as a trial for cancer, as the proven benefits of aspirin and heart health have to be taken into account before any trial can be approved. However, taking aspirin for longer than the typical 5 years would appear to offer greater benefit in reducing cancer than the trial results show. This would be even more significant.

Further studies by Peter Rothwell, published in the Lancet in March 2012 extended his analyis from 8 to 51 trials, and confirmed the results of his earlier publication with a reduction in cancer over a 3 year period with higher doses of aspirin of 300mg, or more a day, and over 5 years with a low 75mg daily dose. This effect was just as marked with people over 60 as with those of middle age. (Reference 8). A second paper published in the same month in The Lancet Oncology also shows a long-term reduction over a 20 year period in the incidence of cancers, and a reduction of about 50% in cancers spreading throughout the body (metastasis) with aspirin use. No drug has been shown to reduce metastasis before this trial. (Reference 9).

The Dangers Of Taking Aspirin

Anyone thinking of taking aspirin to lower their risk of getting cancer, should bear in mind that aspirin, even in low doses, can cause side effects, which can be serious, and even fatal. Here are the main points to consider -

  • Aspirin can cause stomach bleeding. The risk affects about one person in a thousand taking aspirin, of which about 5% are fatal, but many more are medical emergencies. Taking aspirin after food or milk may help to reduce this, but probably not by much.

  • Aspirin thins the blood, and this increases the probability of bleeding in the brain, resulting in hemorrhagic stroke. The incidence is about one event in a thousand years of use, but this one event can cause permanent disability or death.

  • Aspirin interacts with many drugs and affects many medical conditions. Check with your doctor or pharmacist if you have any medical problems or are taking any other drugs before taking aspirin.

  • The risk of serious side effects from aspirin increases with age, especially for the over  75's, where daily aspirin is considered to be a major factor in causing stroke, a serious cause of disability and death..

Our advice is to check with your doctor before taking low dose aspirin on a regular basis. Your doctor needs to know what you are doing and will weigh up the benefits against the risks of taking low dose aspirin on a regular basis to prevent cancer, for you as an individual. We will not approve the sale of low dose aspirin if you have not discussed this with your doctor.

Aspirin 75mg is a low dose aspirin tablet which can to help mininise the chance of further heart attacks or strokes, taken after consultation with your doctor

The Real Story Behind The Headlines

Salicylates like aspirin also occur naturally in fruit and vegetables. All salicylates break down in the body to salicylic acid, and anyone eating a diet rich in the recommended amounts of fruit and veg already has a significant amount of salicylic acid in their blood. It is already known that vegetarians have lower rates of cancer and higher salicylate levels in their bodies. These levels are already equivalent to taking a low dose aspirin each day. Natural salicylates in the diet are highest in organic fruits and vegetables grown naturally. Intensively farmed, or cossetted plants without natural stress don't produce so much. Salicylates are also present in many herbs and spices.

This could be one explanation of why a diet high in fruit and vegetable cut your cancer risk. Unfortunately, nobody want to hear any more about this and the chance of just popping a pill has greater appeal, as well as making a better headline. The salicylates in fruit and vegetables may in fact play a bigger role in protecting against cancer than was previously realised, as much of the research has focused on the antioxidants content of fruit and veg preventing cancer.

So How Can You Reduce Your Chance Of Getting Cancer?

Remember that  about 80% of cancers are caused by lifestyle factors within your control. This is where you control your cancer risk by proving a body environment where cancer does not grow and thrive.Prevention is the way forward in reducing cancer, because treating cancer once it appears has only limited success, despite billions of pounds being spend on treatments. (See Losing The War On Cancer).

Currently it is not recommended to take a daily dose of aspirin to lower this risk because there can be serious, even fatal side effects to doing this.

However there are other things you can do to minimise your risk of cancer, such as:


Colin Winstanley (SuperLiving's Pharmacist)


  1. Effect of daily aspirin on long-term risk of death due to cancer: analysis of individual patient data from randomised trials - The Lancet, 7th December 2010
  2. Long-term effect of aspirin on colorectal cancer incidence and mortality: 20-year follow-up of five randomised trials - The Lancet, 20th November 2010
  3. Small daily aspirin dose 'cuts cancer risk ' - BBC News
  4. Aspirin 'prevents bowel cancer' - BBC News
  5. Eureka! Here's how aspirin really can beat cancer - Mail Online
  6. Aspirin a day reduces cancer death risk - FT
  7. Anti-cancer benefits of fruit and veg are underlined - The Independent
  8. Short-term effects of daily aspirin on cancer incidence, mortality, and non-vascular death: analysis of the time course of risks and benefits in 51 randomised controlled trials - The Lancet, 21st March 2012 
  9. Effects of regular aspirin on long-term cancer incidence and metastasis: a systematic comparison of evidence from observational studies versus randomised trials - Lancet Oncology, 21st March 2012
  10. Effect of daily aspirin on risk of cancer metastasis: a study of incident cancers during randomised controlled trials - The Lancet, 21st March 2012

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