As the UK descends into hysteria around petrol and pasties, I have been reflecting for the last week on Peter Rothwell’s recent Lancet papers about cancer prevention and the role of aspirin. Basically, daily low-dose aspirin not only prevents development of new cancer, but also the spread of cancer. Aspirin is one of the oldest drugs in the drug cabinet of hospital wards and GP surgeries, but we continue to discover more about its roles in medicine. As new evidence appears on the horizon, the information and guidelines for practising doctors and their patients still continues to change. There are inevitably time delays in how quickly new information filters through healthcare settings and broader society, and how it is interpreted by both the patient and the doctor.

Aspirin has several different uses which are proven by large bodies of evidence, including as a painkiller, prevention of cardiovascular disease in people at risk (primary prevention) and people with known cardiovascular disease (secondary prevention) and now for prevention of cancer. I always love to refer back to the Hippocratic Oath, and so we have to weigh aspirin’s harms with these many benefits. The main harm with aspirin is bleeding, particularly people who have a tendency towards bleeding anyway, e.g. individuals with history of gastric ulcers.

Interestingly, as the new data is emerging about the long-term preventive effects on cancer, the use of aspirin for two other indications is in decline due to evidence of not that much good when weighed against the risk of bleeding. First, most doctors do not recommend low-dose aspirin for primary prevention of cardiovascular disease, largely due to available data from meta-analyses showing that it does not change mortality in diabetics or non-diabetics. Second, in patients with atrial fibrillation, a heart rhythm problem which increases risk of stroke, aspirin is no longer recommended, yet most guidelinesaround the world still include it. So while we can recommend aspirin for long-term cancer prevention, we may not be able to recommend it in healthy individuals for long-term stroke prevention.

Evidence-based medicine is following a moving target of diseases and treatments and so the evidence is also always changing, even for drugs as old as aspirin. So for newer drugs, you can begin to imagine how little we know. The challenge is to keep all people, both doctors and patients up-to-date with all available evidence and guidelines. However, we know that this is difficult, given that both doctors do not always follow guidelines and people do not generally like to take tablets. Notably, most news reports covering the “aspirin and cancer” story advised people to go and see their doctor before starting the drug. Fergus Walsh, of the BBC, quoted a notable academic, “Doctors were good at treating disease, but when it came to preventing ill-health then people had to make their own judgements”. I agree. I wonder whether people have as much chance of making the “right decision” themselves. And before you ask, I do not take an aspirin a day yet, but I did start cycling to work again this week. One preventive step at a time.

In the BMJ this week is a case control study on Mobile phone base stations and early childhood cancers. A case control study is an epidemiological study design in which persons with and without a disease, in this case cancer, are studied to identify factors (mobile phone masts) associated with the disease. The gold standard would be a prospective study (not a trial as this would be unethical); however, when the disease is rare it is too difficult, costly and would involve following millions of children to detect the cases.

Concerns has been raised due to there being a few clusters of cancers in people living nearby to mobile masts. Participants in a survey were concerned about or attributed adverse health effects to mobile phone base stations and those living within 500 m reported slightly more health complaints than others.

In the present study for two years (1999 to 2001) researchers obtained data on all registered cases of cancer in children aged 0 to 4 in Great Britain. From 1,926 cases, 1,397 (73%) were included. Four controls per case were obtained and matched by sex and date of birth.
Further to this mobile phone operators provided data on antennas to an accuracy of about 10m and the researchers estimated exposure in relation to the distance and the total power output across base stations within 700 m (the typical peak is not nearest the mast, but normally is 200 to 500 m from the base station). They also and used a model to compute power density (dBm) which was validated with data from two further surveys.

The results of the study showed the mean age at diagnosis of cancer was two years and the mean distance at birth from a base station was not different between the cases, 1107 m and the controls, 1073 m (P=0.31). Also there was no difference in terms of the mean total power output of base stations within 700 m (P=0.54) for both groups; and no difference in the mean modelled power density (P=0.41).

The evidence presented in this paper for lack of effect is backed up by the dramatic increase in the use of mobile telephones not giving rise to a subsequent increase in the incidence of brain tumours. The one major limitation of this study is that they were unable to account for movement of the mother during pregnancy, which could have reduced the ability of the study to detect any true excess in risk.

Overall this is a well done study and allows us to feel more certain about the evidence base that there is no association between risk of cancer in young children and exposure to mobile phone base stations. It seems we can all relax a little more about mobile phone masts, the radiofrequency exposures are extremely low and backs up the World Health Organization, view that cancer is unlikely to be caused by cellular phones or their base stations.

If you want ot know a bit more then follow the excellent story tracker.

Today, as people queue at polling booths around the country, I wonder how much they will be influenced by the health policies of the main political parties. You would hope that it has a big bearing on people’s voting choices as the NHS is the UK’s biggest employer with a 1.5 million-strong workforce responsible for the health of 60 million people. Both the Lancet and the BMJ have tried to tease out what the different parties are offering over the last couple of weeks.

A Lancet editorial looks at how the three main parties fare in achieving aims of “better services”, “fairer services”, “protecting health” and “advancing health”. It concludes that the Conservatives and Liberal Democrats lead over Labour in terms of “fairer services” but Labour is likely to deliver better services and is ahead in terms of global health policy. There are many similarities between the health manifestos of the three main parties but the more you analyse, the less detail you find, particularly regarding how the NHS will be funded in difficult economic times and how limited resources will be allocated. This vagueness is there in the manifestos of the smaller parties as well.

There have been many calls to bring evidence to the realm of policy making, but it is difficult to find objective evidence-based statements in the policy documents of three major parties. This lack of evidence means that voter decisions are less likely to be based on facts, and are more likely to be influenced by political spin. For example, it is impossible to escape the political football that is cancer care, kicked from Labour to Conservatives throughout this election campaign, but data about how services will be funded, or how the burden of cancer compares with burden of other diseases in the UK is lacking. There is little or no mention of cost-effectiveness of drugs. This information is available in the public domain, but it is barely ever quoted, and, as far as I can tell, evidence-based medicine is not mentioned in any of the manifestos. Instead we get politicised promises of “an appointment within a week” by Labour versus “access to more cancer drugs” under Conservatives. You can only be an informed voter if there is good quality information from all the political parties.