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Updated: 3 hours 58 min ago

Fit middle-aged men have lower cancer risk

Fri, 2015-03-27 06:00

"Very fit men in their late 40s are less likely to get lung cancer and colorectal cancer than unfit men," says BBC News as it reports on a new US study.

The study involved a comprehensive fitness test of 13,949 US men. They were split into three fitness groups: lowest 20%, middle 40% and top 40%, and followed for an average of 6.5 years to see if fitness affected their chance of developing certain cancers.

Men in the fittest group were 55% less likely to develop lung cancer and 46% less likely to develop colorectal cancer compared with men in the lowest fitness group.

Perhaps surprisingly, men in the top group actually had a 22% higher risk of prostate cancer.

One obvious point is that men who exercise to stay fit are usually healthy in other ways too, such as eating a healthy diet and abstaining from alcohol. This could have influenced the results.

Still, there is evidence that exercise alone can reduce your cancer risk. Information provided by Cancer Research UK explains how exercise can reduce inflammation and prevent bowel damage, which may reduce cancer risk.

With its proven effect of preventing heart disease, regular exercise is always a good idea, whatever your age or sex. Read more about the benefits of exercise

Where did the story come from?

The study was carried out by researchers from the University of Vermont, the University of Texas Southwestern Medical Center, Duke University Medical Center in Dallas, and the Memorial Sloan Kettering Cancer Center in New York.

It was funded by the US National Institute of General Medical Sciences, the National Institutes of Health, and the National Cancer Institute.

The study was published in the peer-reviewed science journal JAMA Oncology. It was published as an open-access article, meaning it is free to read and download online.

Generally, the UK media reported the story accurately, but none mentioned the possibility that diet could be accounting for some of the improvements seen, not just fitness.

What kind of research was this?

This was a longitudinal study looking at whether cardiorespiratory fitness (having both a healthy heart and lungs) prevents or improves outcomes in cancer.

It used data already collected as part of the long-running Cooper Center Longitudinal study.

There are many risk factors for cancer, including age, diet and physical activity. This study focused on fitness and whether this helped men develop fewer cancers, and survive better if they did develop cancer.  

What did the research involve?

The research analysed fitness data on 13,949 US men collected as part of the Cooper Center Longitudinal study between 1971 and 2009.

The men were split into three fitness groups: lowest 20%, middle 40% and top 40%, and followed for an average of 6.5 years to see if fitness levels affected their chance of developing lung, colorectal or prostate cancer.

Fitness was assessed using an incremental treadmill test, which tests a person's ability to run to exhaustion.

The outcomes researchers were most interested in studying were:

  • new cases of prostate, lung and colorectal cancer 
  • death from any cause for men developing cancer over the age of 65
  • cause-specific death, such as cardiovascular disease, for men developing cancer over the age of 65

Cancer diagnosis and notification of death came from Medicare claims data, which is the US government health insurance system covering people over 65.

The statistical analysis took account of many common cancer risk factors, but not diet or the stage of cancer at diagnosis.

The confounding factors adjusted for included:

  • age
  • examination year
  • body mass index (BMI)
  • smoking
  • total cholesterol level
  • systolic blood pressure
  • diabetes mellitus
  • fasting glucose level  
What were the basic results?

Over the study period, 181 men were diagnosed with colon cancers, 200 with lung cancers, and 1,310 with prostate cancers.

The main message from the results is that exercise is very good at reducing the risk of developing lung and colorectal cancer, as well as helping reduce the risk of dying from cancer or cardiovascular disease. The pattern of risk for prostate cancer was less clear. 

Men in the fittest group were 55% less likely to develop lung cancer (hazard ratio [HR] 0.45; 95% confidence interval [CI], 0.29 to 0.68), and 46% less likely to develop colorectal cancer (HR, 0.56; 95%; CI, 0.36 to 0.87), compared with men in the lowest fitness group. The risk of prostate cancer was actually 22% higher (HR 1.22; 95%; CI, 1.02 to 1.46).

Similar benefits were seen comparing the middle exercise group with the lowest exercise group, but the risk differences were slightly smaller.

For example, risks were 43% lower for lung cancer and 33% lower for colon cancer compared with the lowest fitness group. This time there was no difference for prostate cancer. This analysis covered cancers diagnosed at any age.

Looking only at cancers diagnosed after the age of 65, the fittest group were 32% less likely to die from cancer compared with men in the lowest fitness group (HR, 0.68; 95%; CI, 0.47 to 0.98) – this included prostate cancer.

They were also 68% less likely to die from cardiovascular disease after a cancer diagnosis (HR, 0.32; 95%; CI, 0.16 to 0.64) compared with the least fit men. 

How did the researchers interpret the results?

The authors concluded that, "There is an inverse association between midlife CRF [cardiorespiratory fitness] and incident lung and colorectal cancer, but not prostate cancer. High midlife CRF is associated with lower risk of cause-specific mortality in those diagnosed as having cancer at Medicare age [over 65]." 

Conclusion

This study shows that cardiovascular fitness is likely to reduce men's chances of developing lung and colorectal cancer, and appears to boost survival from cancer or cardiovascular disease in those diagnosed after the age of 65. This was based on comparing the top 40% of fittest men with the 20% least fit.

The study focused on fitness and took account of major risk factors for cancer, such as smoking and blood pressure. However, it left out one important risk factor: diet. What people eat and drink is known to affect cancer risk.

The fittest group may also have been the healthiest in terms of eating well and drinking alcohol within safe limits. This probably accounted for some of the risk reductions seen in this study. What proportion? We don't know. 

This, in effect, makes this a study of healthiness incorporating fitness and diet. The evidence that eating well and being active reduces the risk of cancer, heart disease, stroke and diabetes is already well established. Studies have also shown regular physical activity also benefits our mental health.

Read more about reducing your cancer risk.

Although fitter men over the age of 65 diagnosed with cancer had better survival rates, there are other unmeasured factors that could have contributed. It is not known whether the fitter people were diagnosed with cancer at an earlier stage, which would have increased their chance of survival.

There was also a counterintuitive finding worth noting. The fittest group were more likely to be diagnosed with prostate cancer than the least fit. This is important, as prostate cancer risk was much higher than lung or colon cancer in the sample.

The study authors thought this might be because fitter men go for more cancer tests in the US than unfit men, so therefore the cancer is discovered and diagnosed more often in that group.

It could also be the case that men in the fittest group would probably live longer, and prostate cancer is an age-related disease.

But we don't know this for sure, and there could be other explanations worth investigating.

Would you know if you had prostate cancer? Read more about prostate cancer symptoms.

Analysis by Bazian. Edited by NHS ChoicesFollow Behind the Headlines on TwitterJoin the Healthy Evidence forum.

Links To The Headlines

Fit middle-aged men 'at lower risk for some cancers'. BBC News, March 27 2015

Keep fit to beat cancer: Looking after yourself in middle age boosts men's chances. Daily Mirror, March 27 2015

Keeping fit helps men with cancer to boost survival chances by a third. The Times, March 27 2015

Links To Science

Lakoski SG, Willis BL, Barlow CE, et al. Midlife Cardiorespiratory Fitness, Incident Cancer, and Survival After Cancer in Men - The Cooper Center Longitudinal Study. JAMA Oncology. Published March 26 2015

Categories: News

Crossing your fingers may help reduce pain

Fri, 2015-03-27 04:00

"Crossing your fingers might reduce pain," says The Guardian. The study behind the news found crossing your fingers may confuse the way your brain processes feelings of hot and cold – and, in some cases, reduce painful sensations.

Rather than subjecting the participants to "normal" pain, the authors used a trick known as the thermal grill illusion. The thermal grill illusion is not the latest in BBQ technology, but an unusual – and well validated – phantom pain effect.

When the skin is subjected to an alternating pattern of harmless coldness followed by heat, it creates a sensation of "burning coldness", but does no damage to the skin. It is something akin to the burning sensation felt by anyone placing cold hands under warm water after a snowball fight.

The researchers applied hot and cold sensations to the ring, middle and index fingers to create phantom pain sensations in volunteers. The phantom pain reduced in some people when they crossed their fingers.

This artificial phantom set-up means the findings probably don't apply to most real-life experiences of pain. Would a woman crossing her fingers during childbirth feel some benefit, or would someone who has just hit their thumb with a hammer? Probably not.

We shouldn't get too hung up on the crossed finger idea, though. The concept behind it is more interesting. The study tentatively showed that pain might be influenced by how our bodies are organised in space and relative inputs from different parts of your body.

If it is found to be a regular and real occurrence through more research, this may have potential for use in pain management in healthcare.

Where did the story come from?

The study was carried out by researchers from University College London (UCL) and the University of Verona (Italy).

It was funded by the CooperInt Program from the University of Verona, the European Union Seventh Framework Programme, the Economic and Social Research Council, and the European Research Council.

The study was published in the peer-reviewed science journal Current Biology.

The Guardian reported the story accurately, making it clear it was not real-world pain, but phantom pain from the thermal grill illusion.

The paper interviewed Elisa Ferrè of UCL and a co-author, who said: "There might be applications for treating people with chronic pain … the position of your limbs or digits is something that would be very easy to manipulate."

Adding a welcome note of caution, The Guardian wrote: "The findings did not establish whether crossing your fingers would be as soothing with a real painful stimulus, rather than an illusory one, but Ferrè said her hunch is that it would help."

What kind of research was this?

This was a study of human volunteers investigating whether pain perception is influenced by the position of their fingers.

Rather than subjecting the participants to conventional pain, the team used a trick known as the thermal grill illusion to create a phantom pain sensation.

Controlled experiments such as these are useful for developing new ideas and testing them in the early stages. But testing pain in an indirect manner like this isn't ideal. It would be more useful to devise a test using actual pain, but this has ethical dimensions to consider.

What did the research involve?

The researchers used three heat pads under the index, middle and ring fingers of participants to test different combinations of the thermal grill illusion, and whether crossing fingers reduced the phantom pain.

Participants also adjusted a temperature delivered to the other hand until it matched their perception of the cold target finger (index or middle).

The thermal grill illusion works by applying a warm sensation to the index and ring fingers, and a cold sensation to the middle finger. The grill-like pattern of warm-cold-warm creates a burning sensation in the middle finger, even though it is in fact exposed to cold.

About half of people go as far as describing the feeling as painful. The sensation is much more intense than the hot or cold on their own.

According to the researchers, the illusion might work because the hot sensation in the outer two fingers blocks the activity in a certain cooling receptor under the skin. With this pathway blocked, the hot signals from the nearby hot areas are felt more intensely.

What were the basic results?

The study found significant temperature overestimation when the target finger was in the middle (warm-cold-warm) compared with on the end (cold-warm-warm).

The effect depended on the target finger being in the middle of thermal inputs, but it didn't matter whether this was the index or middle target fingers.

The thermal grill effect for the middle finger was abolished when it was crossed over the index. The same effect was generated for the index finger when it was crossed with the middle.

How did the researchers interpret the results?

The team concluded that, "Our results suggest that the locations of multiple stimuli are remapped into external space as a group; nociceptively mediated sensations [pain perception] depended not on the body posture, but rather on the external spatial configuration formed by the pattern of thermal stimuli in each posture."

Conclusion

This study investigated pain using a thermal grill trick, which applies hot and cold in different combinations to the index, middle and ring fingers to induce a phantom burning sensation.

This showed that crossing your fingers may confuse the way your brain processes feelings of hot and cold, and in some cases stopped the phantom pain.

The biggest limitation of this study is that it looked at phantom pain using the thermal grill trick, rather than actual pain. Phantom pain may be different from "normal" pain, so the results may not relate to a regular pain situation.

We shouldn't get too hung up on the crossed finger idea, though. The concept behind it is more interesting. The study tentatively showed that pain might be influenced by how our bodies are organised in space, and relative inputs from different parts of your body.

If found to be a regular and real occurrence through more research, this may have potential for use in pain management in healthcare.

For example, The Guardian says: "Scientists believe the phenomenon could ultimately be harnessed to help treat chronic pain patients, who suffer from painful sensations, often long after a physical injury has healed."

At present, this is largely speculative. The study only showed reduction in phantom pain, and only under a very specific and artificial set of circumstances. Research that is more relevant and applicable to real life would be the logical next step for this research field. 

Still, how we think about pain can sometimes alter how it much it affects us. Many people find cognitive behavioural therapy (CBT) techniques can be useful in helping people cope better with chronic pain.

Read more about coping with pain.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

Links To The Headlines

Crossing your fingers might reduce pain, says study. The Guardian, March 26 2015

Crossing your fingers actually DOES help – just not the way you expect. Metro, March 26 2015

Links To Science

Marotta A, Ferrè ER, Haggard P. Transforming the Thermal Grill Effect by Crossing the Fingers. Current Biology. Published online March 26 2015

Categories: News

Do antibiotics in pregnancy cause cerebral palsy and epilepsy?

Thu, 2015-03-26 05:00

"Antibiotic used in pregnancy linked to risk of epilepsy and cerebral palsy," The Guardian reports.

The results of a new study suggest women who take macrolide antibiotics were slightly more likely to give birth to a child with one (or both) of these conditions, compared with women who take penicillin.

But no association was found between taking antibiotics in general during pregnancy and cerebral palsy (a condition that causes movement disorders) or epilepsy (a condition that causes seizures).

However, a direct comparison between these groups of women is not entirely reliable. There could be other confounding factors that could account for the difference seen, such as the type and severity of infection.

The study does not prove that macrolides cause either cerebral palsy or epilepsy. It is possible an underlying infection in pregnancy increased the risk of these conditions, rather than the treatment itself.

There is no such thing as an entirely 100% risk-free medical intervention. This means we need to use the best evidence available to make an informed decision about the trade-off between the benefits and risks of various choices.

Most experts would agree that the benefits of treating bacterial infections in pregnancy far outweigh the potential risks of antibiotics – if infections are left untreated, it could result in the infection being passed on to the baby, or most seriously, miscarriage or stillbirth

Where did the story come from?

The study was carried out by researchers from University College London and the Farr Institute of Health Informatics Research, London, and was funded by the Medical Research Council.

It was published in the peer-reviewed journal PLOS One on an open-access basis, so it is free to read online.

The Guardian, The Daily Telegraph and the Mail Online's reporting was accurate and responsible. All three papers pointed out that the increased risk from macrolides found in the study was small and could be explained by other factors (confounders).

The papers also included advice from experts that women should continue to take antibiotics prescribed for infection.

It is a shame, then, that all three papers chose to run with alarmist headlines that failed to put the increase in risk into any useful context.

The papers also singled out a common antibiotic called erythromycin. This belongs to the group called macrolides, but it was not focused on by the study.

What kind of research was this?

This was a retrospective cohort study involving 195,909 women. It looked at whether antibiotics prescribed during pregnancy were linked to a higher risk of cerebral palsy or epilepsy in their children.

Cohort studies are often used to look at whether particular events are linked to certain health outcomes. The advantage with this type of study is that it can follow large groups of people over long periods of time, but they cannot prove cause and effect.

Retrospective cohort studies, which look back over time, may also be less reliable than those that follow people in time, called prospective cohort studies.

The authors say antibiotics are one of the most frequently prescribed drugs during pregnancy.

However, they say one large randomised controlled trial (RCT) found certain antibiotics given to women who had gone into premature labour were associated with an increased risk of cerebral palsy or epilepsy in their children at seven years of age.

The two antibiotics used in this previous trial were erythromycin, a macrolide, and co-amoxiclav, which is a type of penicillin.

What did the research involve?

The researchers used data on 195,909 women who had registered at their GP surgeries before pregnancy and had a baby born at or after term (37 weeks).

For women with multiple pregnancies (about one-quarter of the cohort), one pregnancy was selected randomly for analysis. Women whose children were born preterm were excluded because premature babies already have an increased risk of cerebral palsy and epilepsy.

They looked at whether the women had been treated with any oral antibiotics during pregnancy, and, if so, which class of antibiotics, the number of courses they had, and the timing of treatment during pregnancy.

The women's children were followed until seven years of age for any diagnosis of cerebral palsy or epilepsy, as recorded in the children's primary care records.

The researchers analysed the data using standard statistical methods. They adjusted their results for a wide range of maternal risk factors.

These included maternal age at delivery; pregnancy complications; chronic conditions such as obesity; treatment for chronic medical conditions during pregnancy; tobacco and alcohol use; social deprivation; and maternal infections that could potentially cause damage to the foetal brain.

What were the basic results?

A total of 64,623 (33.0%) of the women were prescribed antibiotics in pregnancy, and 1,170 (0.60%) children had records indicating they had cerebral palsy or epilepsy, or both.

Once the researchers adjusted their results for confounders, they found:

  • no association between antibiotics and cerebral palsy or epilepsy (hazard ratio [HR] 1.04, 95% confidence interval [CI] 0.91-1.19)
  • compared with penicillins, macrolide antibiotics were associated with a 78% increased risk of cerebral palsy or epilepsy (HR 1.78, 95% CI 1.18-2.69; number needed to harm 153, 95% CI 71-671)
  • children whose mothers received more than three antibiotic prescriptions during pregnancy had a 40% increased risk (HR 1.40; 95% CI 1.07-1.83) compared with those with no prescriptions
How did the researchers interpret the results?

The researchers say that their findings indicate the prescribing of macrolides in pregnancy is linked to an increased risk of cerebral palsy or epilepsy in childhood.

They speculated about why macrolides might be associated with harm – arguing, for example, that if women stopped taking the drugs because of side effects, the partially treated infection might prolong the foetal brain's exposure to inflammation.

However, they add that there is growing evidence that taking macrolides during pregnancy is associated with harm, and these drugs may have specific adverse effects on the foetus.

Conclusion

The findings from this large study indicate that antibiotic use in pregnancy was not associated with an increased risk of cerebral palsy or epilepsy. The apparent increased risk of macrolides compared with penicillin is not reliable.

A direct comparison between the women taking each type of antibiotic is inaccurate, as it does not take into account potential confounding factors. These include:

  • the type and severity of the infections, which could have affected the baby, rather than the antibiotic
  • whether the women took all of the course of antibiotic or not as a result of side effects; if stopped early, the infection may not have been fully cleared and could have then harmed the baby
  • other unmeasured maternal factors that influenced the type of antibiotic the women were given, such as other medications or health conditions

Additionally, the analysis for macrolides was based on small numbers of women, so the results could also have occurred by chance. It is important to stress that the risk to individual pregnancies is small.

Doctors will only prescribe antibiotics in pregnancy if they think there is a clear clinical need, where mother and baby are potentially at threat. Any risk to your pregnancy posed by antibiotics will probably be far outweighed by the benefits of treatment.

Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.

Links To The Headlines

Antibiotic used in pregnancy linked to risk of epilepsy and cerebral palsy. The Guardian, March 25 2015

Antibiotic pills 'can hurt unborn baby': Common drug linked to cerebral palsy and epilepsy. Mail Online, March 26 2015

Common antibiotic may double the risk of epilepsy or cerebral palsy in unborn babies. The Daily Telegraph, March 26 2015

Links To Science

Meeraus WH, Petersen I, Gilbert R. Association between Antibiotic Prescribing in Pregnancy and Cerebral Palsy or Epilepsy in Children Born at Term: A Cohort Study Using The Health Improvement Network. PLOS One. Published online March 25 2015

Categories: News