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Exercise 'most proven method' to prevent return of breast cancer

NHS Choices - Behind the Headlines -

"A half hour stroll a day can help women who've survived breast cancer prevent the killer disease returning," The Sun reports.

A review of recent evidence, carried out by Canadian researchers, was prompted by the fact that many women who undergo treatment for breast cancer are eager to make lifestyle changes that may help reduce the risk of the cancer returning. But there is a great deal of often conflicting advice, so it is hard to make an informed decision.

The researchers' review of evidence found that physical activity had the strongest reported effect on reducing the risk of breast cancer recurring and dying from breast cancer.

Following the recommended 150 minutes of moderate to vigorous exercise or 75 minutes of vigorous exercise per week guidance, as well as two to three weekly sessions of strength training, can help reduce the risk of breast cancer returning and death from the disease.

The effects of treatments such as surgery and chemotherapy can take a toll on motivation to exercise. But clinical guidelines recommend a gradual return to regular exercise.

 

Where did the story come from?

The study was carried out by researchers from the Division of medical Oncology and Hematology, Odette Cancer Centre Sunnybrook Health Sciences Centre, Toronto, Canada.

The researchers did not report any funding for the study and declared no competing interests.

The study was published in the peer-reviewed Canadian Medical Association Journal and is open-access meaning it is free to read online.

The Mail Online and The Sun reported the story very similarly, emphasising the importance of exercise in reducing risk of relapse.

Interestingly, the headline of The Sun was very positive, "brisk 30-minute walk a day 'STOPS killer breast cancer returning'," whereas the Mail Online took a much more pessimistic stance, "boozing, weight gain and failing to exercise INCREASES the risk of breast cancer returning".

It should be pointed out that The Sun's headline is not entirely accurate as we only know that exercise reduces the risk and doesn't actually stop it.

The Sun also quotes one of the authors of the study, Dr. Ellen Warner, who cautions that "some breast cancers have aggressive biology and will recur despite the most meticulous lifestyle behavior … Patients should not be made to feel that inadequate lifestyle changes have led to recurrence of their cancer."

 

What kind of research was this?

This was a review of systematic reviews (and related meta-analyses) and primary research, that aimed to summarise the role of lifestyle factors in the prognosis of women who have had breast cancer.

It aimed to identify which lifestyle changes can be recommended to women in addition to breast cancer treatments, to reduce their risk of future recurrence and death.

This type of review is a good way of summarising research in an area, however findings can only be as reliable as the studies included.

There were a variety of study types included, but most were systematic reviews of individual observational studies, so they were unable to account for all confounding factors and therefore reliability might be variable.

In addition, we don't know whether all relevant studies have been included. This means there is potential for selection bias.

 

What evidence on physical activity did they find?
  • A meta-analysis of 22 cohort studies found that physical activity can reduce the risk of deaths caused by breast cancer by around 40% (hazard ratio [HR] 0.59, 95% confidence interval [CI] 0.45 to 0.78). This is the biggest effect of any lifestyle factor on breast cancer outcomes.
  • At least 150 minutes per week of physical activity is recommended.

 

What evidence on weight management did they find?
  • Weight gain of more than 10% of baseline body weight during or after breast cancer treatment may reduce survival, but the evidence is weak and the result could be due to chance HR 1.17, 95% CI 1.00 to 1.38).
  • Weight gain of less than 10% is not associated with reduced survival.
  • Risk of recurrence of breast cancer may be increased by weight gain, but this is just based on observational studies. Therefore, many other factors could be responsible.
  • Women who are obese or overweight at breast cancer diagnosis have poorer outcomes.
  • It remains unknown whether weight loss has a preventive effect.

 

What evidence on diet did they find?
  • They did not find robust evidence on any diet and risk of recurrence or mortality.
  • Observational studies have not shown any difference between Western-style diets (high in processed grains, processed meats and red meat) and diets high in fruits, vegetables, whole grains and chicken on the rate of breast cancer recurrence.
  • Soy products were not found to increase breast cancer recurrence. There have been claims that, as soy contains phyto-oestrogens (which are similar to the hormone oestrogen), they could stimulate abnormal cell growth. The review actually found soy may reduce cancer risk, although evidence for this is weak.

 

What evidence on smoking did they find?
  • Based on a large observational study of 20,691 women, those who continue to smoke after a breast cancer diagnosis are 72% more likely to die from breast cancer than women who have never smoked (HR 1.72, 95% CI 1.13 to 2.60).
  • There is insufficient evidence on whether quitting smoking after diagnosis has an effect on breast cancer-specific survival, but it will reduce the risk of other cancers, such as lung cancer, and cardiovascular disease such as heart attack and stroke.

 

What evidence on alcohol intake did they find?
  • They could not say whether alcohol consumption affects breast cancer outcomes or not.
  • However, reducing alcohol consumption to one or fewer drinks per day reduces the risk of a new (not recurring) breast cancer.

 

What evidence on vitamin supplementation did they find?
  • Moderate increases in dietary vitamin C or oral supplementation may reduce breast cancer mortality. Randomised controlled trials are needed to confirm this.
  • Most patients would benefit from vitamin D supplementation, at least to optimise bone health.

 

Conclusion

This was a helpful summary of recent research into how lifestyle changes impact on the risk of breast cancer returning, but it does have some limitations.

Researching lifestyle factors separately is always difficult as they tend to clump together, making it difficult to pick apart individual factors. For example, people who are more physically active tend to have a healthier diet and are less likely to drink excessive amounts of alcohol or smoke.

While the researchers say many studies attempt to make adjustments for these confounding factors, it is difficult to know which studies did this and how successful they were. It is also possible that women who did not exercise were unable to because of adverse effects from their breast cancer treatment.

There is also the fact that lifestyle factors were only looked at after breast cancer diagnosis, when lifestyle before diagnosis might have long term effects.

Still, the conclusion that regular exercise appears to be the best option seems reasonable and appropriate. Aside from cancer prevention, regular exercise can also help reduce the risk of other chronic diseases, such as heart disease.

Read more about the benefits of exercise.

Links To The Headlines

Brisk 30-minute walk a day ‘STOPS killer breast cancer returning’. The Sun, February 21 2017

Boozing, weight gain and failing to exercise INCREASES the risk of breast cancer returning, experts say. Mail Online, February 21 2017

Links To Science

Hamer J, Warner E. Lifestyle modifications for patients with breast cancer to improve prognosis and optimize overall health. Canadian Medical Association Journal. Published online February 21 2017

Long-term daily drinking linked to stiffening of the arteries in men

NHS Choices - Behind the Headlines -

"Men who drink more than a pint a day over several years are at greater risk of heart attack or stroke," The Sun reports.

A UK study found men who consistently drank more than the recommended limits had signs of stiffening of the arteries, which has been linked to an increased risk of heart disease.

Researchers used data from more than 3,000 British civil servants to examine the link. Participants reported their alcohol intake over a 20-year period.

Stiffness of the arteries was also measured using a device that looks at how pressure waves move through an artery – the faster the pulse wave moves, the stiffer the arteries.

Men who were frequent heavy drinkers across the follow-up period had stiffer arteries compared with frequent moderate drinkers. There were no significant findings seen for women. The reasons for this are unclear.

While the study cannot prove cause and effect, and stiffening of the arteries can have a range of causes, it does highlight the fact alcohol-related harms can affect anyone.

Frequently drinking more than the recommended limits can damage your health.

Learn more about the official alcohol guidelines.

Where did the story come from?

The study was carried out by researchers from University College London and the University of Cambridge.

Funding was provided by the UK Medical Research Council Alcohol and the European Research Council.

The UK Medical Research Council, the British Heart Foundation and the National Institutes of Health supported the Whitehall II study data collection.

The study was published in the peer-reviewed Journal of the American Heart Association on an open access basis, and it's free to read online.

The UK media got itself into a bit of a muddle about whether the study says drinking more than a pint a day, just a pint a day, or even just half a pint a week is linked to cardiovascular disease.

The research suggests drinking more than a pint a day is linked to cardiovascular disease. Men who consumed more than 112g of ethanol, assumed to be seven pints a week, were assessed as putting themselves at risk.

Many media sources have quoted Dr Darragh O'Neill, the study's lead author, who tried to explain his theory about these findings. "Heavier alcohol intake may activate certain enzymes that would lead to collagen accumulation, which could in turn exacerbate the rate of arterial stiffening." 

What kind of research was this?

This prospective cohort study aimed to evaluate the association between alcohol consumption and arterial stiffness. Arterial stiffness has been linked with increased cardiovascular disease risk.

Data from the Whitehall II cohort study, which included British civil servants, was used to find links and hypothesise.

This type of study is good for finding links, but can't prove cause and effect.

What did the research involve?

The study used data from the Whitehall II cohort study. This is an ongoing study that recruited British civil servants between 1985 and 1988.

Participants reported their alcohol consumption at regular intervals (described in the study as phases) over the following 20 years, up to 2007-09.

They were asked to report the number of glasses of wine, pints of beer or cider, and measures of spirits or liqueur they consumed in the week before each assessment. These values were then converted into ethanol volumes.

Participants' long-term drinking patterns over this follow-up were placed in categories.

Long-term drinker type (grams a week in each phase):

  • stable non-drinker – 0g
  • stable moderate drinker – 1-112g
  • stable heavy drinker – more than 112g
  • unstable moderate drinker – between 1g and 112g over more than half the phases, but more than 0g in phase 9
  • unstable heavy drinker – more than 112g across at least half, but not all, of phases 1-9 and more than 0g in phase 9
  • former drinker – 0g at phase 9, but intake more than 0g at any earlier phase

In 2007-09, participants completed repeat pulse wave velocity assessments. This is a measure of arterial stiffness – as waveforms travel faster through less elastic tissue, the higher the pulse wave velocity, the greater the arterial stiffness.

They also had their recent drinker type categorised at this time as:

  • no recent intake – 0g
  • recent moderate – 1-112g
  • recent heavy – more than 112g

Participants had pulse wave velocity measured again four to five years later in 2012-13.

Statistical modelling was used to investigate the link between the different drinker types and the relationship with arterial stiffness, and how this progressed over time.

The model was adjusted for potential confounders, including socioeconomic status, level of exercise, body mass index, blood pressure and cholesterol.

One-third of the full cohort (3,130 adults) had complete data available for analysis. The majority of the full cohort were male (74%) and white.

There were few current smokers, but the majority did not meet the recommended weekly exercise levels set by the World Health Organization. The researchers excluded people with cardiovascular disease.

What were the basic results?

Pulse wave velocity measurements taken at the start of the study period (2007-09) showed men who had a long-term heavy alcohol intake of more than 112g of ethanol a week had significantly stiffer arteries than those who drank moderately. There were no other significant findings at this time.

Over the following five years, all drinker groups showed some progression in their arterial stiffness.

But only male former drinkers showed significant progression compared with those who consistently had a moderate alcohol intake.

After full adjustment for all confounders, no significant links were seen between any of the drinker categories and arterial stiffness for women. It's not clear why this was the case.

How did the researchers interpret the results?

The researchers concluded that, "This work demonstrates that consistently heavy alcohol consumption is associated with higher cardiovascular risk, especially among males, and also provides new insights into the potential impact of changes in drinking levels over time.

"It discusses the additional insights possible when capturing longitudinal consumption patterns in lieu of reliance on recent intake alone." 

Conclusion

This prospective cohort study aimed to look at the relationship between long-term alcohol patterns and stiffness of the arteries as a potential indicator of cardiovascular health.

The researchers found men who were stable heavy drinkers had stiffer arteries compared with stable moderate drinkers.

Male former drinkers also had increasingly stiffer arteries over the following four to five years compared with consistent moderate drinkers. There were no significant findings seen for women at all.

But this study does have limitations:

  • This type of study is not able to prove drinking causes stiffness of the arteries. While the researchers have attempted to adjust for potential confounders, other factors may be responsible for the findings.
  • The study didn't find any significant links for female participants, but this may be because they were under-represented in the sample, at only 23.6%.
  • Data for alcohol consumption was self-reported, and this is subject to bias.
  • Assumptions were used to calculate the ethanol content within the drinks, but this can vary widely between beers and wine.
  • Although the study looked at stiffness of the arteries as a proxy indicator, it didn't assess whether long-term drinking patterns are associated with actual health outcomes, such as high blood pressure, stroke or heart disease.

We all know drinking more than the recommended allowance can damage our health.

To reduce health risks from drinking alcohol, the government advises men and women to not regularly drink more than 14 units a week. If you're drinking this many units, it's better to spread them out over three or more days.

Heavy drinking sessions are known to increase your risk of long-term illnesses, including certain cancers, and also increase your risk of accidents.

Read more about the risks of drinking too much.

Links To The Headlines

Drinking more than a pint a day 'puts men at higher risk of heart attack or stroke'. The Sun, February 21 2017

Just half a pint a week could increase risk of heart disease in men. Daily Mirror, February 20 2017

How just one pint a day can increase the risk of heart disease by prematurely ageing the arteries. Mail Online, February 21 2017

Just half a pint of beer a week increases risk of heart disease - new study. The Daily Telegraph, February 21 2017

Links To Science

O'Neill D, Britton A, Brunner EJ, Bell S. Twenty‐Five‐Year Alcohol Consumption Trajectories and Their Association With Arterial Aging: A Prospective Cohort Study. Journal of the American Heart Association. Published online February 20 2017

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