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NCRI conference session: physical activity, obesity and survivorship

by Helen George | Analysis

13 November 2012

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The evidence on physical activity and cancer were discussed

As regular readers will know, we were at the annual National Cancer Research Institute (NCRI) conference in Liverpool last week.

We blogged daily updates from the conference (here’s day one, day two, day three and day four), but a couple of the sessions merited a deeper look. So here’s a write-up from a session that may resonate with many of our readers – the effects of exercise and body weight in people who have had cancer.

Although it’s certainly not a cast-iron guarantee against developing the disease, a healthy lifestyle can help to prevent cancer – the latest estimates suggest that more than four in ten cases could be prevented through lifestyle changes.

But the effects of keeping a healthy lifestyle are less well studied among people who already have the disease. The NCRI session looked at the latest evidence, and what it means.

Healthy environments

The University of Dundee’s Professor Annie Anderson, who chaired the session, kicked off by looking at the bigger picture on lifestyle. She stressed that tobacco remains the largest avoidable risk factor for cancer. No session on this topic would be complete without a mention of smoking.

But excess weight and obesity is another major public health concern, and is one of the most important risk factor for cancer in non-smokers. And it was this, together with physical activity, which was the main focus of the session.

Anderson set the scene nicely by saying how important it is to influence the environment in which we live to help encourage positive lifestyle changes, as well as carrying out interventions at the community and individual level. On a practical level, that means more open spaces for exercise and fewer ads promoting super-sized meal deals, and so on.

And she stressed that this area of work is not just relevant to cancer but to many other diseases, including heart disease and diabetes.

Quality of life and exercise

Moving onto the session’s focus, the panel highlighted that there are two million cancer survivors in the UK and more than 27 million worldwide. As we become better at treating, controlling and curing cancer, we must in turn find ways to improve the quality of life among survivors.

The challenge with this field is that most of the evidence to date is based on ‘observational’ studies and there haven’t been many high-quality (randomised controlled) trials. But still, some lifestyle guidelines are already being issued for cancer survivors, if not to improve their chances of directly beating the disease, then to improve overall health and well-being.

Speaker Professor Wendy Demark-Wahnefried from the University of Alabama reviewed these guidelines (including these from the World Cancer Research Fund) and presented the evidence behind them. The take home messages? There is a likely benefit of physical activity in helping to tackle depression and fatigue (more on this below), and of maintaining a healthy body weight to lower the chances of developing cancer again.

For example, for breast cancer survivors, she cited a 15 per cent increase in risk of a second cancer in the breast in those who are overweight or obese, relative to those who have a healthy weight.

The solution? Physical activity rather than dieting, she argues. Her research published in 2001 looked at pre-menopausal breast cancer patients receiving chemotherapy. The study suggested that lower levels of physical activity – rather than higher energy intake – is usually responsible for weight gain.

Her study also showed that the weight these women gained was associated with an increase in fat but a loss in ‘lean body mass’ (i.e. everything else except fat – so muscles, bones and so on) – characteristic of a lack of exercise. This is different from how people tend to usually put on weight where the excess weight is due to both extra fat mass and lean body mass. This shows why it’s so important to scratch beneath the surface of an observation to understand what is happening – and to use this knowledge to help people.

Dutch researcher Professor Johannes Brug then talked about his work to establish whether exercise can help with rehabilitation for cancer, including tackling fatigue – a problem that he says affects 50-90 per cent of patients. Doctors used to recommend that recovering patients get extra rest, but this can have the opposite affect by reducing their levels of fitness. Instead, moderate physical activity, where appropriate, can break the cycle and help patients feel better and have more energy.

So what next? A study called POLARIS is currently underway to bring together all of the data from studies across the world on physical activity and other interventions and the quality of life of cancer patients. This should help determine what rehabilitation and supportive care programme works best for whom, and under what circumstances.

Personalised advice

Linked to this, we were all humbly reminded of the need for personalised advice and support when a patient advocate in the audience spoke of her experience of cancer, and of how she had wanted to adopt good advice but her walking was limited due to lymphoedema caused by her treatment.

As one speaker subsequently said “There is no such thing as an average patient. We can’t just look at data at the population level – we need personalised recommendations.”

And that was the key message – although studies can guide the way forward, every patient with cancer is unique, and their care should be tailored to their individual circumstances. We can’t take a one-size fits all approach.