Does exercise help if you have cancer? Here’s what we know

Exercise is a wonder drug. It’s a miracle cure. It’s a panacea. If it was a drug, doctors would be prescribing it by the skip load! I’ve heard this so many times from various high-profile talking heads. The problem is it’s not really true.

If we are going to untangle the fact from fiction, we need to go way, way back. Plato knew that exercise was good for you. A quote that is attributed to him goes something like this:

‘Lack of activity destroys the good condition of every human being while movement and methodical physical exercise save it and preserve it.’

All this without having a clue what a clinical trial was. How on earth did he do this? Of course it’s not hard to work out that being more physically active will do you some good.

We’ve all at one time in our lives had a bit of a spurt where we exercised regularly. We all probably felt better about ourselves.

At the same time, we probably didn’t appreciate the panoply of beneficial physiological changes happening in tandem. Everything from improved vascular and cardiac function, neurological enhancements, better metabolic control of things like blood sugar, healthier fat metabolism and distribution around our bodies as well as stronger bones. So why isn’t exercise a miracle cure?

Well, let’s start with cardiovascular disease. There is plenty of evidence that, post-diagnosis, exercise is helpful. If you’re more physically active, for instance by doing cardiac rehabilitation, you can reduce your risk of dying of the disease by about 25 per cent. Decent, but no miracle cure.

From a personal perspective, my family history is like a brutal origin story of cardiovascular disease. I bet one day I might well have to give cardiac rehab a shot. And at that point, I’ll be very grateful indeed for it. But I won’t be expecting to live to 300 years old and to look like Conor McGregor all the while.

This 25 per cent better survival in relation to cardiovascular disease comes from randomised controlled trials of studies looking at these specific interventions and these specific outcomes. That’s key. Randomised trials offer our highest level of evidence. With regards to the question ‘can exercise stop or reduce the speed of cancer progression?’ we really don’t have anything like this right now.

However, efforts are underway to start to gather these data. In the UK, I am leading a study to test if exercise could be a novel primary therapy for men with localised prostate cancer.

These men would ordinarily be on something called surveillance (no active intervention), so it seems like a good place to start to see if it’s appropriate to intervene.

We are asking men to do two and a half hours of exercise a week and we are tracking everything with supervised exercise sessions and heart rate monitors, so we know what dose elicits a beneficial response, if one is there. (That’s another point: robust science isn’t about finding an effect. It’s about robustly testing to see if there is one there at all.)

In the meantime, I am happy to report that there is good evidence from randomised trials that things like combined exercise training with aerobic and resistance work can improve cancer-specific quality of life, reduce cancer-specific fatigue and boost functional capacity.

These might not sound as appealing as ‘longer survival’, but if you have late-stage cancer and you are beset by the horrific experience of chemotherapy and medical castration, improving your quality of life is a huge deal. So there’s that.

A decade ago the prevailing thinking for cancer patients was that ‘rest is best’. This is now known to be rubbish.

But for evidence about the benefits of a specific dose of exercise we have to wait. Our trial is in ‘phase II’, which means we have another few years go to. But then, once it’s done, we’ll have high-quality evidence. Whichever way it goes, there’ll be something to say into the microphone.

Dr Liam Bourke is principal research fellow at Sheffield Hallam University