NCRI 2015

Uptake of exercise is beneficial to cancer patients

Prof Robert Thomas - Bedford and Addenbrooke's Cambridge University NHS Trusts, UK

I’m chairing a parallel session this afternoon entitled Physical Activity: The Panacea. So obviously it’s about physical activity and cancer and how it can improve the wellbeing of patients and there’s some data coming through that it actually improves outcome. We have speakers from around the world describing well-conducted clinical trials, such as Stacey Kenfield from California, who show very clearly and eloquently that if you can motivate patients to exercise up to three to four hours a week there will be considerable benefits for them and for the health service in general.

What’s really happening when we exercise in terms of the physical and mental changes we experience?

Part of the talk this afternoon in the NCRI conference is to look at the biological pathways which change after physical activity. You’re right, there are indirect and direct effects of physical activity. The indirect effects would be, of course, you lose weight and therefore your oestrogen drops and chemicals such as leptin drop and they’re good for the cancer physiology. You could argue that you go out in the sun and your vitamin D levels go up. You just mentioned mood, yes, we know that exercise improves your mood and there are data to show that, for example, if you’re depressed after prostate cancer you have an inferior survival. So that’s the indirect effects. But there are lots of direct effects. So we know, for example, if you exercise your insulin-like growth factor levels drop and your insulin-like growth factor binding protein increases. IGF, if you add it to cells in a petri dish encourages them to grow and proliferate and not commit apoptosis etc. And there are lots of data to show that the drop in IGF levels correlates to an improved survival. So we know that’s a real chemical phenomenon which happens.

But there are other chemicals. We know that prostaglandin levels drop, leptin, which is produced in fat cells, reduces and, again, these all have pro-cancer properties. Leptin levels, although they’re made in cancer cells, it’s not just that you get slimmer, exercise directly reduces leptin levels. There is a neurotransmitter called orexin which when you exercise this is secreted by muscles. We know that this chemical slows cancer growth, it stops cancers metastasising and invading other organs so it’s almost too good to be true. A few years ago there was a bit of a controversy that maybe the analysis of orexin in the bloodstream was inappropriate but more recently it’s been confirmed with mass spectrometry that there is a genuine chemical called orexin and it does go up when you exercise. I could go on and on and on. There are probably about 180 things which happen in our body which improve the environment for us and decrease the environment for the cancer cells.

What conclusions do you draw in your session?

My part of the session is to look at the general overview of the data but there are two preferred papers as well. The conclusions from one of them, which was quite disappointing, is that only 11% of our patients currently exercise to any degree of effectiveness to kick in the anti-cancer properties. When we compare that to a study from three or four years ago it was about the same level. So one of the conclusions that we’re getting lots of evidence coming through that it’s beneficial but we’re failing to encourage people to exercise. This is a universally available strategy which is under-resourced. It’s great that the NCRI has got this session because it’s highlighting the importance but it’s also highlighting the need to do more for our patients.

Are there difficulties in telling a cancer patient who doesn’t have a history of being physically active that they must exercise?

That’s true. You may have a patient who has never exercised so it’s alien advice for him but, as you said, they’ve got fatigue, hot flushes, joint pains and then on top of that you’re advising exercise, they look at you and think you’re maybe an uncaring doctor by even suggesting it. So that’s perhaps why some doctors don’t suggest it to the patients.

But one of the papers we’re presenting this afternoon is looking at how we can speak to patients. For example, most of the literature tells people that exercise is healthy. Well one of the papers showed quite clearly that the patients already know it’s healthy, it’s a bit like smokers, they already know smoking is unhealthy but it doesn’t change their habits. So one of the things we found out is that the patients are afraid to exercise because they think that their fatigue is going to get worse, their joint pains are going to get worse. So it’s almost an education point for healthcare professionals to say you need to change the way you speak to people. So that’s one thing, also there are some data looking at behavioural change interviewing. Instead of preaching to patients that they must do this and that it’s more of an encouragement and almost comes out as their idea, it’s a good idea. So there is that.

But also addressing their toxicities clearer. For example, we know that 55% of patients with cancer have arthritis or we induce arthritis through aromatase inhibitors or biological agents. A lot of the mainstream treatments are not that effective, non-steroidals and so forth which they don’t like taking because of indigestion etc. What we’re doing in our research group is looking at self-help strategies which help symptoms which then would allow them to exercise. So we’re taking a step back. For example, we know that polyphenol rich foods such as broccoli, turmeric, pomegranate, green tea, which we had in a previous supplement which I was on this programme two years ago, we also know from data published by Arthritis Research that those polyphenols protect joints. You can either put those in a supplement or maybe encourage patients to eat more of those foods. Either way that is very rarely discussed with patients. So we’re actually exploring nutritional avenues to protect the joints which will then allow them to exercise. So it’s almost a self-fulfilling prophecy. Considering it’s such an important issue, for example arthritis is so common and exercise is so under-resourced, it’s almost surprising that more research is not done in this field. You could argue the reasons for that but at least we’re now beginning to start studies in this field and other people like Stacy Kenfield from California and the other speakers this afternoon.