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This is the transcript of an episode of our podcast, That Cancer Conversation. You can listen to the episode here

Sophie (Host)

Hi and welcome to That Cancer Conversation, the podcast by Cancer Research UK that brings together the science and the stories behind cancer, with me, Sophie Wedekind. 

When thinking about cancer care, our first thoughts may be about surgery or chemotherapy. But what about what we eat? We know that nutrition and diet is incredibly important for health, but cancer can change the relationship we have with food. 

Now we’re not talking about preventive foods. But if you do have any questions about that, or any other topics you want us to explore, you can send us an email at [email protected] and it might be made into a future episode. So make sure you’re subscribed to the show wherever you get your podcasts. 

In this episode, we’re focussing on food and diet after cancer treatment. Cancer can strike up big questions, including ones like ‘what can I eat?’ or even ‘what should I eat?’ 

I sat down with Dr Clare Shaw, a lead cancer dietician and therapy researcher. She has written multiple books with the Royal Marsden Hospital, including The Cancer Cookbook. And I asked her to answer some of the biggest questions when it comes to diet and cancer recovery. 

Clare 

I suppose people will experience very different things depending on their diagnosis of cancer. But diet nutrition can impact in various ways. First of all, a diagnosis of cancer in itself may have symptoms that impact on food intake. So the obvious ones we perhaps think about would be, say, a cancer of the head and neck or oesophagus, just the presence of that cancer may make it physically more difficult to eat. 

There is also a big psychological impact of having a diagnosis of cancer. So the worry and going through tests, and perhaps not feeling quite as well, that in itself can impact the way people want to eat, it may reduce their appetite. And then thirdly, when people actually start treatment, often treatment will impact either on their appetite, or their ability to eat, or their ability to prepare foods, so a lot of people may become fatigued. So suddenly, eating isn’t quite the same as it was before. And that in itself presents challenges for people. And they may find that they lose some weight, they don’t want to eat the foods they would normally eat. And often they will need a bit of help. 

Over the years I’ve seen quite a few situations where it can cause conflict either in a family or with carers. So the person with a diagnosis of cancer may find that they have some aversions to food, food doesn’t taste the same, maybe their appetite isn’t as great. But there is a level of anxiety in the family or with carers because they want that person to eat. So sometimes, a conversation which helps explore both sides of that equation is really important at helping people really decide what their goals are and how best to achieve those if somebody’s finding it difficult to eat well. 

Sophie 

Yeah that’s quite interesting and do you find that there are certain cancers or treatments which have a bigger impact on someone’s relationship with food? 

Clare 

Yeah I think it’s very, very individual. We know there are certain treatments where it’s very likely that people will experience similar types of symptoms. So if I use an example of say, radiotherapy to the head and neck, so if the mouth is included in that field of radiotherapy, it’s very likely the person will get a sore mouth. Very likely they will have taste changes where they find it much more difficult to detect tastes. 

But other treatments such as drugs, systemic anti-cancer therapies can be very different.  So you might have people who are on the same treatment plan, but they expect variants different symptoms say different taste changes. And those may be different as the treatment progresses. So I really encourage people to have a very sort of individualised approach, and to communicate with their healthcare team if they’re experiencing symptoms, because it might be there that there’s medication that can help. And over the years, we’ve seen a huge improvement in the way sickness is managed. So there are much better anti sickness drugs. So really, that does need a conversation with the healthcare team because there may be something very straightforward that can be done to help support that person and enable them to eat which is really important. 

In the period after treatment, there may be other elements that become more important. So for example, things like bone density, some hormonal treatments can influence bone density. The balance of diet and looking at nutrients like vitamin D and calcium, become important other elements like being physically active, etc. I think it’s also important to remember that some cancer treatments may have what we call late effects. So there may be impact on systems in the future that cause symptoms to arise. So a good example would be late effects to the gastrointestinal tract, which might be caused by radiotherapy, or, to a lesser extent, some of the chemotherapy, systemic anti cancer therapies. But we do know that pelvic or abdominal radiotherapy may cause changes in bowel habits, you know, beyond the end of treatment. So it’s really important to think about those symptoms and the interaction with diet for symptom management. And again, that’s a whole different approach, but diet can be used in some circumstances to help manage those symptoms, or late effects of treatment. 

Sophie 

Yeah and I think also it’s quite natural when you have questions about what you should eat or how to help with the symptoms you’ve just talked about, that you would do a quick google search to find the answers. But there’s a lot of misinformation on the internet, especially with diet. How do you advise people to navigate around that?   

Clare 

Yeah, oh you’re absolutely right, there are a lot of myths about diet and cancer out there. I would always encourage people to really think about where they’re getting their information from. So trusted websites. Some of the charities have got very good information. And they will be producing information that is evidence based, peer reviewed. So think about which websites you’re looking at. So Cancer Research UK, the World Cancer Research Fund, NHS Trusts, like the Royal Marsden, they will often have links to dietary information, and some of the professional groups. So the British Dietetic Association produce information for the general public. It’s peer reviewed, it’s written by dieticians. So really look at the sources, some individual cancer specific charities are also good. So bowel cancer charities, pancreatic cancer charities – very good information. So is it trusted information. So general information is usually very helpful, but sometimes people really struggle to relate it to themselves. So that’s sometimes where they do need help from a professional to try and make sense of it.   

Sophie 

One of the diets that gets a lot of attention and that we get a lot of questions about is the ketogenic diet, which also known as the keto diet, and that’s where you’re eating predominantly fats and protein. As a dietician what are your thoughts about the keto diet in terms of cancer recovery?  

Clare 

Yeah, the keto diet is very popular in terms of being discussed, with respect to diet and cancer. At this moment in time, we certainly don’t have sufficient evidence to be suggesting the keto diet should be used routinely. I think if people are trying the keto diet, it should only be under the umbrella of a clinical trial, where somebody is monitored for side effects for adherence, and for any metabolic response to that. But we certainly don’t recommend the keto diet for people with cancer at present. It’s a very difficult diet to follow and unless it’s done under proper guidance, it’s very likely that somebody will not be eating a well-balanced, healthy diet. 

I would very much encourage people to go back to the trusted resources and see whether whatever is being suggested, is that mainstream?  And where has the person got their evidence from? I mean, dieticians often get asked very specific individual questions about foods or particular diets. And the British Dietetic Association, the oncology specialist group have produced a leaflet on myths, dietary myths, which is available for anybody to find on the British Dietetic Association website. And we drill down a little bit more into what people are suggesting, and whether there is any evidence behind these. And you’re right individual snippets of information about foods or dietary regimens – if they’re not tried and tested, I would always ask, you know, is this something that is going to cause harm? And if it’s one small amount of an individual foods that you add in, it may well not cause harm. But if it’s significant changes in diet, that are difficult to implement, and there isn’t good evidence – they may also be causing harm because they’re making somebody exclude foods that they would normally eat. 

Sophie 

Yeah y’know I think when we talk about diet and especially ones that are meant to help us with recovery, I would automatically want to look for a diet that seems to fit all. So multiple people have said it works for them, so I’d assume it would work for me. But we know that’s not always the case – we all eat different foods day to day, we like different flavours and textures and we have different eating habits. 

So, y’know I guess those behaviours would extend to those with and beyond cancer, despite the changes experienced. And what works for one person won’t necessarily mean it will work for the next. So for example, if someone has experienced taste changes because of their cancer treatment you might not be able to recommend the same foods for all those people, because it’s just so individual. 

Clare 

Yes, it is very much person to person based. And I would say probably more linked to treatment than specific cancers. But it can be a challenge. And there are interestingly, there are also new approaches to taste changes as well. Trying to, and these are usually under a study/a scenario at the  moment, but getting people to use flavour sticks to or nasal sticks to smell flavours just to try and stimulate the tastebuds and the cells in the nose in the olfactory system to try and stimulate them back into action to be able to work, because they can be affected by drugs. So there are some studies and we’ve heard from a colleague in Germany, they’ve been doing some studies where they get people to use taste sticks to try and stimulate their taste buds and retrain them if you like get them get them working again. 

I think if it’s a particular problem somebody has, and you brought up taste changes, that is a particular challenge, because people will experience very different taste changes. And over the course of their treatment, those taste changes might change as well. So I would say, look for the tried and tested advice. But also, it might be that you need individualised advice. So there are some you know, there’s some good general information out there. And if we’re thinking about taste changes, it might be about flavours. It might be about, you know, recipes, it might be about thinking of simple things like you know, good mouth oral hygiene, is it about some of the drugs people are on. And that’s why sometimes I say it is useful to have a conversation because there might be some quite easy things that can make a big difference to the way people want to eat and drink or the way they cope with some of the challenges. 

Sophie 

During my chat with Clare, we talked about a syndrome called cachexia. It’s a wasting syndrome where the body loses fat and muscle and is often related to cancer. 

But cachexia isn’t just weight loss, it’s far more complex than that. The body experiences a metabolic change which uses proteins, carbohydrates, and fat at a significantly faster rate. It’s using up all this energy that food alone cannot replenish. 

Now it’s not a given that people with cancer will develop cachexia and those with early-stage cancers don’t usually experience cachexia. But around 8 out of 10 people with advanced cancer develop some degree of the syndrome. And around 30% of cancer deaths are linked to the presence of cancer cachexia. 

Clare 

We generally see in cachexia is that there is a wasting of body tissue, particularly muscle. And that may impact on the way people feel. So they may not feel as strong, they might find it more difficult to get out of a chair, we also see that people will lose body fat, so they might lose weight a little bit faster than perhaps they would expect on the food intake that they’re having. So it’s that combination of diet, and then the response and the metabolic changes that are occurring. 

Now that can affect treatment in a number of ways. So if somebody develops cachexia, before they start treatment, then they may be regarded as more frail and perhaps not as able to withstand the treatment that would be planned for them. So in some occasions, say if surgery is one of the treatment options, there may actually be a period of time before the surgery, where there is a concerted effort to try and help improve that person’s, say nutritional status and physical state before they actually have surgery. So first of all, it may impact on the treatment that is considered that they could tolerate. Secondly, if it occurs during treatment, then it may make it more difficult for that person to tolerate the treatment. And by that, say, if they were having systemic anti cancer, therapy, chemotherapy, it might be that they need more breaks in their treatment. It may be that they need a reduction in the dose of the treatment that they’re receiving. So it’s important that that malnutrition and cachexia is addressed and people are supported during their treatment, because it may impact on the optimal treatment pathway that that person would normally have. 

Sophie 

While there’s still a lot we don’t understand about cachexia at this point, research is making breakthroughs to tackle the mystery. Most recently, a study part of the Cancer Research UK TRACERx programme found distinct patterns of genes that were much more likely to be found in the tumours of those with cachexia. Which could lead to a way to diagnose the condition before symptoms appear. 

The researchers also found a high correlation of cachexia with levels of a protein that other studies have previously linked with appetite and weight loss in the blood. This protein is called GDF15. The researchers believe that by targeting this protein with treatment, they may be able to manage cachexia or prevent it completely. 

Though cachexia remains one of cancer’s biggest mysteries, it’s just one aspect of our metabolism that researchers are investigating. Others, like Professor Karen Vousden, Cancer Research UK’s former Chief Scientist and a Group Leader at the Francis Crick Institute, are looking into how we can utilise food to help tackle cancer. 

Karen 

Well I think over the past years it’s become really increasingly clear that metabolism plays an important role in allowing cancers to develop. So I guess we have to think about what is metabolism. To put very simply, metabolism is the way in which we can turn food into the components that make up our bodies, the building blocks of life if you like. And also provide the energy required to keep our bodies ticking over. So without metabolism, we couldn’t develop, grow, move, think or exist. So if we think about this, at the level of each cell, there’s huge and complex networks of metabolic reactions that allow cells to assimilate the nutrients from food and allow them to divide and grow and carry out all of the functions that they’re designed to do. But we now know that there are changes in cancer cell metabolism that accommodate these differences, and that these changes are necessary for cancers to survive and progress. So taken together, this raises the prospect that if we can interfere with these cancer specific metabolic changes, that could be an approach to developing new cancer therapies. 

Y’know cancers are incredibly metabolically active, they’re growing when, when they shouldn’t, where they shouldn’t, they move around, they show all kinds of behaviours that are not normal, which is course why they become cancers. And that leads to very high metabolic demands, that cancers have to satisfy in some way. So in some way, that leaves them vulnerable, because they need all these nutrients, they need all these metabolic pathways to be functioning in order for the cancer to survive. And, you know, the idea then is that if we can intervene with that, to stop the cancer accessing all the nutrients it needs, then we can essentially starve the cancer. 

Sophie 

So, you’re looking at how you can stop cancer cells from, I guess, stealing the nutrients we get from eating and therefore ‘starving’ them – but how can that be done without affecting our normal cells? 

Karen 

Yeah, I mean, that’s a good point. And that really comes to the heart of why cancers are so hard to treat. They’re uncontrolled if you like, because they’re really not that different from our normal cells.  And the idea would be that our normal cells in general don’t have such a high and specific demand for all these different nutrients so if we limited these nutrients we might have a selective effect on the viability of the cancer cells. 

Finding that what’s called the therapeutic window, the difference between the cancer cell and the normal cell so that you can target one and not the other, is really the holy grail of almost every cancer therapy.  

Sophie 

And part of that therapeutic window is what you’re doing at Faeth Therapeutics. So for our listeners could you explain a bit about what it is and how you’re finding the therapeutic window to starve cancer? 

Karen 

Sure, so Faeth Therapeutics is the company that was founded by me and several other researchers, the aim of it is to use precision nutrition for cancer treatment. So basically, that is an approach that’s built on a much more precise understanding of these nutritional demands of any given cancer. And we think that those demands will be different for different cancers in different people, different organs, different genetic backgrounds. So I think we will need information about the genetics of the cancer and the type of the cancer. And then if we understand all of that, we may be able to identify which specific nutrients each tumour relies on to survive and resist treatments, as I say that will be different for different cancers. So based on that, then we can match each patient with a specific precision nutritional intervention. So for example, a targeted reduction, or increase in selected critical nutrients in the diet. And that will result in the cancers being starved of the essential molecules that they depend on.  

Sophie 

Earlier in the episode Clare mentioned we still don’t know a lot about the effects of diet and cancer and that there is a huge need for further research on specific diets like the keto diet – well Karen and Faeth therapeutics are doing that research. 

Karen 

Our initial studies are looking at two particular diets. And one of them is a ketogenic diet. And one of them is diet that’s limited in certain non-essential amino acids. And we do have some evidence from these foundational studies that these diets will boost the efficacy of cancer therapies such as chemotherapy and radiotherapy. So, it’s important to remember that we’re not suggesting that precision nutrition is used as a solo treatment, but it’s going to be used in tandem with other cancer treatments. And we were sort of enthusiastic about this, because precision nutrition has been used for other diseases such as diabetes and epilepsy. But the power of nutrition has been somewhat neglected, I think, in our fight against cancer. I mean, actually, the nutritional advice that’s given to cancer patients tends to be pretty general and aimed at encouraging the patient to eat well and keep their weight up. But that isn’t really based on hard evidence, it’s just kind of you feel that that must be the right thing to do. But actually, when you understand the mechanisms, we’re realising that that advice isn’t so helpful and may in some cases even be counterproductive to the health of the patient. 

So, you know, I’d say precision nutrition depends on deep understanding on how cancer metabolism works, the genetic factors that determine which nutrients, if any, a particular cancer needs, and we’re really just at the beginning of understanding those issues. And that’s allowing us to make much more informed decisions about which nutritional approach would be beneficial to which cancer patient. 

Sophie 

Wow, that’s really interesting! Okay so it’s not saying that food alone is the answer, instead it’s looking at how can nutrition and diet be a partner in our treatments like as chemotherapy and radiation. And making that recovery I guess almost tailor-made to suit the individual?   

Karen 

Absolutely, yes, I think that that comes to the heart of it. And that’s the idea around the precision. So we know already that there are several different factors that will play into which what the nutritional requirements of any particular cancer are. So the genetics of the cancer, the type of cancer, the organ of origin, if you like, where the cancer is in the body. And also importantly, what other therapies the patient is being exposed to what chemotherapy is, which radiation therapies. So all of those things will have to be thought of together as a whole, before we can really make useful predictions as to which diet would be best. 

If you think about it, there’s three main pillars of cancer care at the moment, there’s surgery, radiotherapy, and therapeutics, which would include chemotherapy and other drugs. And we think that precision nutrition could become the fourth pillar of cancer care. So coordinating and cooperating with the other three to bring about better outcomes for cancer patients. So we’re thinking about modulating specific nutrients to improve cancer therapy, I think we’ve only scratched the surface of this so far. And we and many other people in the field are using experimental models and computational machine learning approaches to identify more and more opportunities. 

Sophie 

The great potential of precision nutrition is really exciting. It could change the way we think about what a ‘healthy diet’ means. Instead of your health professional saying ‘just eat healthily’ you would be provided an individual plan that fits you during your recovery from cancer. 

Karen 

It is clear that diet can be linked to cancer. And I think what’s really important for us now is to understand exactly how this happens to be very clear about the mechanism. Is it because some diets are likely to cause obesity? Is there something in the diet that promotes cancer development? And is it true that one size will fit all? I think that’s very unlikely, I think that we’re going to have to be much more targeted and specific about the dietary advice that we give to different individuals. But those are really interesting questions. Can we use specifically designed diets or nutrition general approaches to help cancer treatment? I think these are all open questions, I think we need to urgently find answers to them. It’s really exciting to think about how this could maybe interact with other new therapies that are showing huge amounts of promise. 

I think understanding the initial nutritional requirements of the anti-cancer immune cells would be a further refinement of this precision nutrition approach, you know that we’ve been talking about. And of course, none of this really speaks to understanding the role of diets in preventing cancer development. I’m just specifically looking at the area of using precision nutrition for cancer therapy. But then there’s a whole other area of interest in what really is a healthy diet, and how can we advise people on the best diet for each individual probably to lower their chances of developing cancer in the first place. 

Sophie 

The world of diet and cancer is vast and complex. There’s still a lot of questions and we’ve only been able to scratch the surface here. 

But with research like Clare and Karen’s we’re getting one step closer to understanding how our individual diets can have a huge impact on cancer treatment and recovery. 

We hope you’ve enjoyed this episode and a huge thank you to all our guests, Dr Clare Shaw and Professor Karen Vousden. 

You can explore our show notes for more information and resources on today’s topic. And don’t forget you can subscribe to the show wherever you get your podcasts to be the first to listen when new episodes drop. Also if you have time, please rate the show and leave a review, it helps a lot and lets us know you’re enjoying the episodes. 

That Cancer Conversation is produced by the digital news team at Cancer Research UK. Thanks for listening and talk to you next time.