When people think of cancer, most of them often think of the link between tumour origination and DNA (damage) rather than metabolism. Cancer as a metabolic disease is an emerging concept that is gaining wider acceptance among open-minded scientists. In my next blog posts, I’d like to explore why there are so many mixed messages “out there” when it comes to cancer nutrition, why being 100% evidence-based in our decisions isn’t possible, which moves us on to the concept of cancer metabolism and cancer as a metabolic disease with all its implications for management of tumours.
The confusing world of cancer nutrition
Many things or substances whose effects on human health were debated centuries ago are now clearly acknowledged as being cancer-causing (or “carcinogenic” is a more sophisticated term) like for instance smoking, asbestos or certain paints. When it comes to nutrition, it’s a different story. There are so many mixed messages out there and it’s particularly confusing for somebody who has just been diagnosed with cancer and who is researching how nutrition can support them. Here are a few things that I came across when I did my research:
- Juicing is an absolute must for cancer patients VS Juicing is a really bad idea because it removes all the fibre and all you’re left with is sugar!
- Sugar feeds cancer VS There’s no link whatsoever between sugar and cancer
- Every cancer patient should take antioxidant supplements VS Antioxidants can “rescue” cancer cells, especially in patients undergoing cancer treatment
- Red meat causes cancer VS Red meat contains many cancer-fighting nutrients
- It’s crucial for cancer patients to have a good alkaline-acid balance because cancer can only thrive in an acidic environment VS Food doesn’t affect blood pH and acid/alkaline balance and there’s no point obsessing with it.
Confused? I totally get you… I was- and sometimes still am- too. It’s difficult, if not impossible, to navigate the cancer nutrition jungle. Compared to other scientific fields, nutrition science is still in its infancy and our field is facing even more challenges than other areas of science. Maybe this is because it’s incredibly difficult to find “subjects”, i.e. patients willing to participate in trials and, most importantly, be compliant with the dietary approach they’ve been allocated. And apart from recruitment- finding suitable candidates for a study- compliance is the next thing that can put a spanner in the works. Unless you lock people in and almost “force feed” them, there’s no way of knowing whether they really follow a certain diet. Let alone what else they do that could also have an impact on their well-being, like sleep, exercise, stress or other factors (these are called “confounding factors” in the world of research).
Is it possible to be 100% evidence-based?
In case you’re under the illusion that you can read a scientific study and think it’s 100% reliable, then please think again. I read this blog post here with interest where you can read that “in published medical research, 80% of non-randomized studies (by far the most common) are later found to be wrong. Even 25% of randomized studies and 15% of large randomized studies — the best of the best — turn out to be inadequate.”
Is it true that you could take a statement- i.e. x causes cancer- and then find studies supporting both sides of the “story”? Yes, it’s more common than not and incredibly confusing.
This means that in nutrition, more so than in any other field, we can’t blatantly ignore pre-clinical evidence behind a specific approach because there are no randomised placebo-controlled trials (the Gold standard in medicine). I explained earlier why these trials are so challenging to conduct. It’s similar to the ketogenic diet for cancer patients, for instance. There are various reasons why, especially in nutrition, it’s simply impossible to have a 100% evidence-based approach. In 2012, I decided to start guiding cancer patients- when they requested it- through the process of implementing the ketogenic diet in a safe and cautious way, for various reasons:
- My priority when I work with clients is “First do no harm” (have a look here for a very insightful movie). When an intervention- in my case the ketogenic diet- has a proven track record for safety, I feel confident enough to use my training and expertise with my clients. The results of large human clinical trials that are currently being done will take years to come in. And, the final straw came when a client said to me (that was back in 2012): “Patricia, I’m going to do the ketogenic diet anyway, whether you help me or not. Chances are that I screw myself up totally without your support, though!”
- This brings me to the next point. Many chronically ill people and cancer patients in particular don’t have the luxury of time. Many people who contact me are in advanced stages of cancer and they have been sent home with no treatment options. They’re still willing to try anything to stay alive, but waiting for a few months or even years to have “solid evidence” is simply not an option. I’m totally aware that for medical professionals, it’s important to draw a line with evidence. But refusing to give those people access to a DIETARY regime (we’re not talking about hard, untried drugs here!) that could help them improve their quality of life and give them hope is not a valid option either. And you can probably read between the lines that I’m talking as a cancer patient here!
- We have evidence to demonstrate the link between cancer and sugar. And how metabolism in a cancer cell is different to that in healthy cells. Abundant pre-clinical data combined with the demonstrated safety of a properly managed ketogenic diet from the epilepsy community has made this approach desirable even before the clinical trial data is available. The question is: How much more evidence do we need? Or, as Professor Rob Thomas states in an interview with Robin Daly: “If you have lots of foods that increase your glycaemic index (sugar, processed carbs or even overeating), then you have an increased risk of cancer. So how much evidence do you actually want. We’ve got laboratory data, we’ve got an underlying very feasible biochemical pathway which directly shows the link to cancer progression, we have large cohorts, too. [..] People want advice based on common sense. If some health professionals say “I’m going to wait for the randomised placebo-controlled trials on sugar to advise my clients”- first of all, this is never going to happen. And you have to draw a line in the sand somewhere with the level of data. […] Why is it such a sin when you have all this data showing sugar is bad that we can’t advise patients until an RCT (randomized controlled trial) comes out?”
- One thing that is used for certain drugs is something called “extrapolation”. Even among high-powered, statistically oriented clinicians, it’s in some cases acceptable to extrapolate data (or evidence) from one drug to another. This means that we use data from one trial on a particular drug for another, very similar drug. One example is for instance the use of Tamoxifen for 10 instead of 5 years, the data of which has been extrapolated to aromatase inhibitors. Why can’t this be similar for dietary approaches? We have so much evidence now that points to the detrimental effects of sugar for cancer patients in particular, so why do we have to wait for randomised controlled trials so that we can definitely use this dietary approach with patients who are waiting?
So, what’s the story with cancer and metabolism?
In my next blog post, I will explore the notion of “cancer as a metabolic disease” a lot more in-depth. What does it mean, why don’t we hear more about it and could cancer metabolism play a big role in cancer treatment in the future?