In The Cancer Code: A Revolutionary New Understanding of a Medical Mystery, Fung hypothesises that we’re fighting the war on cancer with one arm behind our back, ignoring a key contributor to the seriousness of the illness half of us will get in our lifetime, according to Cancer Research UK. He believes we need to pay more attention to how the dysregulation of insulin in our bodies – caused by obesity and type 2 diabetes – can increase the risk of contracting cancer.
“We’re stuck in this paradigm of cancer as a sort of genetic freak accident,” says Fung. “It’s not really. It’s much more complex than that.” We as a human race recognise that cancer is a mutation of cells gone wrong, resulting in something malicious and malign attacking our bodies, replicating and multiplying. But, he says, we don’t think about why that mutation has happened, taking it a step further back.
“What you see is not a random occurrence,” Fung explains. He compares it to the writing of an article like this one: “It’s not just this random jumble of letters or words you happen to throw on a page that land in a perfectly-worded way. We’re trying to understand how cancer actually evolves, and the reason this is important is that something is evolving.”
We understand that in lung cancer: smoke too many cigarettes, and the inhalation of tobacco smoke leads to the triggering of growth of cancerous cells. But for many other cancers – and for the contribution towards lung cancer – we tend to overlook diet. “The biggest frontier we’re looking at now is diet and nutrition, and what parts of the diet are really that important for the development of cancer,” says Fung.
The link between insulin and cancer has long been hypothesised, but there remains no real smoking gun. “Insulin excess is assumed to be a cancer-promoting factor in patients,” explains one recent academic paper published in the academic journal Cell, but “our understanding of the insulin–cancer relationship is incomplete, and clinical studies have not clarified its relevance because of inappropriate design”.
Yet Fung believes that the link is obvious: we know that insulin and other hormones act as nutrient sensors in our bodies. When we eat, our insulin spikes and tells our body that food is available, encouraging growth and the expending of energy in cells. “We recognise that it’s not only important for energy metabolism but is also a very, very important growth factor,” says Fung. However, every time our cells divide and our bodies grow, we’re “tipping the scales more towards the development of cancer,” he says.
It’s a further explication of what we already know: obesity is linked inextricably with higher cancer rates, according to Cancer Research UK. In fact, being overweight is the second-biggest preventable cause of cancer, contributing to one in 20 cases. The World Health Organisation says there’s evidence to link 13 different kinds of cancer, including breast cancer and colorectal cancer – the second and third most prevalent on the planet – to obesity.
The solutions are simple, Fung suggests. We need to try and reduce our insulin intake, and therefore the increase in division and action in our cells that could cause cancer. That’s done by laying down the chocolate bar and starting to snack on something a little healthier. “If you’re eating a lot of refined carbohydrates, refined foods and junk food, they’re going to lead to obesity, which is going to lead to diabetes, which is going to lead to cancer,” he says.
Doing so could lead to a lowering of the risk of breast cancer in an American or British woman by a factor of two or three, he reckons. “If you take a Japanese woman and move her to San Francisco, her risk of breast cancer within a couple of generations doubles or triples because it’s not the genetics of it; it’s the environment that dictates your risk.”
Fung wants us to move away from the genetic consideration of how cancer comes to us and to instead think of it as an evolutionary paradigm. “We should treat this as almost an evolution, this cell that evolves into sort of like an invasive species if you will,” he says. And we should take the same approach we did to lung cancer in recent decades. “When we figured out smoking was a big risk factor for lung cancer, we said: ‘You need to stop smoking.’ We know obesity and type 2 diabetes are big risk factors for certain types of cancer. So we need to change our diet to cut down a lot of the refined foods and our sugar intake, for example.”
That’s obviously difficult given the extra stresses and strains not only on our minds but on our pockets, and the cheap availability of processed, high-sugar, refined foods. But if it’s possible, Fung says making changes could have a big impact.
“If you take it to the extreme and live your whole life like that, you can actually virtually eradicate cancer,” he says. As evidence he points to research carried out on people living in the Arctic Circle in the 1930s and 1940s to find out why they were ‘immune’ to cancer. “As these people adopted western lifestyles in the 1960s and 1970s, they all got cancer,” he says. “Clearly, they were not immune at all; it was their lifestyle and that they consumed so little processed food that affected them, and meant they never got cancer.”
The Cancer Code : A Revolutionary New Understanding of a Medical Mystery by Dr Jason Fung (Thorsons) is out now. Order from Telegraph Books for £14.99 or call 0844 871 1514