In some ways, our understanding of cancer has never been better: survival rates in the US for some versions of the disease, including breast cancer, have more than doubled over the past four decades. Today’s 10-year survival rate for breast cancer is 83 per cent, and for tumours caught before they metastasise from the breast, that figure jumps to 99 per cent.
For the first time in medical history, we are regularly conducting research not just on cancer patients, but cancer survivors. We now use breast-conserving surgery, radiation, therapies that stimulate the immune system, targeted therapies that block specific receptors essential to cancer growth, and even lab-engineered chimeric antigen receptor thymus (CAR-T) cells harvested from a patient, genetically modified, and then re-infused to fight cancer. Because of our advancements, a smaller percentage of patients are dying of cancer, and far more people are living with it.
But some tumour types, like glioblastoma or pancreatic cancer, have retained their dismal prognoses despite the billions of dollars in research funding that we’ve thrown at them.
And, although the survival rates are higher in the US than the UK – where outcomes remain lower than many comparable countries, with among the worst five-year survival rates for breast, lung, and colorectal – a lot of advancement comes at a hefty price; novel immuno-therapies, which UK patients don’t necessarily have the same access to, take billions of dollars to develop and are being sold to patients at a high cost.
The cost of cancer treatment has skyrocketed; it is the number one driver of healthcare spending and we will bankrupt ourselves if we focus only on treating cancer. We need to focus on preventing it.
For the longest time, we thought of cancer as related to smoking or genetics but there is so much more to the story. Over the past 30 years, as smoking rates have come down, the rates of cancer in young people have more than doubled; for the first time in history, my generation faces a worse mortality rate than our parents, fuelled by a roiling epidemic of young adult cancer.
While countless dollars and hours are funnelled toward cutting-edge therapies, we remain clueless about what’s causing this cancer epidemic afflicting our young adults. Is it skyrocketing rates of obesity, processed foods, microplastics, Covid-19, or something else entirely that we haven’t yet discovered?
The reason is likely obesity, which is linked with almost every type of solid malignancy there is. In the US, 70 per cent of adults are overweight or obese and in the UK the number of people who are overweight or obese is 66 per cent.
Excess fatty tissue causes inflammation, which sends your immune system into overdrive, rendering it unable to differentiate host from foe. That is the mechanism by which obesity causes cancer but a lot of other factors can increase inflammation, including an imbalance in the gut microbiome, which is called dysbiosis. Each of us has billions, if not trillions, of different bacteria cells that live in our colon and gut which work to decrease inflammation and train the immune system not to attack anything that seems different. Anything that disrupts it disrupts the training of the immune system, meaning that the bad bacteria take over the healthy ones, and limits the body’s ability to decrease inflammation.
As well as being caused by pollutants in air and water, dysbiosis comes about in part because of the ultra-processed food that is now so prevalent in our diet. Dysbiosis is different from inflammatory bowel disease, which is an autoimmune condition when your immune cells attack normal cells in your body without hesitation. It is more of a low-level chronic inflammation slowly brewing in our bodies. The immune system is not perfect and cancer is a game of chance.
Our bodies have lots of guard rails up but if random cells get hit by anything that promotes inflammation to a higher than normal level and that combines with one cell mutating to become cancerous, that is how tumours grow.
Cancer is an umbrella term for hundreds of diseases. But what we do know is that 40-50 per cent of cancer deaths are preventable. There are 10 million deaths a year from cancer worldwide so that means that 4 million deaths a year could be prevented. In the meantime people are dying that need not die.
So what do we need to do? We need to make changes to the way we live and organise our lives. Some things, like microplastics are ubiquitous – and out of our control. But if you are already living with obesity, there are many weight-loss medications that are highly effective. Ultra-processed food is very easy to avoid. We can decrease our alcohol intake. And we can choose not to smoke.
We do know that 40-50 per cent of cancer deaths are preventable. At 10 million deaths a year from cancer, that’s 4 million could be prevented
And, while we may not be able to totally eliminate these things from our lives, it is very realistic for the average person to decrease their cancer risk by 30 to 40 per cent by making optimal lifestyle choices.
The key to cancer prevention or healthy living in general is doing things in moderation; to recognise the aspects of our lifestyle that we know are maladaptive and make small tweaks. By far the best diet is one you can stick to for months or years so rather than eliminating alcohol that may mean decreasing from ten to two or three drinks a week. Or switching from drinking spirits to cider. Or making small dietary changes from white to wholewheat bread or white rice to brown. Making a series of small lifestyle tweaks is a good way to mitigate risk.
Some people take probiotics in a bid to promote healthy gut microbiome. If you have a specific gut condition or take antibiotics, they can be helpful but the best thing you can do is eat a healthy, balanced diet and avoid ultra-processed foods. Aim to minimise the cookies, crisps, and sandwiches that are tasty but also – to make them shelf stable – full of preservatives and chemicals that disrupt the gut microbiome.
Instead, eat more fruit, vegetables, fibre, lean meat and fish which will also help to maintain a healthy weight and decrease obesity. It sounds so simple, but especially at the moment, food is expensive and our lifestyles are stressful. We don’t always have time to make a healthy dinner from scratch and it is important to recognise that there is an economic element in that too.
Helicobacter pylori is a common, microscopic bacterium that is ubiquitous around the world. Something like half the population has this bacteria. But there is a mystery around why it causes some groups – and not others – to develop gut inflammation, stomach ulcers and dyspepsia. And why nations in East Asia, where H. pylori is common, have a gastric cancer risk up to 10 times that of the US, whereas the cancer rate in India, where H. pylori is even more common, is actually around the same as in the US.
There seems to be an ethnic difference. There is a genetic component and also a dietary one: India has some of the highest vegan and vegetarian populations, and the Indian diet has a significantly lower intake of meat and salted, pickled foods. And while the Japanese diet, typically high in vegetables and fish and low in meats, likely contributes to lower rates of obesity and longer life expectancy than in the US, it comes with the nasty side effect of gastric cancer risk. East Asians and Indigenous people of the Americas have the highest rates of stomach cancer worldwide. What they have in common (besides H. pylori) is a high consumption of smoked and preserved meats in their diet.
Gastric cancer is a relatively rare cancer in the US. But in Japan and Korea, the rate is over four times higher, and it is the most common cancer. Even East Asian immigrants to the US continue to have a much higher rate of gastric cancer as compared to other Americans. Without a doubt, H. pylori explains some of this disparity, but not all of it. The other major factor is probably pickled and salted foods: pickled vegetables and noodles are staples of the Japanese and Korean diets.
It seems that salt, especially in a fermented liquid, wears away at the lining of the stomach, causing something called “atrophic gastritis.” Over decades, this destruction of the stomach lining leads to mutations and stomach cancers. Observational studies of East Asian populations reveal about a 50 per cent increased risk of stomach cancer associated with high intake of pickled foods.
Be there is a distinction between pickled and fermented foods. Fermented foods like kimchi and miso actually promote healthy gut microbiome.
It’s also worth bearing in mind that there is no reason for everyone to test for H. pylori. But if you have chronic reflux or dyspepsia, heartburn, belching, and regurgitation for more than a few weeks, talk to your doctor. A lot of us have those symptoms from time to time because of our diets, stress and alcohol but if you have them chronically, it is very important to get tested.
A huge key to preventing cancer death is catching it early. If people have the screenings on offer to them like colonoscopies, mammograms and cervical smears, it will save thousands, if not millions of lives and also improve survival rates for the average person. However, since the pandemic, rates of screenings have remained lower than they used to be; something that will lead to tens of thousands of deaths. In the US it is linked partly to people without insurance who can’t afford to see doctors.
But there is a growing distrust in general of the medical profession. And there is also a lot of misinformation online being propagated by podcasters, supplement companies and people with ulterior motives who are selling a diet, a supplement, or a political agenda, and people are buying into that.
There is also, and I have personally seen, a huge rise in people not interested in vaccines and that seems to be getting worse with AI and other alternative sources of information. So I wanted to write a book based on medical information and science that is accessible and which people can understand. I hope that people will trust the data, trust the evidence and trust reputable sources rather than dubious ones.
As told to Victoria Young
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‘Outsmarting Cancer: Risk Reduction and the Power of Prevention’ by Adam Barsouk, MD and Oncology Fellow at Johns Hopkins University is out now
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