I'm a cancer doctor - these are the 6 biggest myths patients need to be aware of

Dr Liz O’Riordan (Image: Jenny Smith)

While researching my book I came across more than 60 cancer treatments I’d never heard of. And every week my social media followers ask me cancer-related questions.

Is it true that deodorants are dangerous?

Will juicing stop my cancer coming back?

Most of the questions are based on rumours, hearsay and common myths.

And when I do go looking for evidence to see if there’s an element of truth, there’s often nothing to find.

Sarah Cawood, a TV presenter who’s been treated for breast cancer, posted a video on Instagram last year, where she said: “I’m sick of the misinformation. I just don’t know who to believe anymore. I am actually gonna cry. I am so tired of it and just wish there was one person we could go to on the internet that is the party line on everything.

“There’s too much conflicting information – too much misinformation.

“Too many people all shouting really loudly in my echo chamber of post-cancer anxiety and I’ve had enough.”

And that’s where my book comes in. Cancer leaves you feeling vulnerable, emotional and scared.

I’ve been where you are. As a breast cancer patient, I’ve felt what you’re feeling.

I know how hard it is to think logically and rationally at a time like this. You want certainty and hope. The difficult truth that none of us want to hear is that no doctor can give you that promise.

There is no magic bullet that can cure every cancer.

But I want to give you the tools to spot misinformation whenever you come across it.

So here are some of the most common cancer myths.

There is no scientific evidence to prove sugar causes cancer. (Image: Peter Dazeley / Getty)

A popular “alternative medicine” doctor in the United States called Mark Hyman was interviewed for a YouTube channel. He declared: “70% of cancer is caused by food. Sugar is the number one culprit”.

Now that’s a terrifying thing to hear, especially if you’ve got a sweet tooth. And you’ll be grateful to hear it’s not true.

This myth began in the 1920s when a German scientist called Otto Warburg was studying rat cancer cells in his laboratory. Firstly, he noticed the cancer cells used a lot more glucose for fuel than healthy cells. And secondly, they weren’t using oxygen to break down glucose for fuel, whereas the healthy cells were.

He called this the Warburg Effect and it led to people believing sugar caused cancer. Dr Warburg thought the reason cancer cells didn’t use oxygen was because they had faulty mitochondria.

These mini-organs inside your cells use oxygen to turn one glucose molecule into 36 ATP molecules – the main energy source for every cell in your body.

Scientists have now shown it’s a mutation that makes cells switch to making ATP from glucose without oxygen in their mitochondria. The Warburg Effect is a consequence of that mutation.

We also know that 30% of cancers don’t have this mutation and many cancer cells have normal mitochondria that haven’t been damaged at all.

Plus cancer is a genetic disease, not a metabolic one. There is no scientific evidence to prove sugar causes cancer.

Bras do not cause cancer (Image: Oleg Elkov / Getty)

If you wear a bra, I’m sure you’ve had days when you wanted to rip it off and throw it in the bin. The wires dig in, it keeps moving around. You just feel uncomfortable.

However, some people will tell you underwired bras cause breast cancer.

It began in 1995 when a book called Dressed to Kill claimed wearing a bra for more than 12 hours a day greatly increased your risk of breast cancer.

The authors said this was because underwired bras restrict lymph drainage in the breast tissue. They claimed this led to a build-up of toxins in the breasts, which in turn caused cancer.

This is not true.

Firstly, lymph fluid in your breast tissue travels up and out to the lymph nodes in your armpit, not down towards the underwire. Secondly, lymph fluid is just the waste products of metabolism, bacteria, viruses and damaged cells. There are no toxins.

It is filtered in lymph nodes that trap or destroy anything harmful that the body doesn’t need, like bacteria. Waste products are reabsorbed back into the bloodstream where the liver and kidneys deal with them.

As long as your liver and kidneys are working properly, your body will get rid of anything it doesn’t need.

Every major international breast cancer charity and cancer health organisation states bras do not cause breast cancer.

Stress and negative emotions do not cause cancer. (Image: Getty)

One of the founding beliefs of alternative medicine is that toxic thoughts and negative emotions are part of the root cause of cancer.

You have to address your issues before you can be cured and if we can simply think more positively, our body will be in a better place to heal.

Dr Hamer, a German physician whose son was killed in a shooting accident, was one of the first people to make this claim.

A few years later, Dr Hamer developed testicular cancer. Having studied his cancer patients, he noticed they’d all had trauma in the preceding years.

He then claimed anyone who didn’t get help for anxiety, depression or stress would get cancer. But if you did get treatment, you could potentially cure your cancer.

However, he didn’t go on to cure thousands of patients. In fact, his medical licence was removed in 1986 for malpractice and he was imprisoned.

The Swiss Cancer League described his theory as “dangerous, especially as it lulls patients into a false sense of security

so they are deprived of other effective treatments”.

Stress and negative emotions do not cause cancer. Some of us want to believe it because it ties into our need for control. A cancer diagnosis comes with a wave of negative emotions – guilt, fear, anxiety, panic – and can lead to clinical depression.

This is normal while we come to terms with everything that is happening to us.

Staying positive will help you eat better and exercise more, and these can have a big impact on your life ahead.

But it’s what you eat and how you move that is having the effect, not what you’re thinking. The bad days will pass, and remember that most people diagnosed with cancer will be cured.

We are told that dangerous heavy metals like aluminium can be absorbed through the skin. (Image: Getty)

I had no idea people thought they were dangerous until someone sent me a video on TikTok saying anti-perspirants cause breast cancer. This myth began with a viral email in the late 1990s based on a bad understanding of biology.

The author believed toxins were eliminated in our sweat. Because anti-perspirants block sweat, they believed this led to a build-up of toxins in the lymph nodes in our armpits. But sweat glands have nothing to do with toxins or lymph nodes.

Another myth that led to many people avoiding anti-perspirants was that they contained aluminium. We are told that dangerous heavy metals like aluminium can be absorbed through the skin.

When this happens, the aluminium acts like oestrogen and causes breast cancer.

Also, if you shave your armpits, you create tiny little cuts in the skin and more aluminium can be absorbed (the final reasoning is that breast cancer is only rare in men because they don’t shave their armpits).

Aluminium can cause cancer but only in very high concentrations when it can damage your DNA. However, it is very hard to absorb from your gut, and your kidneys get rid of any excess in the urine.

So, if your kidneys are working properly, you don’t need to worry.

One study compared almost 1,000 women with and without breast cancer. There was no difference between those who used anti-perspirants and those who didn’t. They also showed that shaving your armpits made no difference to your risk of cancer.

You don’t need to have your fillings removed to stop you getting cancer. (Image: Getty)

The root canal myth started in 1922 when a dentist called Weston Price said dental surgery caused a variety of illnesses.

Fast forward to 2019 and a documentary called Root Cause, which claimed root canal surgery can’t remove all the bacteria in the teeth, leading to chronic inflammation and cancer.

A high-profile American osteopath called Joseph Mercola claimed 93% of breast cancer patients have had root canal surgery, therefore root canal surgery caused their cancer. There is no evidence of this.

Every international dental association states root canal treatments do not cause cancer. The film Root Cause has now been removed from streaming sites.

In the 1970s an American dentist called Hal Huggins linked amalgam fillings to multiple sclerosis and cancer without any robust evidence.

He started removing amalgam fillings and extracting teeth that had been treated with root canal surgery.

In 1996 his licence to practise dentistry was revoked. There is absolutely no evidence that amalgam fillings cause cancer.

The American Dental Association, the Oral Health Foundation, the British Dental Association and the World Health Organization, to name a few, all agree on this. You don’t need to have your fillings removed to stop you getting cancer.

I had no idea what a paraben was until I started researching my book for cancer myths. I fell down a rabbit hole.

Parabens are apparently everywhere in everything and should be avoided at all costs. I started panicking.

Had I missed something? What were parabens and do they really cause cancer?

Parabens are preservatives. They are naturally found in fruit like blueberries and grapes, as well as rivers, soil and house dust.

There are also man-made parabens used as preservatives in our cosmetics, toiletries and food.

This cancer myth started with a now-deleted Facebook post that said “99% of cancer is caused by parabens in beauty products, skin products, home fragrance”.

That is a really scary thing to read.

It came from a 2004 study published by Prof Philippa Darbre, who looked at 20 breast cancer samples and found they contained parabens.

This was wrongly interpreted as proof that parabens caused breast cancer, and started a global panic.

But Professor Darbre’s research did not prove that parabens cause breast cancer.

She only noted that they were found in breast cancer cells. She hadn’t looked at normal breast tissue.

The American Cancer Society, the US Food and Drug Administration, the Cos-metic Ingredient Review organisation, the Scandinavian Society of Cosmetic Chemists and CRUK have all reviewed the available literature and concluded that parabens are safe and do not cause cancer.

● Edited extract by Matt Nixson, from The Cancer Roadmap: Real Science To Guide Your Treatment Path, by Dr Liz O’Riordan (HarperCollins, £16.99)