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Let's beat cancer sooner

Causes of cancer can be placed into two rough camps: things we can control, and others that we can’t.

The latter includes things like random changes to our genes as we get older, or those that are passed down through families. By their nature, there’s not much we can do about these risks. But for the many causes we do have some control over, such as smoking, there’s a potentially life-saving chance to act.

Armed with information about what increases our risk, we can consider making changes that stack the odds of avoiding cancer in our favour. And politicians can see where action is needed most.

The goal of new data we’ve released today is to provide that information.

The data comes from a new landmark study led by Cancer Research UK researchers. It looks at the things in our lives that cause cancer and calculates how many cases in the UK are linked to each of these risk factors. We’ve done calculations like this before, but this new research uses all the latest available data and evidence to give more accurate estimates. And because some risk factors have become more common since the previous analysis, and others have become less common, it’s important to update these figures.

The findings, published in the British Journal of Cancer, show that more than 135,000 cases of cancer could be prevented in the UK each year largely through lifestyle changes – that’s around 4 in 10 cases.

And while what’s behind these cancers may not come as a surprise, the results confirm how the things we do each day can add up.

What you need to know

First, calculating these numbers isn’t about blaming someone for their cancer. This research can’t tell us what caused an individual person’s cancer – it’s almost impossible to say that for sure. It’s also important to note that this doesn’t mean that some of the remaining 6 out of 10 cancer cases can’t be prevented. It’s likely that research will uncover some other causes of cancer, or show that some known causes are linked to more types of cancer than we think, so there are some unknowns.

This research is about providing clear information on where the different causes of cancer rank against one another, to encourage people to consider making positive changes, and highlight where government can focus its efforts to prevent more cases of cancer.

“We took data from national surveys showing how common each risk factor is in the population, and data from the UK cancer registries showing how many cases of each cancer type there are. Then we searched published research for information on how much each risk factor increases cancer risk, using only gold standard epidemiology research,” says Dr Katrina Brown, who led the analysis at Cancer Research UK.

“For example, those studies compared the number of cancers in people who smoke to the number of cancers in people who are non-smokers, to get a relative risk of cancer in smokers. We used that information, along with data on how common smoking is in the UK and how many cases of smoking-related cancer types there are, to estimate how many of those cancer cases overall are due to smoking,”

The team did this for all the modifiable risk factors and found that in total, more than 135,000 cases of cancer could be prevented through changes such as:

  • Stopping smoking
  • Keeping a healthy weight
  • Eating a healthy diet
  • Enjoying the sun safely
  • Avoiding certain substances at work
  • Protecting against certain infections
  • Cutting back on alcohol
Preventable cancers

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This is also why we want the Government to make the healthy choice the easy choice. And we’re doing lots of research into other ways to prevent cancer, including studying if drugs that are already available, such as aspirin, can reduce the risk.

Prevention works

This latest study confirms, once again, that smoking is the biggest cause of cancer. It’s responsible for a huge 54,300 cases of cancer every year in the UK, according to our new calculations.

But the good news is that the latest data point to how prevention can be – and has been – a success.

Over recent decades, smoking rates in the UK have fallen considerably. And alongside this, we’ve also seen the proportion of cancer cases caused by smoking fall in the last five years. Fewer people smoking means fewer cancer cases caused by smoking.

Smoking cancer prevention

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But the results also underscore how we can’t be complacent when it comes to tobacco.

“Even though smoking prevalence is falling in the population, smoking has a massive impact on the cancer risk of people who do it, therefore it’s still generating a huge number of cancer cases,” says Brown.

The number of UK smokers has fallen, and we hope that will continue, so the proportion of cancers caused by smoking will continue to follow that trend too.

This success also highlights how changes at the population level could reduce the impact of other cancer risk factors too. And obesity is an important example of this.

Obesity causes more than 60 cases of cancer a day

Being overweight or obese increases the risk of 13 different types of cancer, and causes around 22,800 cases of cancer in the UK every year, according to the new data. That makes it the second biggest cause of cancer in the UK after smoking.

Obesity overweight cancer

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But only 15% of people know that obesity causes cancer. So this is an important issue to raise, which is the aim of our much-discussed national awareness campaign. Unlike smoking rates, obesity levels have overall risen over the last couple of decades. And if we don’t act, the number of cancer cases caused by obesity will follow this trend too.

What does this mean for me?

It’s important to say again that this research can’t tell what has caused or will cause an individual’s cancer. The data come from comparing large groups of people. So, while research has shown that, for example, being overweight can increase the risk of cancer, it doesn’t mean you will definitely get cancer if you are overweight. And this is true for the other risk factors as well.

“This research was looking at the impact of these risk factors on a population level, rather than the effect they would have for an individual person,” says Brown. “But it can give us an indication of the relative importance of the risk factors for individuals. This is because it considers how much the factor increases individual risk, how many cancer types are affected, and whether those are common cancer types.”

Adding up the number of UK cancer cases caused by these risk factors confirms that around 4 in 10 are preventable. This shows there are steps we can all take to reduce our risk of cancer.

Prevention is not a promise. We can’t say for sure that not smoking, keeping a healthy weight or avoiding alcohol will mean you won’t get cancer, but it could help stack the odds in your favour.

To help pick out where you might start, we’ve built an interactive health checker that can help you understand what raises your risk and what you can do to reduce it.

Give it a go: What’s my cancer risk?

Sophia Lowes is a health information officer at Cancer Research UK

Find out more about all the causes of cancer included in the analysis on our website.

We’ll be following up on other ways to prevent cancer, such as chemoprevention, screening and HPV vaccination in another blog post next week.


Brown, et al. (2018) The fraction of cancer attributable to modifiable risk factors in England, Wales, Scotland, Northern Ireland, and the United Kingdom in 2015. BJC. 10.1038/s41416-018-0029-6DOI:


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Eileen Pollard April 12, 2018

Very informative and some preventative measures I already practise,not smoking, only a couple of drinks a week,walk into town when weather good,don’t sunbathe anymore,trying to loose weight,but keep the blogs coming.Thank you

Paul speed April 11, 2018

Changing a few ways I live
Like cutting down on alcohol
Eating sensibly
I don’t smoke anyway
But I also believe in living life
And not worrying so much

David April 7, 2018

I am 87 years old, mobile and active, and have followed all your recommendations for most of my life. Since retirement I have had prostate cancer at 74, now in remission after extensive treatment, and at 84 I had colon cancer, dealt with by major surgery. I am not convinced by the suppositions and extrapolations made from the statistics. Most cancers develop later in life, but we do not know why for certain. Some can be attributed to the causes you mention, but a great many cannot. The ageing process needs more research, and there may well be some substance in the Biblical “three score years and ten” lifespan.

David, Norwich

Kristina April 7, 2018


Caroline Wrench April 7, 2018

As per usual, people have not read or understood the article properly and have gone straight on the defensive! It is not saying that ALL cancers are caused by certain lifestyle factors, just that certain lifestyle factors can stack the odds against you. The article quite clearly says that it is not about blaming someone for their cancer and that research cannot tell what has caused or will cause an individual’s cancer. Smoking increases your chances but not all smokers get cancer, being overweight increases your chances but not all overweight people get cancer etc etc. Wish people would read things properly!

Amanda Watson April 7, 2018

A very well written document which is easy to understand. Would be useful to have some of the graphics advertised.

Patricia Jones April 6, 2018

I am none of the above yet have cancer!!!
I am not over weight, never smoked, only had a drink at weddings and special occasions, and not a sun lover, so how comes I have stage 3/4 oesophagus cancer.

Charles Purnell April 6, 2018

Unimpressed. Prevention? – VACCINATE! When did helicobacter pylori suddenly appear on the cause list? You give no info on this…When are you going to write about all the immunotherapy advances, eg 97% of blood cancers cured in mice, on to human trials…You could usefully do a review of the ‘out there’ treatments,eg blinotumomab, and the developments in trial. What happened to all the collaborations Micromet had, with Medimmune, Boehringer, Sanofi, Bayer etc., when Amgen got it, and the FDA finally woke up?

Katie Jackson April 6, 2018

Interesting yet doesn’t really tell us anything different from what we have been told before. Take me for example- I have never been overweight, never smoked, drunk very little alcohol, breastfeed 2 children until 13 months old, always been physically active and eat a healthy diet with plenty of vegetables and fruit. I have no history of breast cancer in my family but in 2009 I was diagnosed with breast cancer- why? What mistakes have I supposedly made? This is what I would like to know and will this dreadful disease be coming back. What should I be doing next to prevent its return!

Susannah jackson April 6, 2018

Was very interesting and amazed by the thing’s that can cause it

Cc April 6, 2018

While this is shown as news here, it’s old news elsewhere, and often elsewhere with more and more pertinent examples. This feels like a wasted opportunity to educate us all as to real and necessary lifestyle changes. Don’t drink the water. Avoid wifi routers. Don’t eat processed, dairy or white foods.

Sarah April 5, 2018

My dad died of cancer he had stopped smoking some years before my mom also died of secondary cancer and had never smoked and rarely drank so I think it’s unfair to say smoking and alcohol cause cancer no one realy knows what causes it I do think there is a cure already no Royals ever due of cancer but we will never be told of the cure because there would be to many in the population because people will be living longer as most people theses day seem to be dieing from cancer

Janet Little April 5, 2018

We need to spread the word

DocMills March 26, 2018

The new calculations LINK lifestyle factors to 4 in 10 cancer cases, but DO NOT SHOW that 1) the lifestyle factors caused the cancer, or that 2) changing lifestyle factors (i.e. losing weight) prevents cancer.

Gillian Goode March 25, 2018

Until I see clear data that is proven, I don’t think we even know yet what causes cancer , I think it’s unfair to say that smoking causes most cancers . There are millions that have died from all cancers ,including throat ,lungs and many other cancers ,that have never smoked in their lives, or worked in pubs and places where people used to smoke a lot. Babies and children who sadly die from cancer . I have personally known people who have died from cancer ,who have never smoked ,drank or was obese and led healthy lifestyles . I really hope that in the future we will find out the true cause and treatments to cure it . Every week there is a different theory of what might cause cancer ,I still really don’t think that health professionals know,and until I see proven facts of the causes ,I think the same .

PS March 25, 2018

No prostate indicator on your diagram? Isn’t that almost up there (in numbers) with breast and bowel cancer?

Jo streat March 23, 2018

When will people start talking more seriously about the research on the microbiome and eating fermented foods to support our gut bacteria as they are meant to support a huge percentage of our immune system and research is showing that a sick microbiome is linked to obesity, diabetes, mental health, dementia and also cancer as well as the more obvious IBD type diagnoses which can progress to bowel cancer. Also epigenetics is a fascinating and emerging field showing that lifestyle can switch genes on and off. It would be great if these things could also be covered so that people start to nurture their microbiome.

Patrick McGuire March 23, 2018

An informative, supportive and clear blog building on the excellent recent CRUK Obesity campaign. We can’t do anything about the hand we are dealt but we can make informed choices about the lifestyle we lead.

Dr Peter Lewis March 23, 2018

you exaggerate the risk of sin cancer from sunshine exposure. There is good evidence that Vitamin D protects against many forms of cancer (such as the academic work by Hollick in the USA). Sun exposure also protect against depression and other mental conditions and improves cardiovascular health.