‘My grandpa smoked like a chimney, drank like a fish, ate whatever he wanted, and still lived to a ripe old age. But my friend was a tee-total, non-smoking veggie and still got cancer – so how can you say that her lifestyle caused it?’
Sound familiar? Many of us know someone who fits the first description. And at the other end of the spectrum, some people who lead the healthiest of lifestyles are still unfortunate enough to develop cancer.
So it’s no wonder that when we talk about lifestyle and cancer, some people are quick to dismiss the evidence and take a fatalistic view – after all, what’s the point of being healthy if it’s no guarantee against disease?
And it’s true that healthy living certainly isn’t a cast-iron guarantee against developing cancer, or any other illness.
But in the same way that wearing a seat belt and sticking to the rules of the road are behaviours that reduce (but don’t eradicate) your chances of being hurt or killed in a car crash, leading a healthy lifestyle by, for example, not smoking and keeping active is about stacking the odds in your favour, in some cases very significantly.
But another thing we sometimes hear from some people with cancer – and that we felt it was hugely important to address – is that they feel the finger of blame is being pointed at them when they read or hear about the preventable causes of cancer in the media.
Indeed, a glance through some of the heartfelt comments underneath this article highlights how strongly people feel.
Several people wrote about the media being “judgemental” and having a “moralistic streak” when talking about the preventable causes of disease. But most concerning, some cancer patients said that the coverage made them “feel guilty” about their disease.
We don’t want anybody with cancer to feel that they are in some way at fault for their disease. Apportioning blame under these circumstances isn’t only tremendously insensitive, it’s also unscientific (more on this later).
But understanding the causes of cancer – how our genes, our environment and our behaviour all interact – is a crucial focus for researchers worldwide, including many we support. And, since we’re publicly funded, we have a moral duty to communicate these researchers’ findings to the public.
But how should we go about telling people about the results of this work, without playing the “blame game”?
Empowerment not blame
It’s a cliché, but one worth repeating with the volume dial cranked up to 11 – prevention really is better than cure. By understanding the controllable causes of cancer, we can equip individuals with the information they need to reduce their risk of cancer.
But such information is categorically not about blaming people with cancer. To return to our earlier analogy, studies on the use of seatbelts are about safeguarding future drivers (and not about blaming people who’ve been in traffic accidents). Similarly, studies about lifestyle and cancer are about preventing future cancer cases.
To take the analogy further, car safety information also feeds into the wider public’s perception of driving, and can help bring about changes in behaviour. For example, it’s now widely accepted that wearing a seatbelt is a sensible precaution when driving, which is now enshrined in law and has undoubtedly saved many lives
Similarly, the overwhelming evidence that smoking causes cancer has gradually percolated into the public mind, and has helped make the case for anti-smoking legislation in many countries around the world.
Stricter legislation and taxation, along with public health campaigning, has helped many thousands of people quit the habit, contributing to a drop in smoking-related cancers – a trend we’re determined to see continue.
But beyond smoking, we know that that it can be hard to get a grip on some of the other preventable causes of cancer. It’s no wonder – stories about diet, lifestyle and cancer frequently appear in the media, sometimes with conflicting information.
This coverage gives the incorrect perception that the evidence base shifts drastically from one week to the next, and that “scientists don’t know what they’re talking about” when it comes to cancer risks.
This simply isn’t true. The evidence on lifestyle and cancer has been built through decades of research, and has cemented a handful of key lifestyle changes that can reduce the chances of developing cancer. Top of the list is to quit smoking, and the others are:
- keeping a healthy body weight;
- cutting back on alcohol;
- eating a healthy, balanced diet;
- keeping active;
- and staying safe in the sun.
To take one example from this list, there’s a huge weight of evidence showing that alcohol can cause seven types of cancer. Scientists have been confident about the link between alcohol and cancer since the 1980s [pdf].
Yet – and this is crucial – only around a third of people know that alcohol increases the risk of cancer. To change things in the same way we’ve helped reduce smoking rates, this gap between what the evidence tells us and what the public understands needs to be closed.
The stakes are high – the latest estimate is that more than 100,000 cancers every year are down to tobacco, diet, alcohol and obesity.
This statistic alone tells you why we will continue to bang the drum about lifestyle and cancer.
Walk through a minefield
So we know how to reduce the risk of cancer, and can estimate the total proportion of cancers caused by unhealthy living. Does this mean we can we spot ‘unhealthy’ people and say, unequivocally, that they will develop the disease?
Just as it’s not possible to say exactly who will crash as a result of risky driving (but you can say that such behaviour generally increase the chances of crashing), it’s not yet possible to categorically pin down specific people who will develop cancer based on their lifestyle.
Why? Because lifestyle isn’t the only thing that contributes to cancer. Broadly speaking, all cancers are caused by faulty or damaged genes.
And this damage can come from several sources. People can inherit these faults from their parents; they can accrue by chance over their life; or DNA damage can develop as a result of exposure to carcinogens such as tobacco smoke or ultraviolet light from the sun.
But not every bit of damage to your genes leads to cancer. The damage needs to occur in particular genes to do so.
So, just as you might emerge safely from a walk through a minefield, there are cases of lifelong heavy smokers living well into their 90s, and beyond. And such people – who survive to a ripe old age despite such unhealthy habits – often loom large in popular imagination.
But these people are the exception to the rule. Perhaps they have a particularly robust genome, or are just plain lucky. This doesn’t take away from the fact that smokers are overwhelmingly more likely to develop cancer than non-smokers.
The broader point is that you can control many aspects of your lifestyle, but there’s not a whole lot you can do to affect chance events or the genetic hand you’re dealt by your parents.
From statistics to the individual
Another reason is much geekier and involves a bit of statistical jargon.
Estimates of how many cancers are caused by lifestyle are calculated by researchers called epidemiologists. They look at health patterns across whole populations and try to match different factors – such as smoking or weight – to the chances of developing a particular disease.
A common way epidemiologists measure how a lifestyle factor such as smoking contributes to disease is to calculate ‘population attributable fractions‘.
These calculations represent the proportion of deaths in the whole population that could be prevented if a cause of death (such as smoking) were at an ideal ‘safe’ level (in the case of smoking, zero tobacco use).
But, by definition, these figures don’t tell you about specific individuals. They are about populations (of hundreds, thousands, or millions of people).
In other words, epidemiologists are excellent at estimating how risky behaviours affect large groups of people, but they’re no good at predicting what will happen to individuals.
An ounce of prevention…
Where does this leave us, a charity whose aim is to ‘beat cancer’?
Cancer is not a single disease – it’s a group of hundreds of different, often complex, diseases, with a range of causes. The connection is that all cancers are down to our healthy cells going rogue, ignoring the normal rules of meticulously synchronized cell behaviour, and dividing out of control.
Together, this group of diseases cause almost 1 in every 4 deaths in the UK. The good news is that more people are surviving cancer than ever before, and better treatments to kill off these rogue cells will undoubtedly save more lives in the future.
But treatment is only part of the solution – we need other tools in our toolbox to beat the disease. And it’s indisputable that one of our most powerful tools against cancer is the in-depth knowledge we now have about its causes.
Of course, none of us lead a risk-free life – we all succumb to temptation in some guise, whether that’s an extra glass or two of wine, going supersize on a take-away, or skipping that trip to the gym or run. We all have our own ‘guilty pleasures’, and it’s not our intention to police people’s lives.
But surveys show that people fear cancer more than any other serious illness. So we hope that providing clear information about how lifestyle affects cancer risk will support people in making longer-term, positive changes to help reduce their risk of the disease, if they wish to.
We also know that people affected by cancer can be keen to pass this information on to their friends and family.
Although he certainly didn’t have cancer prevention in mind when he said it, Benjamin Franklin was right on the money when he suggested ‘an ounce of prevention is worth a pound of cure’.
We don’t want to blame patients for their disease, in any way. These are the people we come to work for, day in, day out.
But helping others who are lucky enough to be healthy understand what they can do to reduce their risk is a major part of our fight against this formidable disease.
And we will continue to provide information about what the science says, and to bang the cancer prevention drum loudly.
Anything less is a dereliction of our moral duty to beat this disease.