Social determinants of health: why do they matter for cancer prevention and treatment?

A piece of paper showing the elements that make up the social determinants of health

As the final part of our series exploring health inequalities in cancer, Dr Ioana Vlad and Dr Vanessa Gordon-Dseagu look at why the likelihood of developing and dying from cancer varies markedly in society, in ways that are unequal and unfair.

At World Cancer Research Fund our work is driven by our vision of a world where no one develops a preventable cancer. We know that approximately 40% of cancers are preventable via changes to modifiable risk factors (including not smoking, avoiding the sun, eating a healthy diet, and maintaining a healthy body weight).

> More information can be found in our Cancer Prevention Recommendations

We also know that the likelihood of developing and dying from a preventable cancer varies markedly across societies, and in ways that are unequal and unfair. Within the UK, there are around 20,000 more cancer cases each year among those living in the most deprived areas. But not only are people living in deprivation more likely to develop cancer, they are also often diagnosed with cancer later and thus less likely to survive.

One of the reasons for this is poorer access to the healthcare they need, including screening services. This is the so-called postcode lottery of healthcare. These and other inequalities are discussed in a previous blog in this series.

Inequalities in cancer and the social determinants of health

Let’s expand the idea of a postcode lottery to Europe. Looking from afar, we see that a person living in the UK is more likely to die after a cancer diagnosis than a person in Norway, but less likely to die after a similar diagnosis than a person in Romania. So a key question is – why is cancer survival worse in the UK, Ireland, and eastern Europe than the rest of Europe?

These stark realities are linked to the social determinants of health. The World Health Organization defines the social determinants of health as “the conditions in which people are born, grow, work, live and age”. They include factors such as:

  • income
  • education
  • gender
  • race and ethnicity

These elements can also dictate the types of environments we live in: things like whether:

  • we have food security
  • we have access to education
  • our housing is safe, clean and stable
  • the air we breathe is free from pollution
  • we have access to green and open spaces to play and move

In short, they are the factors beyond medicine that influence our health.

Justice and health – what’s the link?

These social determinants, in turn, explain health inequalities – that is, the unfair and avoidable differences in health status and outcomes among and between different groups of people. These concepts can be difficult to understand and accept.

We want to think we are unique and in control of our own life and health, or, on the other end of the spectrum, we may find it is easier to think that our health is pre-determined, a matter of luck, and so out of our control.

However, it’s now well-established that not only is health distributed unfairly in our societies, but these inequalities follow something called a “social gradient”.

We know this by looking at the population of any country, and splitting it into categories by, say, income, education, or even how well off your neighbourhood is. The lower you are on the resulting scale, the lower your chance of living a longer, and healthier life.

When we do this, we find that people who have, for example, lower education levels also have worse health outcomes and a higher likelihood of developing a preventable cancer.

This is a pattern that we see again and again, across different settings. But if we don’t look closely enough we may miss how this is a matter of justice.

For example, data from England showed that in the 10 years between 2010–20, life expectancy decreased for some, and increased for others. The increases were seen for those living in the 10% richest neighbourhoods of London. The decreases were seen for those living in the 10% most deprived neighbourhoods in the north-east of England.

To further show how health inequalities are unfair and avoidable, let us look at overweight and obesity rates. We know that overweight and obesity is a leading modifiable risk factor for developing cancer – at least 13 cancers are associated with increased body weight.

We also know that our ability to maintain a healthy weight depends on complex factors that include making healthy food, and not junk food, most affordable and accessible, as well as environments that enable people to be active including safe cycling and walking lanes, and accessible green spaces.

Rates of obesity have nearly tripled worldwide in the past 4 decades. However, that increase was not uniform. Remember the social gradient? You guessed it, it applies here too. Overweight and obesity affected 56% of the adult population in London in 2021, but rates were lowest in the least deprived parts of the city, and highest in the most deprived. A similar pattern could be seen across England.

To tackle social determinants of health, we need policy action

It may be easy to conclude that there is something deterministic about poverty and “unhealthy behaviours” such as eating junk food. However, it’s possible to follow our Cancer Prevention Guidelines and reduce the risk of a preventable cancer – but it is just easier for some than others.

Extensive analyses show that a healthy diet is more expensive than one that simply covers calorie needs. It’s no wonder people would prioritise the latter when faced with limited money, time and choice. What’s more, companies have an incentive to push unhealthy products, and they seem to be advertising unhealthy foods by targeting young people in most deprived areas in particular. This is an example of when the social determinants become interlinked with commercial determinants of health.

Further, a recent report found that if you are a person of black, Asian or minority ethnic origin in England, you’re more than twice as likely as a white person to live in areas that are most deprived of green space.

Risk factors also have a cumulative effect, interacting with each other to make a diagnosis of cancer more likely. For example, a person who EITHER smokes or drinks alcohol will have a lower cancer risk than someone who smokes AND drinks.

It’s wrong and unfair that healthy environments are made less accessible to some, and that governments know what they need to do to, but do not act or do not do enough. This is why we need to demand policies and measures to improve environments, and when designing these all governments must make sure we keep justice in mind and do not leave people behind.

The patterns of health inequalities tell us, again and again, that there is something about our health that is determined by neither our personal choices nor solely by the genes we inherited. And that something comes down to differences related to social determinants of health, which are often unfair and could be made avoidable.

By recognising that where we live, and sometimes even who we are, impacts on our health in ways that are unfair, we will be able to tackle health inequalities, reduce the number of preventable cancers, and give people the best chance at being at the helm of their lives and health.