Associate feature: Deprivation, obesity and cancer

Cancer survivor Rosa Macpherson at a Cancer Research UK event - Image credit: Cancer Research UK

“Diet is a major risk factor. It’s a major factor contributing to preventable cancers,” explains Linda Bauld, Professor of Health Policy at the University of Stirling and Cancer Research UK’s prevention champion.

“In terms of overweight and obesity, diet is the main factor that is related to cancers, and that’s because, essentially, what we consume and what the biological mechanisms are is far more important than whether we’re active or not,” she adds.

Bauld tells Holyrood that the effect of the extra weight has an impact on the likelihood of developing cancer in at least three ways.

If we carry more weight, extra fat cells change how our body works. Bauld explains that one of the changes relates to sex hormones such as oestrogen.

More oestrogen circulating in the system can contribute to cells multiplying more rapidly in particular parts of the body, like the womb or breasts, which can increase the risk of cancer.

Another mechanism, she points out, is insulin. When people are carrying a lot of extra weight, the regulation of insulin in their system isn’t optimum and insulin levels can rise.

This can result in cells multiplying more rapidly, which some research tells us is relevant to cancer developing.

And finally, there’s inflammation, where cells in fat release chemicals which encourage existing cells to divide including those that contribute to the formation of tumours.

Bauld says: “We know a lot about how extra weight and poor diet might impact on cancer.

This includes specific cancers, like colon cancer, where we know people who eat a diet that’s very low in fibre, it doesn’t keep things moving through their system as quickly as you would want, and again, that affects the cells in that part of the body and that might contribute to cancer developing.”

Diet and obesity is the second biggest cause of preventable cancer in the UK, after smoking, relating to around one in 20 cancers.

When you consider the dietary risk factors – such as poor fruit and vegetable consumption, a lack of fibre and eating a lot of red and processed meat – as well as a lack of physical activity, Bauld says there are over 50,000 preventable cases of cancer in the UK every year.

And while the connection between smoking and cancer is well known, there is much less awareness about the significant link between being overweight and cancer.

Research by Cancer Research UK last year found that just one in four people knew of a link between obesity and cancer, and those in lower socio-economic groups were even less likely to be aware of it.

It’s now a serious issue, given the increasing rates of obesity in Scotland. They have doubled over the last 10 to 15 years and there has been no reduction in the number of people who are overweight and obese overall, with around 65 per cent of adult Scots overweight.

While we don’t yet have long-term studies examining whether childhood obesity causes cancer as an adult, Bauld points out that we do know that those who are overweight as children are far more likely to continue to be overweight as adults.

But the distribution of obesity, and therefore the cancer risk, is not spread evenly across the population, with those in deprived areas particularly at risk.

Bauld says: “The gradient is very clear. It’s the same gradient you have for smoking, so you’re significantly more likely to be overweight or obese if you live in the 20 per cent most deprived communities in Scotland compared to the 20 per cent most affluent, and it goes up by the level of deprivation in the community.

“So it’s like a slide, basically, going upwards, and it’s the case for obesity and it’s the case for severe obesity and those patterns exist for men, they exist for women and they exist for children by deprivation.”

by Tom Freeman

Obesity causes cancer

But while we know there is an issue, resolving it is complicated.

David Blane, a ‘Deep End’ GP working in Maryhill, who is currently completing a PhD on obesity and is the GP representative on Obesity Action Scotland, maintains that the issues are complex.

He says: “Obesity is a function of a combination of your eating behaviours and your activity behaviours and those things don’t happen in isolation, they’re very much shaped by your context.

That can be both your genetic context but also your family context, your community context, your education levels, your stress levels, your form of employment or lack of employment will have an impact on those behaviours.

“Some of these behaviours you need money to do. So, for instance, if you’re well-off, you can afford to get a gym membership or you can afford to eat healthy meals at will, whereas for some living in poverty, eating healthy foods can be more challenging or being more physically active can be more challenging.”

But he suggests it’s not only an issue of what money can buy you, but also what stresses or opportunities there are in your area.

“You’ve got individual factors like people’s sense of control, their sense of a future – is it worth my while investing in difficult behaviour change? – their sense of social support, what are the norms for people in their area, is everyone in your family overweight or obese, does everyone have fast food, TV dinners, not interested in exercise.

“If that’s the norm for your family and your social network, then it’s very difficult to buck that trend.”

The Scottish Government is currently consulting on its diet and obesity strategy, which includes proposals to restrict the marketing of foods high in salt, sugar and fat and a £40m investment in supported weight management programmes.

Both Blane and Bauld agree that the key to seeing some improvement is about making healthy choices, easy choices.

In terms of whether population-wide or targeted measures are best, Blane suggests both.

He explains: “I think from a public health point of view, the blanket or population-level are most effective and will generally have some effect on health inequalities as well.

“The targeted stuff – so targeting interventions at specific groups – can make a difference as well, but I think it again comes back to the idea that at an individual level, behaviour change is very difficult, so in a sense, making changes to the environment for everyone is much easier.”

Bauld says: “The crucial thing they need to do is change the food environment and there’s a number of things you can do to change the food environment: you can make healthy products a lot more affordable and unhealthy products more expensive, and you could also tackle the promotion of these products, the advertising and marketing of these products.”

Bauld particularly welcomes the action on price promotions, especially multibuy offers of unhealthy food in a retail environment.

She is also enthusiastic about proposals for a much improved weight management service.

Regarding price promotions, she says: “For me, that’s not like a silver bullet, it’s not going to solve the problem, but it’s a very important first step to dealing with price and promotion, which we know drive consumption.”

Blane says: “I think the strategy looks very good. What they’ve set out in terms of the public health measures – going along with the idea of the UK sugar tax, but also mentioning they’re restricting advertising and the price promotions, the marketing side of things – I think these are really positive proposals.”

Overall, Bauld is positive about the Scottish Government’s strategy: “They’re making a really good start and it’s a hugely more ambitious programme of work than what’s being proposed at the UK level.

“We were really pleased to see the strategy released for consultation, some really good policies in here. Now we just need to gather the support and also try to be aware of the fact that not all stakeholders are going to want to see those changes.”

Clearly, there’s a very long way to go, with two-thirds of the adult population currently overweight, and those in more deprived areas particularly affected, but many of the efforts to tackle obesity are modelled on successful campaigns to reduce smoking, which have included gradually removing tobacco advertising, introducing plain packaging, rice rises and banning smoking in public places.

The progress that has been made there is dramatic. In the 1950s, up to 80 per cent of men smoked and now it’s 22 per cent.

Between 2003 and 2016, the percentage of adults smoking in Scotland dropped from 31 per cent to 21 per cent. In more deprived areas, even 15 to 20 years ago 40 per cent of the adult population smoked.

Now that has dropped to 27 per cent. In adopting some of the measures that have proved successful, perhaps such dramatic drops will also be seen for obesity rates in future decades.