When it comes to diagnosing cancers early, screening is our best available tool.
Cancer screening involves testing for early signs of cancer in people without symptoms. It can help spot cancers at an early stage, when treatment is more likely to be successful, or in some cases prevent cancer from developing the first place.
In the UK, there are three national screening programmes: bowel, breast and cervical.
Screening for bowel cancer is offered to everyone between the ages of 60 and 74 in England, Wales and Northern Ireland, or 50 and 74 in Scotland.
It’s done through a test that you do at home, called a faecal immunochemical test, or FIT, that looks for tiny traces of blood in your poo. These tests are sent to everyone in the eligible population every two years.
Bowel cancer is the 4th most common cancer and the 2nd most common cause of cancer death in the UK.
The incidence of bowel cancer, and mortality from it, is higher in socioeconomically deprived communities. This is partly due to lower rates of screening uptake, which means that people in these groups don’t benefit from potential early diagnosis.
Therefore, if we can find successful interventions that help to increase participation in screening programmes amongst lower income groups, we may be able to reduce the health inequalities that exist in bowel cancer outcomes.
And researchers at the University of Sheffield are trying to do exactly that.
Building a model
There are many factors that lead to inequalities in bowel cancer, including differences in underlying health conditions and treatment. Although screening is just a small part of the picture, it’s vital the programme works for everyone.
Chloe Thomas, lead researcher from University of Sheffield.
Their research, funded by us and published today in Preventative Medicine, modelled the impact of screening on bowel cancer inequalities in England and then compared four different intervention strategies for increasing participation.
Modelling studies allow us to simulate a variety of scenarios over long periods of time, even lifetimes, in a computer programme.
They can also take into account factors that might change with a person’s age, like BMI, alcohol consumption and physical activity, and consider how those changes might impact the outcome being investigated.
Think of it as the equivalent of running multiple different experiments over the course of a person’s lifetime all at once.
Therefore, whilst this isn’t data from the real world, it gives us a way of making estimations where real world data could take decades, or would even be impossible, to collect in a traditional experiment setting.
Through their model, they aimed to determine which of the four methods was the most cost-effective alongside reducing screening-based inequalities.
The scenarios the model simulated were 1) annual re-invitation of screening non-participants; 2) a national media advertising campaign; 3) text message reminders for non-participants; 4) health promotion in deprived populations.
The model population was based on real data from the 2014 Health Survey for England, an annual survey designed to provide a snapshot of the nation’s health.
The first part of their study compared the incidence and mortality from bowel cancer with FIT, the screening method currently used in the UK, vs no screening at all.
As expected, FIT screening was found to be both highly cost-effective and effective at reducing bowel cancer mortality. However, these benefits were not spread equally across the eligible population, with FIT screening alone even exacerbating socioeconomic inequalities due to low participation in more deprived groups.
And to make matters worse, if a wider age group was screened, for example lowering the initial screening age to 50, as is being implemented in England, this only serves to widen the inequality gap.
Therefore, whilst screening is an extremely effective method of reducing bowel cancer mortality overall, without strategies to mitigate this inequality, it doesn’t benefit everyone.
However, one of the interventions tested in the model, annual re-invitation of screening non-participants, was found to be highly effective, estimated to prevent over 11,000 bowel cancer deaths over the lifetime of the current English population aged 50-74.
Crucially, more deaths were prevented in the most deprived groups, meaning that inviting people who haven’t participated in bowel screening every year rather than every two years can have a big impact on reducing inequalities.
“This is the first time anyone has looked at how screening interventions can impact inequalities,” says Thomas.
“We believe we’ve identified a cost-effective way to increase uptake and reduce mortality across all groups. But this was based on modelling and real-world data is needed to confirm our conclusions.
“The next step would be to pilot an annual re-invitation programme within parts of the NHS.”
On her 60th birthday, Anne received a home test kit in the post. She wasn’t going to do it but thought ‘why not?’ and sent it back. Working as a teaching assistant at the time, she joked about there being a cardboard box in the classroom containing her poo.
A few days later, she received a letter asking her to go to hospital for more tests. The sample she sent in had shown abnormalities.
An examination by camera found a growth, and she was booked into surgery after a planned holiday.
Anne was told that the tumour was just starting to break through the outer side of the bowel and that she was lucky she hadn’t left it any longer. If she had, the cancer likely would have spread.
She had part of her bowel removed and chemotherapy after that. Now, she’s recovered and is encouraging others to take up screening.
“I can’t imagine how different my life would be if I hadn’t decided to send my kit back. Yes, it’s a bit odd and embarrassing to collect your poo, but I’m proof that it saves lives. I had no symptoms and didn’t feel unwell, yet I was told my cancer was growing and had nearly spread.
“And it’s so much easier to get screened now than when I did it. You don’t need multiple samples anymore. Just one poo. Don’t store your stool – when you receive a home test kit send it back.”
Making a real-world change
Making these changes to the screening programme might not be easy.
Annual re-invitation will require a big investment to make and send out the additional FIT kits. It will also require more colonoscopy resource than the current programme for those that need further testing.
However, the model found that annual re-invitation was highly effective and cost-effective, more so than any other trialled intervention, and had a significant impact in reducing inequalities.
What’s more, we know from previous experience that changes to a screening programme can have a big impact on participation.
Before June 2019, England used a test called the guaiac Faecal Occult Blood Test (gFOBT) for bowel cancer screening, which required multiple samples taken from two different poos.
The FIT has made bowel cancer screening simpler, as this test only requires one sample from one poo. Since its introduction, bowel screening uptake has steadily increased.
From 2009 to 2019, when the gFOBT test was used, screening uptake hovered between 55% and 60%, it now sits at 71%, as measured in 2020/21.
Now, if the NHS can pilot an annual re-invitation scheme to get real world data, that figure could further increase, with a particular impact on socioeconomically deprived groups, catching more cancers early and ultimately saving lives.
“Screening is an effective way of catching cancer early and saving lives, but not everyone engages equally, and this contributes to health inequalities across the UK,” says Michelle Mitchell, our chief executive officer.
“Addressing health disparities is critical to achieving the Government’s early diagnosis targets and saving lives.
“We urge Government to invest in a re-invitation pilot as part of its upcoming 10-Year Cancer Plan. We need a cancer plan for all – and bold action, such as this, will benefit generations to come.”