Rising rates of early-onset bowel cancer are a “global phenomenon”, and some of the steepest increases are happening in England, according to a majornew paper published today inThe Lancet Oncology.
Using World Health Organization (WHO) data for the years to 2017, an American Cancer Society-led research team found increasing rates of bowel (or colorectal) cancer in younger adults in 27 out of the 50 countries and territories included in their study. For the first time, these include parts of Latin America, the Caribbean, Eastern Europe and Asia.
“Early-onset colorectal cancer is a growing global phenomenon,” explained Dr Yin Cao from Washington University in St Louis, whose work on the study we supported throughCancer Grand Challenges. “But, at the same time, it is still rare. In the UK, the incidence of colorectal cancer in under-50s is just one-tenth of the incidence in older populations. Even though it is increasing, I don’t think people should be scared.”
The analysis suggests that England experienced the fourth fastest (3.6% per year) rise in the rate of early-onset bowel cancer in the decade to 2017, behind only New Zealand, Chile and Puerto Rico. This increase was not matched in the other devolved nations of the UK.
As risk factors and diagnostic pathways are similar across UK countries, it’s likely this variation is linked to population differences. Because the overall number of diagnoses is so much lower in Scotland, Wales and Northern Ireland, small fluctuations can make it much harder to establish a trend over time.
“More research is needed to understand whether there are genuine differences between the nations, and how to address them,” said Katrina Brown, a a senior cancer intelligence manager here at Cancer Research UK.
“The important thing to focus on is that the rate of colorectal cancer in 25 to 49-year-olds is the same across the UK at this point,” added Dr Cao.
Of all the countries and territories included in the study, the UK nations rank 16th to 19th for the overall rate of early-onset bowel cancer. The rate is highest in Australia, Puerto Rico, New Zealand, the US, and South Korea.
A global trend with local differences
Crucially, the new study is the first to track a rise in early-onset bowel cancer outside high-income western countries.
In the paper, the researchers note that, in many of the newly identified countries, increases in early-onset bowel cancer coincide with or follow on from periods of economic development. That suggests they could be linked to rapid changes in lifestyle and diet.
These changes may have happened earlier and more gradually in countries like the UK and the US, wherethe increases in early-onset bowel cancer rates had already been documented.
There are further layers of complexity there, too. The last decade of WHO data shows that in 14 primarily high-income countries, bowel cancer rates increased in 25 to 49-year-olds while stabilising in older age groups.
These changes could be linked to changes in how and when bowel cancer is diagnosed, but there’s a lot more we need to find out. Dr Cao believes the differences underscore the need to identify emerging and novel risk factors for early-onset bowel cancers, which might mark them out from bowel cancers that start later in life.
“With this rigorous analysis leveraging WHO data, we’ve been able to make direct comparisons across countries and deepen our understanding of what’s going on across the globe,” she added. “This will be the new global map for this topic.”
Taking on early-onset bowel cancer
As the co-lead for Cancer Grand Challenges teamPROSPECT, Dr Cao is already using the map to plot a path forward.
In March 2024, Cancer Grand Challengesawarded PROSPECT up to £20m to investigate the underlying causes and mechanisms driving the rise in early-onset bowel cancer. From there, the team are aiming to develop and test innovative strategies to help prevent the disease in future generations.
“This paper really highlights some of the regional differences and sex differences that we’ve been funded to look into,” Dr Cao explained.
“For example, in England, Scotland and some other countries, we documented a faster increase in women than in men, which has not been really revealed previously.
“PROSPECT and other research teams around the world are working together to understand the underlying causes so that we can develop intervention strategies. We’re at the early stages of harmonising cohorts and biobanks across the globe, but we’re extremely excited to leverage some of the UK’s powerful data resources to really understand what’s going on in close detail.
“We are also fortunate to have support from a global team of patient advocates on this journey to shape the future.”
Michelle Mitchell, our chief executive, also highlighted the importance of continuing to support research into the causes of early-onset bowel cancer.
“A cancer diagnosis at any age has a huge impact on patients and their families – so while it’s important to note that rates in younger adults are still very low compared to people over 50, we need to understand what’s causing this trend,” she said.