Rising cancer incidence in younger adults: what is going on?
About 3 mins
Growing numbers of adults under 50 years are experiencing a cancer diagnosis (often known as early or young-onset cancer). Cancer can affect people at any age, but science has long established that incidence rates rise over the life course. In the UK in 2017–19, over a third of cases (36%) were diagnosed in people aged 75 years and older; and just over half (54%) in people aged 50–74 years. Emerging research is complicating these patterns, however, by suggesting that cancer risk among younger adults is increasing. Mainstream media coverage has followed.
This raises some big questions, namely: what factors could be contributing to rising incidence at earlier ages? What should be done to mitigate these increases? And how can health services and national policymakers respond?
What the evidence is saying about cancer rates in younger adults
This is a developing field, but evidence is mounting that rates of young-onset cancer incidence are increasing, particularly in high-income countries in the global north. A study looking at global trends focusing on 29 types of cancer in people aged 14–49 years, found incidence of these cancers increased by around 79% between 1990 and 2019, with around 3.3 million cases globally in 2019 and countries in more economically developed regions particularly affected.
In the UK, cancer incidence rates among people aged 25–49 years increased by roughly 22% between 1993–95 and 2016–18 (while incidence rates among those aged 75 years and older increased by around 9%). Analysis in other developed economies – such as the US and Australia – have shown upward trends too. Things seem to point to the early 1990s as an inflection point when rates began to increase in younger people, and it appears there is a cohort effect emerging with the risk rising in successive generations (for at least some cancer types).
So what could account for the uptick? Much research is being devoted to this question, which the Health Foundation’s September podcast explores in more detail. Cancer is a complex phenomenon and there are a number of hypotheses. In simple terms, these can be thought of in two groups: first, individual risk factors and second, theories that focus on wider environmental exposures.
The first group centres around known risk factors for cancer – such as tobacco, alcohol, obesity, physical inactivity, diets high in processed foods – and suggests that modern lifestyles are exposing young people to a combination of these risk factors and driving up cancer risk. The fact rates of cancers of the digestive system – such as stomach, bowel and rectal – are trending upward is drawing attention towards the role of contemporary diets. Changes in reproductive patterns may be playing a role as well: women in high-income countries are generally having fewer children and later in life (time spent pregnant and breast feeding has been found to be protective against some cancer types).
A second cluster of explanatory theories point more to possible environmental influences. Some research has looked at widespread exposure to microplastics and polyfluoroalkyl substances (also known as ‘forever chemicals’). Others are exploring these in conjunction with the gut microbiome (the bacteria and microbes that inhabit the human digestive tract) and investigating whether external exposures are affecting it in ways that increase cancer risk. Precisely how these exposures could lead to cancer is still subject to research, but some suggest they trigger an inflammatory response inside the body that affects cancer risk.
What should this emerging evidence mean for cancer policy and practice?
At this point, there’s no playbook for the right way forward. But three areas stand out where decisions are likely to be needed from those leading local services and shaping national policy:
- More research will be paramount. Key challenges include better understanding the biological pathways of young-onset cancers, disentangling the factors that may be contributing and clarifying whether certain groups of people or ethnicities are particularly at risk. Linking large datasets – which the NHS is favourably positioned to support – could present opportunities to explore these questions in novel ways.
- For health services, there are questions about how diagnostic and delivery models may need to adapt. This includes adapting to changing patient populations in the delivery of cancer care, improving detection of cancer in younger adults including in primary care, and exploring opportunities to leverage technologies, such as AI, to spot patterns in large bodies of data.
- For policymakers, there are questions about how national strategies to prevent and detect cancer will need to change. For example, support for novel diagnostic approaches and preventative measures to address established risk factors will need to be responsive to emerging evidence. Cancer increasingly affecting working-age adults will also raise questions about how health and welfare services can support people to live well with cancer and continue to be economically active where possible.
Responding effectively to these trends – and navigating a rapidly developing evidence base – will demand a strategic approach. Yet England lacks a holistic national strategy for cancer care and policy (beyond the national ambitions for cancer outlined in the NHS Long Term Plan, which included a focus on improving early diagnosis). The Labour government has said it plans to renew the NHS – which it declared ‘broken’ – by developing a 10-year plan. This presents an opportunity to address cancer’s place in health policy in England.
This plan faces two big challenges in charting a direction for cancer care in England: first, setting out how operational performance of cancer services can be restored in the near term (some cancer waiting-time standards have been routinely missed for a number of years); and second, expanding services’ capacity to diagnose and treat rising numbers of cancer cases over the coming decades (projections suggest over 500,000 cases a year in the UK by 2038–40). To those, a third challenge can be added: outlining a framework to research, diagnose and address rising cancer incidence in younger adults.