Global cancer diagnoses in patients under the age of 50 rose by 24 per cent between 1990 and 2019, and the trend is continuing, according to research published in Nature Medicine. The study, which analysed data from more than 154,000 individuals in the UK Biobank and over 10,000 participants from the US National Institutes of Health’s All of Us Research Program, suggests that accelerated biological ageing may hold the key to understanding why younger generations are being diagnosed with cancer at higher rates than previous ones.
The rise in early-onset cancers
In the UK alone, cancer incidence rates among people aged 25 to 49 increased by 24 per cent between 1995 and 2019 — a sharper rise than in any other age group, and more than double the rate of increase seen in those over 75. Approximately 35,000 under-50s are diagnosed with cancer in the UK each year, equivalent to nearly 100 young people every day.
The research, part of a global initiative called Cancer Grand Challenges — jointly funded by Cancer Research UK and the American National Cancer Institute — focused on early-onset cancers, generally defined in the field as those diagnosed at age 55 or younger. The team behind the study, known as Team PROSPECT, is specifically investigating the origins of early-onset colorectal cancer, which has seen incidence rates in under-50s in the UK rise by roughly 50 per cent since the mid-1990s. More than 2,400 people under 50 are now diagnosed with bowel cancer annually in the UK, with three out of five cases detected at a late stage.
Other cancers showing notable increases in younger adults include ovarian and endometrial cancers. In England, endometrial, kidney, pancreatic, multiple myeloma and thyroid cancers have increased significantly faster in younger women than in older women. Researchers stress that while the findings show a strong association between accelerated biological ageing and early-onset cancer, they do not definitively prove causation. “Right now, we don’t have a definitive answer to what’s driving the rise of early-onset cancers around the world, but studies like this are helping us piece together the bigger picture,” said Dr David Scott, who worked on the research.
What is biological age?
Biological age differs from chronological age and reflects how well the body is functioning at a cellular and molecular level — a concept the researchers argue is central to understanding the shifting cancer landscape. To measure it, the scientists used an established algorithm called PhenoAge, which combines nine routine blood test results that capture indicators such as blood sugar control, inflammation and immune system function. By analysing blood samples and other health data, they estimated whether a person’s body appeared “older” or “younger” than expected for their age.
Dr Yin Cao, associate professor of surgery and of medicine at Washington University School of Medicine, explained: “Biological ageing isn’t just about the number of birthdays you’ve had — it reflects wear and tear happening inside the body at a cellular and molecular level. This can include changes that affect how cells and tissues function, such as chronic inflammation, weakening of the immune system and damage building up in cells over time.” The study found that accelerated biological ageing is associated with a higher risk of developing multiple cancers earlier in life, specifically early-onset lung cancer, colorectal cancer and uterine cancer.
Importantly, the researchers also looked beyond whole-body ageing to organ-specific measures, using proteomics approaches. They found that an older-appearing immune system was linked to early-onset lung cancer, while accelerated ageing of adipose tissue was tied to early-onset colorectal cancer. “These findings suggest that accelerated biological ageing could reflect the combined impact of our lifestyles and environments on the body over time, potentially helping explain why some cancers are appearing earlier in younger generations,” added Dr David Scott.
The UK Biobank, a major resource housing deep phenotyping and genomic data from over 500,000 UK adults, provided the bulk of the data. However, researchers note that cancer incidence in Biobank participants is about 10 per cent lower overall than in the general population, with most cancers showing lower incidence that increases with deprivation — a factor that may influence the generalisability of the results.
Lifestyle and environmental factors
Several factors are believed to drive accelerated biological ageing, which in turn may raise cancer risk. “Wear and tear markers” such as chronic inflammation and DNA damage can be caused by unhealthy lifestyles, including poor diet, lack of exercise, smoking, alcohol consumption and disrupted sleep patterns, as well as by exposure to environmental pollutants. Rising obesity levels are identified as a primary driver for several cancers showing increased rates in younger people in England, linked to 10 out of 11 cancers with rising incidence. Yet obesity alone does not explain the full picture, suggesting other unknown causes are at play.
Genetics also contribute to ageing rates — approximately 20 to 30 per cent of ageing factors are hereditary — while early-life exposures, such as antibiotic use, maternal obesity and birth weight, may play a role. Chronic inflammation is considered a key marker of the wear and tear that accelerates biological ageing. Dr Jyoti Nangalia, Group Leader at the Wellcome Sanger Institute, noted that measurements of biological age likely capture the combined effects of genetics, lifestyle and environment, and further research is needed to understand precisely what these measurements indicate.
Dr John Riches, Clinical Reader at Barts Cancer Institute, commented that the study offers “an important new clue” as to why more cancers are being diagnosed in younger adults, but emphasised that it does not prove direct causation. The ultimate goal of Team PROSPECT, funded by Cancer Grand Challenges, is to decode how modern environments become biologically embedded to drive cancer risk, potentially enabling personalised prevention strategies rather than broad recommendations. There is also concern that people under 50 diagnosed with bowel cancer are not being consistently tested for Lynch syndrome, a genetic condition that significantly increases the risk of bowel and other cancers — another piece of a puzzle that researchers say is far from solved.