Cancer diagnoses among people under the age of 50 have risen by 24 per cent worldwide over the past three decades, with new research suggesting that accelerated biological ageing may be a key factor behind the trend.
The accelerating rise in early-onset cancers
Between 1990 and 2019, the incidence of cancers diagnosed in patients aged under 50 increased by a quarter globally, according to the study published in Nature Medicine. In the United Kingdom alone, cancer rates in 25 to 49-year-olds climbed by 24 per cent between 1995 and 2019, meaning roughly 100 younger adults were diagnosed every day between 2017 and 2019. The incidence rate for this age group rose from 132.9 per 100,000 people in 1995 to 164.6 in 2019 — a percentage increase more than double that seen in people over 75.
In the United States, the picture is similarly stark. From 2010 to 2019, the incidence of 14 cancer types increased among people under 50, with nine of those also rising in older age groups. The largest absolute increases in early-onset cancers in the US were for female breast cancer (roughly 4,800 additional cases in 2019), followed by colorectal (2,100), kidney (1,800) and uterine cancers (1,200). Notably, while overall cancer deaths in young Americans have fallen by 44 per cent since 1990, colorectal cancer mortality is the only major cancer in which deaths are rising in people under 50 — increasing by about 1 per cent per year since 2005. Colorectal cancer is now the leading cause of cancer death in that age group in the US.
Biological ageing: a new lens on early cancer
Researchers analysed data from two large cohorts — the UK Biobank, comprising 154,169 individuals, and the US All of Us Research Program, with 10,262 participants — to investigate whether the rate at which the body ages at a cellular and molecular level could explain the rise in early-onset cancers. Their findings suggest 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.
Biological age differs fundamentally from chronological age. While chronological age counts the years since birth, biological age reflects how well the body is actually functioning and can be influenced by factors such as diet, exercise, environment and overall health. To measure it, the researchers used an established algorithm called PhenoAge, developed at Yale School of Medicine, which combines the results of nine routine blood tests. These biomarkers reflect key physiological systems, including blood sugar control, inflammation, immune function, liver and kidney function, and cellular ageing. The algorithm estimates whether a person’s body appears “older” or “younger” than expected for their age.
Dr Yin Cao, associate professor of surgery and of medicine at Washington University School of Medicine and a co-team lead for the study, 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 also observed a clear “birth cohort effect,” indicating that younger generations appear to be ageing faster biologically. Among UK participants, those born between 1965 and 1974 showed approximately 23 per cent higher levels of accelerated biological ageing compared with those born in the early 1950s. In the US cohort, the trend was even more pronounced: individuals born between 1990 and 1999 displayed systemic ageing that was 92 per cent of one standard deviation higher than those born between 1965 and 1969. This advanced ageing in younger groups corresponded to an increased risk of early-onset solid cancers.
Beyond whole-body ageing, the team looked into organ-specific measures using proteomics approaches. They found links between immune system ageing and early-onset lung cancer, and between adipose tissue (fat) ageing and early-onset colorectal cancer. Dr David Scott, who worked on the research, said: “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, showing that cancer may be influenced not just by changes inside individual cells, but by wider changes happening across the body as a whole.”
Lifestyle and environmental factors at play
Researchers point out that these “wear and tear markers” — such as inflammation and DNA damage — can be caused by unhealthy lifestyles or exposure to pollutants. In the UK, the 24 per cent rise in cancer diagnoses among under-50s has been linked to soaring obesity levels, cheap junk food and inactivity. Research in England found that obesity was linked to 10 out of 11 cancers rising among younger people. Ultra-processed food consumption has also been specifically linked to an increased risk of early-onset colorectal cancer precursors.
“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,” said Dr Scott.
The study is part of Team PROSPECT, a global initiative funded by Cancer Grand Challenges — a joint venture of Cancer Research UK and the US National Cancer Institute, with additional support from the Bowelbabe Fund for Cancer Research UK and the French National Cancer Institute. The researchers caution that the study does not prove that faster biological ageing directly causes cancer, but it adds weight to the understanding that cancer is a systemic disease influenced by the body’s broader biology. While approximately 9 in 10 cancer cases still occur in people over 50, the upward trend among younger adults is drawing urgent attention from scientists seeking to identify higher-risk individuals earlier. In England alone, between 2001 and 2019, incidences of 16 out of 22 cancers in younger women and 11 out of 21 cancers in younger men increased significantly, with bowel and ovarian cancers rising only in the under-50 age group.
