Scientists may have identified one reason why early-onset cancer diagnoses — cases involving people under 50 — are becoming more common.
Although cancer is often seen as an illness linked to older age, diagnoses among younger adults have been climbing steadily in recent decades.
In fact, global analyses suggest early-onset cancers have risen sharply since 1990, with incidence increasing by nearly 80 percent worldwide by 2019.
That has made it increasingly important to understand what could be contributing to the rise in early-onset cases.
One recent study from researchers at WashU Medicine points to a possible factor: younger generations may be experiencing faster biological aging than the generations before them.
The research, published in Nature Medicine, examined data from more than 154,000 people in the UK Biobank as well as more than 10,000 participants in the US All of Us Research Program.
Their analysis found that accelerated biological aging was associated with a higher risk of developing multiple cancers earlier in life, especially early-onset lung, gastrointestinal and uterine cancers.
To measure biological age, the researchers used blood samples together with other health information to assess whether someone’s body appeared to be aging faster than expected for their actual age.
They also used an algorithm called PhenoAge, which draws on blood-test markers to reflect a range of health indicators, including inflammation and immune function.
In the study, people born between 1965 and 1974 had a 23 percent higher standardized PhenoAge-defined age gap than those born between 1950 and 1954, suggesting later birth cohorts were biologically older than expected for their chronological age.
Dr Yin Cao, associate professor of surgery and of medicine at Washington University School of Medicine, said:
“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 researchers also found that immune-system aging appeared to be linked to early-onset lung cancer, while aging in adipose tissue was connected to early-onset colorectal cancer.
In the UK Biobank analysis, each standard-deviation increase in the PhenoAge-defined age gap was associated with an 8 percent higher risk of early-onset solid cancers overall, with the strongest associations seen for lung, gastrointestinal and uterine cancers. In the US cohort, the same direction of association was seen, although the number of cancer cases was smaller.
Importantly, the study was observational, so it cannot prove that faster biological aging directly causes cancer. It does, however, add to a growing body of evidence suggesting that early-onset cancer may be driven by a combination of long-term exposures, lifestyle factors and broader changes in health across generations.
That broader picture matters because doctors and researchers have increasingly pointed to obesity, sedentary behaviour, metabolic disease, alcohol use, smoking and other environmental exposures as possible contributors to the rise in cancers diagnosed before age 50.
Dr David Scott, who played a key role in collecting the research, quipped:
“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.
“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.”
The researchers say the next step is to better understand which exposures are most strongly linked to accelerated aging, and whether slowing biological aging could one day help reduce the risk of early-onset cancer.