Why are more adults being diagnosed with cancer before they reach middle age? A new study points to a possible clue inside the body itself. People born in more recent decades may be showing signs of faster biological aging, even when their actual ages are the same.
The research links a wider gap between biological age and chronological age with a higher risk of solid cancers diagnosed before 55. The signal was strongest for lung, gastrointestinal, and uterine cancers, but the findings do not show that accelerated aging directly causes cancer.
Biological age is not birthday age
Chronological age is the number on a birth certificate. Biological age is an estimate of how old the body appears based on blood chemistry, metabolism, proteins, and the condition of organs. Two people can both be 40 while their bodies show very different levels of wear.
The researchers used several aging clocks, including a measure called PhenoAge. It combines nine common blood markers, such as albumin and creatinine, to estimate whether the body looks younger or older than expected. Think of it as reading the dashboard, not just checking the car’s model year.
A gap between generations
First author Ruiyi Tian worked with colleagues at Washington University School of Medicine in St. Louis, where senior author Yin Cao described the aim this way: “our ultimate goal is to decode how modern environments become biologically embedded to drive cancer risk.”
The team analyzed more than 154,000 people in the UK Biobank and 10,262 participants in the National Institutes of Health’s All of Us Research Program. In the British data, those born from 1965 through 1974 had a 23% shift on the standardized aging scale compared with those born from 1950 through 1954.
The U.S. pattern was even larger. People born from 1990 through 1999 were nearly one full standardized step higher than those born from 1965 through 1969. That does not mean they were 92% older, only that their blood-based profiles looked further ahead of their calendar age.
Cancer risk moved with the clock
The British cancer analysis followed 148,317 adults for almost 954,000 combined years. For each standard step upward in the PhenoAge gap, the risk of an early-onset solid cancer was 8% higher. People in the highest third of accelerated aging had a 15% higher risk than those in the lowest third.
The organ findings were more specific. An older-looking immune system was associated with an 89% higher risk of early-onset lung cancer for each standard step, while older-looking fat tissue was linked to a 60% higher risk of early-onset colorectal cancer.
The U.S. group showed the same general direction, with a 22% higher risk per standard step. Still, that analysis included only 104 early-onset cancer cases, so the estimate is less certain than the larger British result.
The wider cancer picture
The trend is serious, but it is not the same for every cancer. A 2025 National Cancer Institute analysis found that 14 cancer types rose in at least one U.S. age group under 50 from 2010 through 2019, while 19 types fell.
The overall cancer rate and overall cancer death rate did not increase in younger adults during that period.
Breast, colorectal, kidney, and uterine cancers accounted for more than 80% of the additional early-onset cases estimated for 2019. Definitions also vary. The new biological-aging study used diagnosis before 55, while many national reports use diagnosis before 50.
What might speed the clock
The study did not identify one culprit. Instead, biological age may act like a receipt for many exposures collected over time, including excess body weight, metabolic problems, poor diet, long periods of sitting, disrupted sleep cycles, air pollution, and environmental chemicals.
A late work shift, a polluted commute, or years of meals chosen in a rush may sound ordinary. None was proven to cause cancer in this research, and individual choices are only part of the picture. Broader social and economic conditions may also shape the body’s aging signals.
Important limits
This was an observational study, which means it can find patterns but cannot prove cause and effect. The main estimates relied on baseline blood measurements, more like a photograph than a movie. The British sample was also 92% white, although the smaller U.S. group was more diverse.
John Riches, a clinical reader at Barts Cancer Institute, said in comments shared by the Science Media Centre that the study “does not show” direct causation.
Faster biological aging and cancer could share the same underlying drivers, or aging changes could play a more direct role. Researchers still need repeated measurements and larger studies to sort that out.
For now, a biological-aging score is a research measure, not a validated stand-alone cancer test. It may eventually help doctors identify risk earlier, but that promise needs careful validation.
The official study was published on June 22, 2026, in Nature Medicine.
