Millennials may look younger than earlier generations, but biologically they are aging faster, according to a new study. The research also found that their risk of developing cancer at an early age is rising along with it.
People Born in the 1990s Had Older Bodies at the Same Age
According to a paper by researchers at the Washington University School of Medicine, recently published in the international journal Nature Medicine, people born between 1990 and 1999 had a higher biological age at the same chronological age than those born between 1965 and 1969.
Biological age quantifies how much the body has actually aged, based on blood tests and various physical indicators. Using the "PhenoAge" metric applied by the researchers, the biological aging level of those born in the 1990s was 92% higher than that of earlier generations.
This means that while the spread of sunscreen use and skincare culture makes people in their 30s and 40s appear less aged on the outside, the aging clock inside the body is running much faster. This trend was more pronounced in men than in women.
What the researchers found particularly notable was the link between the pace of biological aging and early-onset cancer. The older the body was relative to actual age, the higher the likelihood of developing cancers such as lung, gastrointestinal, colon, and uterine cancer. Aging speed also varied by organ as well as across the body as a whole. When the immune system was older than actual age, the risk of early-onset lung cancer rose, and aging of fat tissue was associated with early-onset colon cancer.
Cancer Patients Under 50 Rose 24% Over 30 Years, and Korea Is No Exception
The rise in young cancer patients is a trend confirmed worldwide. Cancer patients under the age of 50 increased by 24% between 1990 and 2019. Colon and uterine cancer, in particular, are rising steeply among younger generations.
In this study, those born in the 1990s were calculated to have more than four times the risk of early-onset colon cancer than those born in the 1960s. People born around 1985 had roughly twice the uterine cancer risk compared with those born before 1950.
The situation in Korea is not much different. According to data from the Health Insurance Review and Assessment Service, the number of colon cancer patients in their 20s and 30s rose from 3,633 in 2020 to 6,599 in 2024, a surge of 81.6% in four years.
The researchers pointed to factors such as the early onset of obesity, diabetes, and stroke, and the falling age of puberty onset as the background to these changes. They explained that these factors may work as a common mechanism that accelerates physical aging while simultaneously raising cancer risk.
However, the researchers cautioned that the cause of the rise in cancer among younger generations has not yet been clearly identified. Research so far has gone no further than offering the observation that environmental changes, lifestyle habits, and social factors in modern society may accelerate biological aging, which in turn could lead to an increased cancer risk.
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