When someone asks you your age, you probably know what to say. You could use years, months or seconds – or maybe tell them which Doctor from Doctor Who you grew up with. Regardless of how you refer to your age, you’ll most likely be describing how much time has passed since you were born. 

Scientists who study ageing would call this your “chronological age”. But they also have other ways of measuring how old you might be. They can look for biological clues (biomarkers) hidden in people’s bodies to understand how wear and tear has built up in their cells over time. This is called “biological age,” and it’s much more than a number. 

Cancer Grand Challenges team PROSPECT has been investigating whether biological ageing could be a tool to understand why more people under the age of 50 are developing cancer.  

In their latest study, the team compared how over 160,000 people across the UK and US are ageing biologically. And their results suggest that younger generations may be ageing faster than older ones, which could be linked to a higher risk of developing certain cancers earlier in life.

The study reported trends rather than causes, so it can’t prove a direct link between faster biological ageing and cancer. But it gives scientists another way to think about cancer prevention, one that looks beyond the specific area where a cancer might start. By focusing on ageing, they can look for biological warning signs throughout the body. One day, this could become a way to detect the disease sooner or even to understand how to stop it from developing.

What is biological ageing? 

When scientists talk about biological ageing, they’re referring to the changes that occur across cells, tissues and organs over time. 

“Biological age reflects how the body is functioning beneath the surface, so two people of the same chronological age can have very different biological profiles,” explains Riuyi Tian, lead author from Washington University in St Louis.

The factors that influence biological ageing are still being uncovered, but so far, research suggests that diet, exercise, sleep and the environment may all play a part. As we get older, they can lead to changes in the body like chronic inflammation and weakening of the immune system.

Since biological ageing can change how the body works over time, this led Dr Yin Cao, co-lead of PROSPECT and associate professor at Washington University in St Louis, to question how it could be used to understand cancer risk.

“As we increasingly recognise cancers as systemic diseases, we are wondering: can we leverage biomarkers, such as biological ageing, to help us understand the different factors that impact the risk of early-onset cancers?”

Reading the biological clock 

The team set out to understand how these biological changes varied across different generations, especially in people who are currently under 50.

They reviewed the electronic health records of more than 164,000 people – roughly 154,000 from the UK and 10,000 from the US. They looked at their blood tests and other health data to measure biomarkers associated with ageing of the whole body (systemic) and of specific organs.

By comparing the level of each biomarker to the amount expected for their age, the team estimated whether someone appeared biologically ‘older’ or ‘younger’ than their chronological age.

Their results showed that, biologically speaking, younger generations may be ageing faster than previous generations. When they looked at systemic ageing markers, PROSPECT’s researchers found that people born between the mid-1960s and the mid-1970s had a 23% higher level of accelerated biological ageing than those born in the early 1950s. This meant that their bodies were acting a bit more like those of older people.

The team also found that people whose bodies were biologically older than their chronological age had a higher risk of developing cancer before they turned 55, particularly lung, gastrointestinal and uterine (womb or endometrial) cancer.

Outside of systemic ageing, the researchers also found links between ageing of specific parts of the body and certain cancers. For example, a biologically older immune system appeared to be linked with a higher risk of lung cancer. And they found a similar association between ‘older’ fat tissue with an increased risk of bowel 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,” says Dr David Scott, Director of Cancer Grand Challenges. 

A whole body approach

Although the team’s results don’t prove that faster biological ageing directly causes cancer, they highlight a shift in the way researchers are thinking about prevention. Instead of viewing cancer as a disease that begins in a single organ or cell, scientists are recognising it as a whole-body process, where many different things can play a part.

“In addition to identifying individual risk factors, we want to understand and potentially decode how environmental and lifestyle exposures become biologically embedded over time and ultimately drive cancer risk,” Cao explains.

There’s more research to do, but the team’s work serves as a proof of concept for how biological imprints, such as ageing markers, could be used to help identify someone’s cancer risk.

“Ultimately, we hope to shift cancer prevention earlier in life by identifying high-risk individuals sooner and uncovering new strategies to delay – or even prevent – the development of cancer.”

To learn more about early-onset cancer and why it’s rising, listen to our podcast episode: