Researchers called this year for an urgent need to understand the rising rates of cancer in people under the age of 50, saying we must finally get to grips with this growing problem.
Over the past few decades, the number of diagnoses for those early-onset cases – so-called because most tumours are diagnosed in people over 50 – has been rising in multiple cancer types, including those of the breast and prostate.
This trend has been most marked for cases of bowel cancer, with about a 50 per cent rise in the rate of people aged 25 to 49 being diagnosed with the condition since the 1990s in the US, Canada, Australia and many European countries.
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The explanation doesn’t seem to be wider screening, as this is mostly offered to people older than 50. Instead, proposed causes include changes to diet, sleep patterns, antibiotic use, stress, exercise levels, environmental contaminants or the microbiome.
Now, there is an increased focus on the problem, since an announcement in March by the and (CRUK) that understanding early-onset cancer is one of their nine new “grand challenges”.
The cause is probably some aspect of affluent modern life, says at Harvard Medical School. That is because the rate of early-onset cancers is rising progressively for people born in the 1950s, 1960s, 1970s and so on. “The evidence suggests each birth cohort has a higher risk at a given age,” says Ogino.
This coincides with a rise in wealth after the second world war. “In the 1940s, only a limited number of people had a wealthy lifestyle, with a car and eating as much as they want. Later on, more and more people had access to that lifestyle.”
The NCI and CRUK have asked for scientists to submit grant applications for research that investigates trends in the “exposome” – everything people are exposed to in the environment, such as contaminants and their lifestyle, that could influence their risk of developing medical conditions. They will announce who has been successful in March 2024.
Despite the trend of rising cancer diagnoses in younger people, most cases are still diagnosed in those aged 50 or older, so the shift hasn’t yet had much effect on total cancer incidence. Nevertheless, it shows no signs of stopping. “This is a big challenge,” says Ogino.
