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Some countries have lowered the recommended age for mammograms in response to rising rates of early-onset breast cancer.Credit: Operation 2022/Alamy

The question of what age cancer screening should start is getting louder, as increasing numbers of people under 50 are being diagnosed, often well before they are eligible for routine testing.

“There is clearly something going on,” says Yoanna Pumpalova, a medical oncologist who treats colorectal cancer at the Columbia University Irving Medical Center in New York. “I see it every day. I have way too many patients who are my age — I’m 37 — or even younger, and it’s horrible. It’s more than it was five years ago; there’s no question about it.”

In addition to colorectal cancer, there also seems to be an uptick in other types of malignancies, including those affecting the breasts, stomach, kidney and pancreas (see ‘Starting early’). A BMJ Oncology study1 published in 2023 estimated that the global incidence of cancer in people under 50 will increase by more than 30% between 2019 and 2030, the authors citing diet, alcohol consumption and tobacco use as potential risk factors.

Some countries have responded by lowering the screening age for certain cancers. In 2024, Australia lowered the recommended starting age for colorectal cancer screening from 50 to 45, and as of late last year, every province and territory in Canada, except Quebec, had lowered its minimum age for routine breast-cancer screening from 50 to 40 or 45. This year, South Korea launched its new national cancer control plan, which states that from 2028, anyone aged 45 will be eligible for a national colonoscopy screening.

In the United States, recommendations for lowering the screening age are also gaining traction. In 2024, the US Preventive Services Task Force (USPSTF) — an independent panel of medical experts — lowered its recommended starting age for routine mammograms from 50 to 402. The group cited data from the US National Cancer Institute that showed that breast cancer rates among women in their 40s had risen by an average of 2% per year between 2015 and 2019.

The decision to lower the age for routine screening programmes requires a complex assessment of risks, benefits and individual circumstances. The challenge, says Robert Smith, a cancer epidemiologist at the American Cancer Society, a non-profit cancer advocacy and research organization headquartered in Atlanta, Georgia, is weighing the potential gain in lives saved versus the potential harms. Not only is it “very expensive”, Smith says, but broadening eligibility would expose more people to the risks of physical injury and false-positive results. “There really does need to be a certain prevalence of cancer in the population to justify inviting asymptomatic individuals to undergo screening,” he says.

A delicate balance

It’s not clear why some cancers are becoming more prevalent in people under 50. Mark Ebell, a primary care epidemiologist at Michigan State University in East Lansing, suspects that a combination of improved screening technologies and expanded screening programmes is a major factor. “Detection of more cancers in younger persons may just be a consequence of more sensitive and widely used imaging rather than a real increase in incidence.”

Other researchers, including the authors of the BMJ Oncology study, argue that routine screening for under-50s remains too limited to fully explain the trend. Data from the Australian Institute of Health and Welfare show that in 2025, around 7.2% of colorectal cancers in the country were diagnosed in people aged under 40 — a group that would not have been routinely screened — up from 2.2% in 2000.

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Early-onset cancer fuels calls for wider screening — but at what cost?