Early-onset cancer explained: which cancers are rising in adults under 50, and what is known about why

A new analysis of national cancer records, published on October 6, 2026, by the World Cancer Research Fund (WCRF), reports that several cancers are being diagnosed more often in adults under 50. In England, the charity found, bowel cancer cases rose from 3.9 per 100,000 adults under 50 to 8.4 per 100,000 between 2001 and 2023. It reported increases for prostate, kidney, womb, liver, pancreatic and breast cancers as well.

The figures add to a run of studies on what researchers call early-onset cancer. They also raise questions that the headline numbers do not answer: how large the risk is, whether it is confined to the young, and what lies behind it.

What early-onset cancer means and how common it is

The term has no single official definition. A review in Nature Reviews Clinical Oncology describes early-onset cancers as those diagnosed in adults under 50 years of age, and most studies use that line.

Cancer at those ages is uncommon. The WCRF itself stressed that most cancers are still diagnosed in older adults. For colorectal cancer, the medical name for bowel cancer, the US Preventive Services Task Force (USPSTF) notes that the disease is most frequently diagnosed among persons aged 65 to 74 years. It is estimated that 10.5% of new colorectal cancer cases occur in persons younger than 50 years.

The English figures show the scale. A rate of 8.4 per 100,000 means that in a year, about one adult under 50 in every 12,000 was diagnosed with bowel cancer. The rate has doubled, and it has doubled from a low base.

Which cancers are rising in adults under 50

The WCRF compared diagnoses in England in 2001 and 2023, as reported by ITV News.

Cancer, adults under 50, England	2001	2023
Bowel, per 100,000 adults	3.9	8.4
Prostate, per 100,000 men	1	3.6
Womb, per 100,000 women	1.8	3.9
Breast, per 100,000 women	42	47.5
Kidney, number of cases	510	1,065

The charity found that prostate cancer had risen from one case per 100,000 men under 50 in 2001 to 3.6 cases in 2023. Some 510 adults under 50 were diagnosed with kidney cancer in 2001 compared to 1,065 in 2023. Breast cancer, by far the most common cancer in younger women, rose more slowly, from 42 to 47.5 per 100,000.

Studies from other countries point the same way. In the United States, researchers at the National Cancer Institute examined 2010 to 2019 and reported that fourteen cancers had incidence rates that increased in at least one early-onset age group. Incidence rate is the number of new cases in a year relative to the size of the population. They translated the trend into people: the largest excess in 2019 compared with expected diagnoses based on 2010 rates was in female breast cancer, with 4,834 additional cases, followed by colorectal cancer with 2,099, kidney cancer with 1,793 and uterine (womb) cancer with 1,209.

Worldwide, an analysis of the Global Burden of Disease database produced a figure that has been widely repeated: global incidence of early-onset cancer increased by 79.1% and the number of early-onset cancer deaths increased by 27.7% between 1990 and 2019. Despite the word incidence, that figure is a count of cases, so it also reflects three decades of population growth.

Not every cancer is rising, as the international comparison in the next section shows.

Whether the rise is confined to younger adults

The widest test of that question came in October 2025 from a team led by Amy Berrington de Gonzalez at the Institute of Cancer Research in London, working with the US National Cancer Institute. Their aim was to compare international cancer incidence trends in younger adults (aged 20 to 49 years) and older adults, using the World Health Organization cancer agency’s database.

They took 13 cancer types that earlier reports had flagged as rising in the young and measured the average annual percentage change (AAPC) in each country. Incidence rose in younger adults in most countries between 2003 and 2017 for 6 of the 13 cancer types.

Cancer type	Median yearly change, ages 20 to 49	Median yearly change, ages 50 and over
Thyroid	+3.57%	+3%
Kidney	+2.21%	+1.65%
Endometrial (womb lining)	+1.66%	+1.20%
Colorectal	+1.45%	+0.37%
Breast	+0.89%	+0.86%
Leukemia	+0.78%	+0.61%

The right-hand column is the point of the study. With one exception, incidence rates for these cancer types also increased in older adults in most countries. For thyroid, kidney, womb and breast cancers and leukemia, the trend in people under 50 looked much like the trend in people over 50.

Meanwhile some cancers were falling. For liver, oral, esophageal, and stomach cancer, rates decreased in younger adults in more than half the countries. Liver cancer is on the list of cancers the English analysis found rising, a reminder that national patterns differ.

The authors’ conclusion was measured. Cancer incidence had risen for several types in many countries, they wrote, but other than colorectal cancer, these increases occurred in both younger and older adults.

The American study reached a similar position. Of its fourteen rising cancers, nine also increased in at least one older-onset age group. And for most cancers there were not concomitant increases in mortality rates, meaning more diagnoses had not been matched by more deaths.

Why bowel cancer stands apart in younger adults

Colorectal cancer, which covers cancers of the colon and rectum and is called bowel cancer in Britain, breaks the pattern. In the international comparison it was the exception, since it only increased in older adults in about half the countries. The AAPC was greater in younger than older adults in 69% of countries.

A separate analysis of 50 countries and territories, led by the American Cancer Society, filled in the detail. Over the most recent decade studied, incidence rates of early-onset colorectal cancer were stable in 23 countries, but increased in 27 countries. The steepest rises were in New Zealand, Chile, Puerto Rico and England, at between 3.6% and 4% a year. In half of the rising countries the disease was flat or falling among older people: 14 of the 27 countries and territories showed either stable or decreasing trends in older adults.

The authors attribute falling or flat rates in older adults to changes in risk factors such as smoking and to the widespread use of screening. Against that backdrop the rise in younger adults stands out.

Deaths have moved too. In the United States, colorectal, uterine, and testicular cancer mortality rates increased in early-onset age groups, the National Cancer Institute team reported.

The pattern follows year of birth. Researchers call this a birth cohort effect: whatever raises the risk appears to act on people born after a certain date and to stay with them as they age. Studies in North America, Oceania and parts of Europe consistently attribute the rising early-onset colorectal cancer burden to a birth cohort effect, the 50-country paper notes.

A US registry study of people born from 1920 to 1990 found the same signature in other cancers. It concluded that 17 of 34 cancers had an increasing incidence in younger birth cohorts. For cancers of the small intestine, kidney and pancreas, the incidence rate was approximately two-to-three times higher in the 1990 birth cohort than in the 1955 birth cohort.

What might be causing early-onset cancer

A birth cohort effect narrows the search without ending it. The US registry authors write that trends in cancer incidence in recent birth cohorts largely reflect changes in exposures during early life. The question is which exposures.

Candidates are easy to list. Obesity has risen in children and young adults over the same decades, and the 50-country study lists it with diet and physical inactivity among the major risk factors for colorectal cancer. Changes in the wider environment and in gut bacteria have also been proposed.

Evidence tying any of them to the trend is thin. The authors of the 50-country study acknowledge that evidence that links birth cohort trends in specific risk factors to the rise in early-onset colorectal cancer is scarce. The Nature Reviews Clinical Oncology review, led from Harvard, reached the same verdict across cancer types: the effects of individual exposures remain largely unknown.

Detection is part of the story. More scans and more testing find more tumors, some of which would never have caused harm. The Harvard reviewers accept that wider screening has contributed to a certain extent, while arguing that a genuine increase in the incidence of early-onset forms of several cancer types also seems to have emerged. The US team put both explanations side by side, writing that the drivers could include a combination of established and perhaps new etiologic factors, and increased detection. Etiologic means causal.

Thyroid cancer was the fastest riser in the international study in young and old alike, a pattern consistent with wider testing.

The WCRF did not claim to have the answer either. “We need to understand what is driving these trends, including modifiable risk factors and exposures experienced earlier in life, changes in screening and diagnosis,” said Vanessa Gordon-Dseagu, a research manager at the charity.

What has changed in screening for early-onset cancer

Screening policy has already shifted for bowel cancer. In 2021 the USPSTF lowered its recommended starting age from 50 to 45. Its statement concludes with moderate certainty that screening for colorectal cancer in adults aged 45 to 49 years has moderate net benefit. The recommendation applies to adults with no symptoms and average risk.

Research is also being organized around the question. A British study known as Prospect-UK will track 250,000 people over time, looking at diet and lifestyle factors, ITV reported.

“While cancer is still much more common in older adults, these changing patterns among younger generations need to be treated as a serious research and cancer prevention priority,” said Giota Mitrou, the WCRF’s executive director of research and policy.

Screening ages differ between countries, and for an individual the right time to be tested depends on family history and symptoms, which is assessed by their doctor.

Gaps in the early-onset cancer evidence

The WCRF analysis, as reported, is a charity’s reading of registry data. Its English comparison rests on two years, 2001 and 2023, and it does not separate real increases from earlier diagnosis.

The international study has a limit its authors state themselves. Most countries with available data were high-middle-income countries, and the results might not be generalizable. Its data end in 2017.

The global 79.1% figure depends on modeled estimates. Its authors caution that the accuracy of the underlying data was compromised by the quality of cancer registry data in different countries.

All of these studies count diagnoses. None follows individuals, so none can show that a given exposure caused a given person’s cancer, and none can say how much of a rising rate is disease that would otherwise have been found later or not at all.

Several cancers are being diagnosed more often before 50, mostly in step with older adults and from low starting rates, and the one clear exception, bowel cancer, still lacks an explanation that has been tested.