While colorectal cancer is rising particularly fast among young adults, researchers have found that several other cancers have showed an increase in numerous countries over the past two decades – among adults of all ages – which they suggest could be obesity-linked, reports Medpage Today.
The global surveillance study found that between 2003 and 2017, incidence rates for six of 13 cancers assessed rose among younger adults (ages 20-49) in more than 75% of the countries studied, according to Amy Berrington de Gonzalez, DPhil, of the Institute of Cancer in England, and colleagues, whose study was published in Annals of Internal Medicine.
The sharpest uptick was for thyroid cancer, with a median average annual percentage change (AAPC) of 3.57%, followed by kidney cancer (AAPC 2.21%), endometrial cancer (AAPC 1.66%), colorectal cancer (AAPC 1.45%), breast cancer (AAPC 0.89%) and leukaemia (AAPC 0.78%).
Except for colorectal cancer, incidence rates of these cancers also increased among adults aged 50 and older in most countries, too: thyroid cancer (AAPC 3%), kidney cancer (AAPC 1.65%), endometrial cancer (1.20%), breast cancer (0.86%), and leukaemia (0.61%).
There was a modest increase in colorectal cancer rates (AAPC 0.37%) in about half of the 42 countries assessed.
In an accompanying editorial, Christopher Cann, MD, of Fox Chase Cancer Centre, and Efrat Dotan, MD, of the University of Pennsylvania Health System, noted that “over the past several decades, there has been an insidious increase in the incidence of cancer in young adults”.
“But the current findings indicate an increase in cancer burden across the adult age spectrum,” they said.
With this trend of increasing cancer incidence across all ages, the projected global financial impact “is considerable” at more than $25trn over the next 30 years, Cann and Dotan pointed out.
“The growing cost, coupled with an anticipated smaller supply of oncology providers, will place a significant strain on oncology care access.
“This compels us to consider the additional needs of these two groups of patients,” they added. “Although older adults may require more supportive measures during their treatments, younger adults experience detriments to their financial health and family development. These effects are more challenging to measure but augment the impact of the observed trends.”
Understanding the driving factors behind the rise in cancer rates should be the focus of future study, said Cann and Dotan, since it was beyond the scope of the current analysis.
Rising global obesity rates may be one of these drivers, Berrington de Gonzalez and co-authors suggested.
“The cancer types that we identified as increasing in younger and older adults in the majority of countries were all related to obesity and included some of those most strongly related to obesity, such as endometrial and kidney cancer, although some other obesity-related cancer types, like stomach and oesophageal cancer, decreased in younger adults in more than half of the countries.
“Another exception was breast cancer, for which obesity is associated with lower risk in premenopausal women,” the researchers noted.
“Formal analysis of obesity or other risk factors in these increasing cancer rates is warranted and requires long-term national survey data,” they wrote.
For the international comparative analysis, the researchers pulled data from the IARC GLOBOCAN Cancer Over Time database.
They included all countries with cancer incidence data for the 15-year period from 2003-2017, which included 42 countries in Asia (n =11), Europe (n=22), Africa (n=1), North and South America (n=6), and Australasia (n=2).
The most recent data for the majority of countries were from 2017, they said.
Data on 13 cancer types were assessed: leukaemia and breast, endometrial, colorectal, oral, kidney, liver, pancreatic, gallbladder, prostate, stomach, oesophageal, and thyroid cancer.
Very few countries had “noteworthy” differences in cancer trends between younger and older adults. Colorectal cancer was the one exception to this, with greater increasing trends in younger adults than older adults in 69% of countries: this difference was statistically significant in 38% of countries.
The increase in colorectal cancer incidence among young people “raises the possibility that there may be age-specific considerations that could be addressed to reverse this trend”, the editorialists wrote.
“It has been postulated that the summative exposure to environmental carcinogens early in life and microbiome alterations may lead to early-onset carcinogenesis.”
In young adults, there were decreases in liver (AAPC -0.14%), oral (AAPC -0.42%), oesophageal (AAPC -0.92%), and stomach cancer (AAPC -1.62%) rates in more than half of countries.
Rates of stomach (AAPC -2.05%) and oesophageal cancer (AAPC -0.25%) also decreased among older adults in more than half of the countries, but rates of liver (AAPC 2.17%) and oral cancer (AAPC 0.49%) increased.
Cancer incidence was also “broadly similar” between men and women, the researchers added. “For example, thyroid, colorectal, and kidney cancer increased in younger adults in most countries and at a faster rate than in older adults in both women and men.”
A lack of data after 2017 and the inclusion of mostly high-income countries were some study limitations.
Study details
Trends in cancer incidence in younger and older adults
Amy Berrington de Gonzalez, Martina Brayley, Reuben Frost et al.
Published in Annals of Internal Medicine on 21 October 2025
Abstract
Background
There is concern about widespread increases in cancer incidence rates in younger adults.
Objective
To compare international cancer incidence trends in younger adults (aged 20 to 49 years) and older adults (aged ≥50 years).
Design
Surveillance study.
Setting
Forty-two countries in Asia (n = 11), Europe (n = 22), Africa (n = 1), North and South America (n = 6), and Australasia (n = 2) with annual cancer incidence data from 2003 to 2017 in the International Agency for Research on Cancer’s GLOBOCAN database.
Participants
Adults aged 20 or older.
Measurements
Joinpoint regression to estimate the average annual percentage change (AAPC) in cancer incidence rates for 13 cancer types previously reported to be increasing in multiple countries in younger adults (leukaemia and breast, endometrial, colorectal, oral, kidney, liver, pancreatic, gallbladder, prostate, stomach, oesophageal, and thyroid cancer).
Results
Incidence rates increased in younger adults in most (>75%) countries between 2003 and 2017 for 6 of the 13 cancer types: thyroid cancer (median AAPC, 3.57%), breast cancer (median AAPC, 0.89%), colorectal cancer (median AAPC, 1.45%), kidney cancer (median AAPC, 2.21%), endometrial cancer (median AAPC, 1.66%), and leukaemia (median AAPC, 0.78%). Incidence rates for these cancer types also increased in older adults in most countries (median AAPCs, 3% for thyroid cancer, 0.86% for breast cancer, 1.65% for kidney cancer, 1.20% for endometrial cancer, and 0.61% for leukaemia). The exception was colorectal cancer, which only increased in older adults in about half the countries (median AAPC, 0.37%), and the AAPC was greater in younger than older adults in 69% of countries. For liver, oral, oesophageal, and stomach cancer, rates decreased in younger adults in more than half the countries.
Limitation
Most countries with available data were high-middle-income countries, and the results might not be generalisable.
Conclusion
Cancer incidence rates increased for several cancer types in many of the countries studied; however, other than colorectal cancer, these increases occurred in both younger and older adults. These findings can help inform future research and clinical and public health guidelines.
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