Summary
Background
Previous studies have shown that colorectal cancer incidence is increasing among younger adults (aged <50 years) in multiple high-income western countries in contrast with stabilising or decreasing trends in incidence in older adults (aged ≥50 years). This study aimed to investigate contemporary colorectal cancer incidence trends in younger adults versus older adults.
Methods
Colorectal cancer incidence data, including year of diagnosis, sex, and 5-year age group for 50 countries and territories, were extracted from the WHO–International Agency for Research on Cancer Cancer Incidence in Five Continents Plus database. The Human Development Index 2022 was retrieved from the United Nations Development Programme and grouped into very high (>0·80), high (0·70–0·79), medium (0·55–0·69), and low (<0·55) categories. Age-standardised incidence rates (ASR) per 100 000 person-years of early-onset (diagnosed between ages 25 to 49 years) and late-onset (diagnosed between ages 50 to 74 years) colorectal cancer (ICD 10th revision, C18–20), diagnosed between 1943–2003 and 2015–17, were calculated using the direct method and Segi–Doll world standard population). The primary study objective was to examine contemporary colorectal cancer incidence trends in younger adults versus older adults using data until 2017 from 50 countries and territories. Temporal trends were visualised and quantified with joinpoint regression, stratified by age at diagnosis (25–49 years or 50–74 years). Average annual percentage changes (AAPC) were estimated.
Findings
In the most recent 5 years (2013–17 for all countries analysed, except for Japan [2011–15], Spain [2012–16], and Costa Rica [2012–16]), the incidence rate of early-onset colorectal cancer was highest in Australia (ASR 16·5 [95% CI 16·1–16·9]), the USA (Puerto Rico; 15·2 [14·2–16·2]), New Zealand (14·8 [14·0–15·6]), the USA (14·8 [14·7–14·9]), and South Korea (14·3 [14·0–14·5]) and lowest in Uganda (4·4 [3·6–5·2]) and India (3·5 [3·3–3·7]). The highest incidence rates among older adults were found in the Netherlands (168·4 [166·9–170·0]) and Denmark (158·3 [155·8–160·9]) and the lowest were in Uganda (45·9 [38·5–51·4]) and India (23·5 [22·8–24·3]). In terms of AAPC, in the most recent 10 years, incidence rates of early-onset colorectal cancer were stable in 23 countries, but increased in 27 countries with the greatest annual increases in New Zealand (AAPC 3·97% [95% CI 2·44–5·52]), Chile (3·96% [1·26–6·74]), Puerto Rico (3·81% [2·68–4·96]), and England (3·59% [3·12–4·06]). 14 of the 27 countries and territories showed either stable (Argentina, France, Ireland, Norway, and Puerto Rico) or decreasing (Australia, Canada, Germany, Israel, New Zealand, Slovenia, England, Scotland, and the USA) trends in older adults. For the 13 countries with increasing trends in both age groups, the average annual percentage increase in younger compared to older adults was higher in Chile, Japan, Sweden, the Netherlands, Croatia, and Finland; lower in Thailand, France (Martinique), Denmark, and Costa Rica; and similar in Türkiye, Ecuador, and Belarus. The rise in early-onset colorectal cancer was faster among men than women in Chile, Puerto Rico, Argentina, Ecuador, Thailand, Sweden, Israel, and Croatia, whereas faster increase among women compared to men was in England, Norway, Australia, Türkiye, Costa Rica, and Scotland.
Interpretation
Early-onset colorectal cancer incidence rates are rising in 27 of 50 countries and territories examined, with the rise either exclusive to early-onset disease or faster than the increase in older adults in 20 of the 27 countries. The findings underscore the need for intensified efforts to identify factors driving these trends and increase awareness to help facilitate early detection.
Funding
Intramural Research Program of the American Cancer Society, Cancer Grand Challenges, and National Institutes of Health.
Introduction
Colorectal cancer is the third most commonly diagnosed cancer and the second leading cause of cancer death, responsible for more than 1·9 million new cases and almost 904 000 deaths in 2022 worldwide.1 Previous studies have reported rising colorectal cancer incidence rates among younger adults (typically defined as diagnoses before age 50 years) in several high-income countries, including Australia, Canada, New Zealand, the UK, and the USA.2, 3, 4 This contrasts with decreasing or plateauing trends among older adults (over the age of 50 years), which is likely to be attributable to changes in multiple risk factors (eg, smoking cessation) and the widespread use of screening.5 The increase in early-onset colorectal cancer has also been reported in South Korea and Hong Kong, but paralleling the increase in older adults.2, 6 A prior study of the most comprehensive global analysis of early-onset colorectal cancer incidence examined 36 countries using data until 2012 for 30 countries and until 2015–17 for six countries.2 Studies using data from the Global Burden of Disease have examined trends in early-onset colorectal cancer incidence from 1990 to 2019, primarily focusing on regional and global estimates, based largely on secondary and modelled data;7 however, an absence of country-specific characterisation of the latest trends in incidence using high-quality population-based cancer registry data hinders our ability to inform cancer prevention policies tailored to the unique circumstances of each country. Using high-quality population-based cancer registry data, we comprehensively evaluate the trends in incidence rates of colorectal cancer in younger adults (aged 25–49 years) vs older adults (aged 50–74 years) in 50 countries and territories.
Research in context.
Evidence before this study
We searched PubMed for articles published in English from Jan 1, 2000, to June 30, 2024, using the search terms, “colorectal cancer”, “colon cancer”, “rectal cancer”, “incidence”, “early-onset”, “young-onset”, and “young adults”. Studies were considered if they examined colorectal cancer incidence or mortality trends. In several high-income countries, increases in early-onset colorectal cancer incidence since the mid-1990s have been reported in contrast with stabilising or decreasing trends among older adults. A 2019 study of the most comprehensive global analysis of colorectal cancer incidence examined 36 countries using data until 2010–12 (for 30 countries) or until 2015–17 (for six countries).
Added value of this study
Using high-quality population-based cancer registry data until 2017, this study presents contemporary trends in early-onset colorectal cancer incidence across 50 countries and territories, including 12 additional countries (Argentina, Bahrain, Belarus, Chile, Columbia, Ecuador, France [Martinique], Iceland, Kuwait, the USA [Puerto Rico], Qatar, and Uganda) since the last published report on colorectal cancer incidence trends. The findings show that the rising incidence of early-onset colorectal cancer is no longer limited to high-income countries; it now extends to countries and territories in Latin America and the Caribbean (Argentina, Chile, Costa Rica, Ecuador, Martinique, and Puerto Rico), Asia (Israel, Japan, Thailand, and Türkiye), and eastern Europe (Belarus).
Implications of all the available evidence
The trend of increasing colorectal cancer incidence among younger adults in several countries worldwide could lead to an increased global burden of the disease, affecting adults of all age groups. This finding highlights the urgent need to raise awareness among the general public, primary health-care providers, cancer control experts, and policy makers to aid early detection, identify the factors driving these trends (prioritising modifiable risk factors during early life), and develop preventive strategies tailored to the social and cultural values of young people in diverse global contexts.
Methods
Study design and data source
Colorectal cancer incidence data were extracted from the WHO–International Agency for Research on Cancer Cancer Incidence in Five Continents Plus database (CI5plus), a compendium series of high-quality population-based cancer registry data at the national or subnational level, available for 135 registries, and including year of diagnosis, sex (male, female), and 5-year age group.8 Data collected by hospitals and clinics are the predominant source for sex and race and ethnicity information for population-based cancer registries. Data with national coverage were available for 27 countries, while the remaining 23 relied on one or more subnational population-based cancer registries for the diagnoses years from 1943–2003 to 2015–17 (appendix pp 5–7). The geographical definition follows the UN regional classification (World Population Prospects 2024), except Cyprus, which, although part of western Asia, was classified as a European country. The Human Development Index 2022 was retrieved from the United Nations Development Programme9 and grouped into very high (>0·80), high (0·70–0·79), medium (0·55–0·69), and low (<0·55) categories. This study used de-identified publicly available data, which is considered non-human participants research under the Common Rule (US federal regulation 45 CFR part 46); thus, institutional review board approval and informed consent were not needed.
Outcomes
Outcomes were incidence of early-onset and late-onset colorectal cancer (ICD 10th revision, C18–20), defined as diagnoses between ages 25–49 years and 50–74 years, respectively. The age categories were chosen to improve comparability across countries with varying population sizes and life expectancies (appendix pp 5–7).
Statistical analysis
Temporal trends stratified by age at diagnosis (25–49 years or 50-74 years) were quantified using National Cancer Institute's Joinpoint program (version 5.2.0), fitting a series of joined straight lines on a logarithmic scale to the annual age-standardised incidence rates per 100 000 person-years (appendix pp 2–4). The direct method and the Segi–Doll world standard population10, 11 were used to calculate the age-standardised incidence rates. Annual percentage changes (APCs) for each straight line were estimated, and weighted averages of the APCs (AAPCs) were calculated for the most recent 5-year and 10-year periods, and the entire diagnosis period, with weights corresponding to the length of each APC. The difference in AAPCs between groups was tested using Z-test. Two-sided p values of less than 0·05 were considered statistically significant. R (version 4.4.1) or Origin (version 2024b) was used for data visualisation.
Role of the funding source
The funders of the study had no role in the study design, data collection, data analysis, data interpretation, or writing of the report.
Results
The table presents population coverage of 135 cancer registries, diagnosis years, and Human Development Index of the 50 countries and territories (27 from Europe, 11 from Asia, seven from Latin America and the Caribbean, two from North America, two from Oceania, and one from Africa). In 23 countries with subnational population-based cancer registries, coverage ranges from 0·6% in China to 74·5% in Canada. In the most recent 5 years, the highest incidence rates of early-onset colorectal cancer were observed in Australia (ASR 16·5 [95% CI 16·1–16·9]), the USA (Puerto Rico; 15·2 [14·2–16·2]), New Zealand (14·8 [14·0–15·6]), the USA (14·8 [14·7–14·9]), and South Korea (14·3 [14·0–14·5]), whereas the highest incidence rates among older adults were found in the Netherlands (168·4 [166·9–170·0]), Denmark (158·3 [155·8–160·9]), Japan (156·0 [154·2–157·8]), Spain (148·2 [146·0–150·4]), and Croatia (146·8 [143·9–149·7]). The lowest incidence rates were observed in India, Uganda, Costa Rica, and Ecuador in both age groups.
Table.
Characteristics of 50 countries and territories and their colorectal cancer (C18–C20) incidence rates by age group for the most recent 5 years*
| HDI in 2022† | Population coverage in CI5plus (%) | Diagnosis years available in CI5plus |
Number of cases and ASR for the most recent 5 years* |
||||||
|---|---|---|---|---|---|---|---|---|---|
| Age at diagnosis, 25–49 years |
Age at diagnosis, 50–74 years |
||||||||
| Cases | ASR per 100 000 person-years (95% CI) | Rank | Cases | ASR per 100 000 person-years (95% CI) | Rank | ||||
| Africa | |||||||||
| Uganda | 0·55 | Subnational (7·1%) | 1993–2017 | 138 | 4·4 (3·6–5·2) | 49 | 210 | 44·9 (38·5–51·4) | 49 |
| Asia | |||||||||
| South Korea | 0·93 | National | 1999–2017 | 15 806 | 14·3 (14·0–14·5) | 5 | 87 630 | 121·4 (120·6–122·2) | 11 |
| Japan | 0·92 | Subnational (8·8%) | 1978–2015 | 2825 | 13·5 (13·0–14·0) | 6 | 32 769 | 156·0 (154·2–157·8) | 3 |
| Israel | 0·92 | National | 1963–2017 | 1465 | 11·2 (10·6–11·8) | 20 | 8559 | 99·6 (97·4–101·7) | 28 |
| Qatar | 0·88 | Subnational (11·1%) | 2003–17 | 39 | 10·1 (6·9–13·3) | 27 | 115 | 82·4 (66·9–97·9) | 39 |
| China | 0·79 | Subnational (0·6%) | 2002–17 | 1494 | 9·5 (9·0–10·0) | 31 | 17 079 | 99·2 (97·6–100·7) | 29 |
| Kuwait | 0·85 | Subnational (32·8%) | 1998–2017 | 160 | 8·9 (7·6–10·3) | 35 | 456 | 67·3 (61·0–73·5) | 42 |
| Türkiye | 0·86 | Subnational (8·1%) | 1998–2017 | 1111 | 8·6 (8·1–9·1) | 38 | 5144 | 74·0 (72·0–76·1) | 41 |
| Philippines | 0·71 | Subnational (6·3%) | 1983–2017 | 932 | 8·3 (7·8–8·9) | 39 | 3102 | 77·5 (74·7–80·3) | 40 |
| Bahrain | 0·89 | Subnational (46·5%) | 1998–2017 | 82 | 8·2 (6·4–10·0) | 40 | 290 | 66·7 (58·8–74·6) | 43 |
| Thailand | 0·80 | Subnational (7·7%) | 1993–2017 | 812 | 7·6 (7·1–8·1) | 42 | 3930 | 54·9 (53·2–56·7) | 47 |
| India | 0·64 | Subnational (1·5%) | 2003–17 | 1405 | 3·5 (3·3–3·7) | 50 | 4035 | 23·5 (22·8–24·3) | 50 |
| Europe | |||||||||
| Norway | 0·97 | National | 1953–2017 | 1265 | 13·3 (12·6–14·0) | 8 | 11 207 | 145·0 (142·3–147·7) | 6 |
| Netherlands | 0·95 | National | 1989–2017 | 3779 | 12·1 (11·7–12·5) | 9 | 47 117 | 168·4 (166·9–170·0) | 1 |
| Iceland | 0·96 | National | 1955–2017 | 68 | 12·0 (9·1–14·8) | 10 | 455 | 103·3 (93·8–112·8) | 25 |
| Croatia | 0·88 | National | 1988–2017 | 897 | 11·9 (11·1–12·7) | 12 | 10 327 | 146·8 (143·9–149·7) | 5 |
| Germany | 0·95 | Subnational (7·8%) | 2003–17 | 1417 | 11·9 (11·2–12·5) | 13 | 12 271 | 114·0 (112·0–116·1) | 19 |
| Ireland | 0·95 | National | 1994–2017 | 1048 | 11·8 (11·0–12·5) | 14 | 7318 | 123·8 (120·9–126·6) | 9 |
| UK, Northern Ireland | 0·94 | National | 1993–2017 | 378 | 11·4 (10·3–12·6) | 16 | 3140 | 119·2 (115·0–123·4) | 13 |
| UK, England | 0·94 | National | 1971–2017 | 11 090 | 11·4 (11·2–11·6) | 17 | 89 402 | 109·0 (108·3–109·7) | 21 |
| UK, Wales | 0·94 | National | 2003–17 | 585 | 11·3 (10·4–12·2) | 18 | 6199 | 119·4 (116·3–122·4) | 12 |
| UK, Scotland | 0·94 | National | 1978–2017 | 1081 | 11·2 (10·5–11·9) | 19 | 10 105 | 116·4 (114·1–118·6) | 17 |
| France | 0·91 | Subnational (11·8%) | 1998–2017 | 1372 | 10·7 (10·1–11·3) | 22 | 13 299 | 114·6 (112·6–116·5) | 18 |
| Switzerland | 0·97 | Subnational (26·2%) | 1998–2017 | 440 | 10·4 (9·4–11·4) | 23 | 3349 | 100·9 (97·5–104·4) | 27 |
| Denmark | 0·95 | National | 1943–2017 | 1052 | 10·4 (9·7–11·0) | 24 | 15 349 | 158·3 (155·8–160·9) | 2 |
| Czechia | 0·90 | National | 1983–2017 | 2077 | 10·2 (9·8–10·7) | 25 | 24 963 | 138·4 (136·7–140·2) | 7 |
| Spain | 0·91 | Subnational (18·2%) | 1993–2016 | 1820 | 10·1 (9·6–10·6) | 26 | 17 901 | 148·2 (146·0–150·4) | 4 |
| Slovenia | 0·93 | National | 1983–2017 | 396 | 9·9 (9·0–10·9) | 28 | 3992 | 117·5 (113·9–121·2) | 14 |
| Malta | 0·92 | National | 1993–2017 | 73 | 9·7 (7·5–12·0) | 29 | 812 | 106·9 (99·5–114·4) | 23 |
| Sweden | 0·95 | National | 1960–2017 | 1649 | 9·7 (9·2–10·1) | 30 | 16 548 | 101·4 (99·8–103·01) | 26 |
| Austria | 0·93 | National | 1998–2017 | 1565 | 9·3 (8·8–9·8) | 32 | 12 278 | 89·4 (87·8–91·0) | 35 |
| Finland | 0·94 | National | 1953–2017 | 827 | 9·2 (8·6–9·9) | 33 | 8605 | 89·0 (87·1–91·0) | 36 |
| Estonia | 0·90 | National | 1983–2017 | 216 | 9·2 (8·0–10·4) | 34 | 2392 | 113·8 (109·1–118·4) | 20 |
| Belarus | 0·80 | National | 1983–2017 | 1561 | 8·9 (8·4–9·3) | 36 | 15 674 | 117·1 (115·2–118·9) | 15 |
| Italy | 0·91 | Subnational (4·5%) | 2003–17 | 466 | 8·8 (8·0–9·6) | 37 | 4701 | 108·8 (105·6–112·0) | 22 |
| Cyprus | 0·91 | Subnational (71·5%) | 1998–2017 | 141 | 8·2 (6·7–9·6) | 41 | 1061 | 87·2 (81·9–92·5) | 37 |
| Poland | 0·88 | Subnational (3·2%) | 1999–2017 | 157 | 7·2 (6·0–8·3) | 44 | 1900 | 93·5 (89·3–97·8) | 33 |
| Lithuania | 0·88 | National | 1988–2017 | 374 | 7·1 (6·4–7·9) | 45 | 4380 | 94·9 (92·0–97·7) | 31 |
| Latvia | 0·88 | National | 1983–2017 | 228 | 6·4 (5·6–7·2) | 47 | 3101 | 95·0 (91·6–98·4) | 30 |
| Latin America and the Caribbean | |||||||||
| USA, Puerto Rico | Not applicable | National | 2003–17 | 884 | 15·2 (14·2–16·2) | 2 | 5732 | 106·0 (103·2–108·8) | 24 |
| France, Martinique | Not applicable | National | 1993–2017 | 85 | 11·9 (9·4–14·5) | 11 | 576 | 91·2 (83·7–98·7) | 34 |
| Argentina | 0·85 | Subnational (4·2%) | 2003–17 | 324 | 11·6 (10·3–12·9) | 15 | 1593 | 85·6 (81·4–89·8) | 38 |
| Chile | 0·86 | Subnational (2·2%) | 1998–2017 | 76 | 10·7 (8·3–13·1) | 21 | 296 | 62·2 (55·1–69·4) | 44 |
| Colombia | 0·76 | Subnational (9·1%) | 2003–17 | 604 | 7·5 (6·9–8·1) | 43 | 2455 | 57·7 (54·5–59·0) | 45 |
| Ecuador | 0·77 | Subnational (11·5%) | 1985–2017 | 216 | 6·6 (5·7–7·5) | 46 | 674 | 46·3 (42·8–49·8) | 48 |
| Costa Rica | 0·81 | National | 1982–2016 | 525 | 6·2 (5·6–6·7) | 48 | 2320 | 56·1 (53·8–58·4) | 46 |
| North America | |||||||||
| USA | 0·93 | Subnational (9·3%) | 1978–2017 | 77 540 | 14·8 (14·7–14·9) | 4 | 416 509 | 94·3 (94·0 −94·6) | 32 |
| Canada | 0·94 | Subnational (74·5%) | 1978–2017 | 6438 | 13·5 (13·1–13·8) | 7 | 47 008 | 117·1 (116·0–118·1) | 16 |
| Oceania | |||||||||
| Australia | 0·95 | National | 1993–2017 | 7022 | 16·5 (16·1–16·9) | 1 | 40 914 | 123·9 (122·7–125·1) | 8 |
| New Zealand | 0·94 | National | 1983–2017 | 1179 | 14·8 (14·0–15·6) | 3 | 7954 | 122·3 (119·6–125·0) | 10 |
ASR=age-standardised rate. HDI=Human Development Index. CI5plus=Cancer Incidence in Five Continents Plus database. Population coverage (%) refers to the extent to which the registry captures data on all diagnosed cancer cases within its target population.
The most recent five diagnosis years were 2013–17 for all countries analysed, except for Japan (2011–15), Spain (2012–16), and Costa Rica (2012–2016).
HDI has four categories—very high (>0·80), high (0·70–0·79), medium (0·55–0·69), and low (<0·55).
Figure 1 illustrates trends in colorectal cancer incidence rates by age group (appendix pp 8–11 for APCs, AAPCs, and corresponding 95% CIs). Increasing incidence rates among younger adults in contrast to decreasing or plateauing rates among older adults were primarily observed in North America, Oceania, and several European countries (eg, Slovenia, Germany, Sweden, and England). Notably, many countries in these regions experienced an increase in early-onset colorectal cancer incidence that began during 1994–97 (Canada, Denmark, Sweden, the Netherlands, and the USA), 2003–09 (Australia, France, New Zealand, Norway, and England), and in 2015 in Belarus, following stable or declining trends. In contrast, countries with rising early-onset colorectal cancer incidence rates in recent years in Latin America and the Caribbean and Asia more often showed a steady increase throughout the period except in Japan, where the increase began in 2009 by 4·7% per year, following two decades of stable trends. The increase in early-onset colorectal cancer incidence paralleled increasing trends in older adults, except in countries where the rate in older adults stabilised (Argentina and Puerto Rico) or decreased (Israel). Meanwhile, the South Korea has seen a decrease of 5–8% per year from the early 2010s in both age groups.
Figure 1.
Trends in colorectal cancer incidence rates in younger (25–49 years) and older adults (50–74 years)
*Subnational data. Population coverage is detailed in the table and details on population-based cancer registries are in the appendix (pp 5–7). Joinpoint (version 5.2.0) was used to fit a series of joined straight lines on a logarithmic scale of age-standardised incidence rates (dots) using the grid search method and the permutation test with the maximum number of joinpoints set at two (appendix pp 2–4). All annual percentage changes and corresponding 95% CIs in each segment can be found in the appendix (pp 8–11).
Figure 2 shows the AAPCs for the last 10 years. During the last decade, early-onset colorectal cancer incidence rates remained stable in 23 countries but increased in 27 countries with the fastest rises in New Zealand (AAPC 3·97% [95% CI 2·44–5·52]), Chile (3·96% [1·25–6·74]), Puerto Rico (3·81 [2·68–4·96]) and England (3·59% [3·12–4·06]). The increasing trend was confined to the younger adults in 14 countries, where the trend among older adults either decreased (Israel, Canada, the USA, England, Germany, Scotland, Slovenia, Australia, and New Zealand) or remained stable (Puerto Rico, Argentina, Norway, France, and Ireland). Trends over the last 5 years were generally consistent with those of the last 10 years (appendix pp 8–11). Notable exceptions were the stabilisation of increases among younger adults in Croatia and Germany (appendix pp 8–9) and the stabilisation of decreasing rates among older adults in the UK, Scotland, and the USA (appendix pp 10–11).
Figure 2.
The most recent 10-year average annual percentage change in age-standardised incidence rates in colorectal cancer in younger (25–49 years) and older (50–74 years) adults from 2008 to 2017*
AAPC=average annual percentage change. *Exceptions are Costa Rica and Spain (2005–16) and Japan (2006–15). †Subnational data. Population coverage is detailed in the table and details on population-based cancer registries are in the appendix (pp 5–7). Dots represent the 10-year AAPC, and lines indicate the corresponding 95% CIs (appendix pp 8–9). Sex-specific results are shown in the appendix (pp 14–15, 18–19).
In the 13 countries with increases in both age groups, the 10-year AAPC was larger in younger than in older adults in Chile, Japan, Sweden, the Netherlands, Croatia, and Finland; was similar in Belarus, Ecuador, and Türkiye; and was smaller in younger adults in Thailand, France (Martinique), Costa Rica, and Denmark (appendix pp 12–13).
Of the 27 countries and territories experiencing an increase in early-onset colorectal cancer incidence, differences in AAPCs between sexes were found in 14 countries (appendix pp 14–15, 18–19). There was a faster increase in incidence of early-onset colorectal cancer in men than in women in Chile, Puerto Rico, Argentina, Ecuador, Thailand, Sweden, Israel, and Croatia. Conversely, there was a faster increase in incidence of early-onset colorectal cancer in women than in men in England, Norway, Australia, Türkiye, Costa Rica, and Scotland.
Race and ethnicity data were available only for the USA, thus stratification by race and ethnicity was not pursued.
Discussion
Based on high-quality population-based cancer registry data, incidence rates of early-onset colorectal cancer have increased in 27 of 50 countries and territories in the last decade until 2017, with the steepest inclines in Chile, New Zealand, Norway, Puerto Rico, and England. The rise in colorectal cancer was confined to the younger age group (25–49 years) in 14, primarily high-income, western countries (Australia, Canada, France, Germany, Ireland, New Zealand, Norway, Slovenia, England, Scotland, and the USA), and also in Argentina, Israel, and Puerto Rico. In six additional countries, the increase in early-onset colorectal cancer outpaced that in older adults (Chile, Croatia, Finland, Japan, Sweden, and the Netherlands). Expanding upon previous research, our findings show that the rise in early-onset colorectal cancer is no longer confined to high-income western countries; it now extends to diverse economies and countries in eastern Europe, Asia, and Latin America and the Caribbean.
Australia, Canada, New Zealand, and the USA, were historically the highest-risk countries for colorectal cancer and among the first to report a rise in early-onset disease as opposed to the rapid declines observed in older adults.3 Our findings show that the rising incidence of early-onset colorectal cancer has continued at 2–4% annually until 2017. Largely consistent with previous analyses,2, 3 13 of the 27 European countries, with increasing early-onset colorectal cancer, have very high Human Development Index, and are located mostly in northern and western Europe. With 5 more years of data since previous publication on colorectal cancer incidence trends, the present analysis revealed upturns of previously stable trends in younger adults in Croatia, France, and Ireland.2 Additionally, the earlier declines of over 1% per year in early-onset colorectal cancer in Austria, Italy, and Lithuania until 20144, 12 have now stabilised, indicating a shift away from such favourable trends. The heterogeneous trends of plateauing or slower increases in older adults across Europe probably reflect differences in risk factor patterns, such as variations in smoking declines, and the uptake of colorectal cancer screening.13
Trend analyses by birth year in North America and Oceania and some high-income European nations consistently attribute the rising early-onset colorectal cancer burden to a birth cohort effect.3, 14 The generational shift in colorectal cancer risk, suggested by the birth cohort trend in cancer incidence, indicates an emergence of environmental and lifestyle exposures that affect early life and young adulthood in post-baby boomer generations (born after 1950). Children and adolescents in these highly industrialised and urbanised countries were probably among the earliest to uptake detrimental dietary exposures and sedentary lifestyles associated with economic wealth. Although evidence that links birth cohort trends in specific risk factors to the rise in early-onset colorectal cancer is scarce, analyses of nationally representative survey data in the USA have revealed increasing risks of obesity, type 2 diabetes, and metabolic syndrome among people born between 1965 and 1980 and the subsequent birth cohorts,15 aligning with birth cohort trends in colorectal cancer incidence.3, 14 Without interventions, the ageing of the generations born after 1950 could manifest as increased colorectal cancer incidence in older individuals, potentially impeding or reversing decades of progress made against the disease. In the USA, the impact of ageing in the high-risk generation is already apparent, as seen in the plateauing of the previously rapid 2% per year decline in colorectal cancer incidence in middle-aged (50–64 years) individuals since 2011.5
Our findings show that the increase in early-onset colorectal cancer is now observed not only in high-income western countries, but also in countries in Asia and Latin America and the Caribbean. Countries with the highest Human Development Index and high colorectal cancer incidence, in particular, have shown a similar diverging trend as the trends seen in Australia, Canada, New Zealand, and the USA. In Israel, the long-term parallel increases in both age groups diverged in 2005, when the rate in older adults began to plummet, probably a result of the delayed impact of the nationwide screening programme implemented in 1995.16 Similarly, the rapid rise in early-onset colorectal cancer contrasts with plateauing trends in older adults in Argentina and Puerto Rico, which might partly reflect screening activities implemented in the 1990s and 2013, respectively.17 The dramatic downturn of colorectal cancer incidence in both age groups in South Korea could be attributable to the nationwide colorectal cancer screening programme initiated in 2004 for individuals aged 50 years and older and the widespread adoption of opportunistic screening—48% of individuals in their 40s had been screened in a 2022 national survey—concurrently conducted with organised screenings for gastric cancer and breast cancer that commence at age 40 years.18
Distinct patterns also emerged in these regions with the rise in early-onset colorectal cancer frequently occurring alongside the increase in older adults. The simultaneous increases in colorectal cancer in both age groups might relate to the compressed economic growth and urbanisation within just a few decades. For example, Japan, having achieved notable economic advancement decades ahead of many of its regional counterparts, has seen the steepest rise in early-onset colorectal cancer in Asia. Similarly, Chile, which has sustained steady economic growth over last decades and outperformed neighbouring countries in several economic measures, has shown the fastest increase in early-onset colorectal cancer in Latin America and the Caribbean. Key determinants, however, remain elusive and are likely to differ, given the diverse social contexts and the extent to which economic growth influences major colorectal cancer risk factors, such as diets, physical inactivity, and obesity, across populations. Previous studies have noted that the rising incidence of colorectal cancer in several Latin American countries coincided with the economic liberalisation and globalisation of food systems in the late 1980s to early 1990s and subsequently with the pronounced obesity epidemic that affected all ages.19 For instance, from 1990–2022, the obesity prevalence among children (aged 5–19 years) increased from 6–7% to 22–33% in Chile and from 3% to 19–22% in Argentina, larger than the rise from 11–12% to 19–22% in the USA.20 Evidence from a US-based prospective cohort study of women suggested that each 5-unit increase in BMI measured at age 18 years was associated with a 20% increased risk of early-onset colorectal cancer.21 Meanwhile, a substantially lower prevalence of obesity in Japan and neighbouring east Asian countries suggests factors beyond bodyweight. A considerable shift from traditional diets, rich in low-fat and high-fibre foods, to increased consumption of red or processed meat, sugars, and ultra-processed convenience foods has probably contributed, at least in part. Between 1961 and 2021, South Korea and Japan saw a dramatic increase in meat intake, with a 19-times increase in South Korea and seven-times increase in Japan.22
Although germline mutations and family history of colorectal cancer are more frequent among individuals with early-onset colorectal cancer,23 most early-onset colorectal cancers are sporadic, for which underlying causes and causal pathways are largely unknown. Although most evidence to date is from high-income countries, studies examining exposure during adolescence or young adulthood have highlighted the importance of various established risk factors (including prolonged sitting, diet quality, sugar-sweetened beverage consumption, alcohol consumption, obesity, diabetes, and metabolic syndrome) in the carcinogenesis of early-onset colorectal cancer or its precursor (summarised in the appendix pp 16–17). Investigations into microbial exposures throughout the life course, including diets high in sulphur and birth via caesarean delivery, have yielded provocative findings, whereas evidence on antibiotic use is inconclusive. Efforts to establish the aetiology of early-onset colorectal cancer should continue, focusing on recent generations and prioritising modifiable risk factors.
The concurrent increases in colorectal cancer in both age groups in Asia and Latin America and the Caribbean might also partially reflect limited screening capacity or suboptimal uptake (eg, Japan),24 which could have altered the increase of colorectal cancer in older adults if adequate screening had been performed. Coupled with the stagnation in reducing colorectal cancer incidence among older adults, the simultaneous rise in colorectal cancer among younger adults and the inadequate access to appropriate treatment in many countries in these regions is likely to lead to an increase in colorectal cancer-related deaths, as projected in a previous study,25 underscoring the urgent need to increase awareness of the concerning trends across age groups.
To curb the rise in early-onset colorectal cancer, the American Cancer Society lowered the recommended starting age for colorectal cancer screening from 50 years to 45 years for average-risk individuals in 2018, and the US Preventive Services Task Force followed suit in 2021. As of July 1, 2024, the eligible age for the National Bowel Cancer Screening Program in Australia was lowered from 50 years to 45 years.26 Expanding average-risk screening to younger ages, however, remains controversial, even in high-resource settings, due to the low absolute incidence of early-onset colorectal cancer and concerns about diverting screening capacity from older adults or high-risk individuals who would benefit more at a lower cost.27 In countries adopting lowering screening ages, challenges remain in achieving optimal screening prevalence and ensuring equitable access to all eligible populations, as well as determining the effectiveness of screening based on empirical data. With the absence of screening tools, most early-onset colorectal cancers are diagnosed through symptoms often at an advanced stage and more frequently in the distal colon (right-sided) and rectum.28 Thus improving awareness among health-care providers and the public about the signs and symptoms of early-onset colorectal cancer (eg, rectal bleeding, abdominal pain, altered bowel habits, and unexplained weight loss) remains a primary opportunity for early detection.29 Additionally, prioritising the collection of family cancer history can be a key strategy for identifying individuals at higher risk for early-onset colorectal cancer, especially among siblings and relatives of those with early-onset colorectal cancer. A study estimated that half of early-onset colorectal cancer would be diagnosed earlier and up to 16% potentially prevented30 if colonoscopy was performed at the age recommended by family history-informed guidelines.23
Early-onset colorectal cancer strikes in the most active years of life, causing interruptions in education, work, and family building, as well as significant psychosocial challenges and long-term financial hardship. Despite international consensus guidelines recommending the same treatment across age groups,31 younger adults with colorectal cancer often receive more aggressive treatment (eg, postoperative systematic chemotherapy), but achieve only marginal gain in survival compared with their older counterparts,32 suggesting potentially long-lasting or late effects of treatment among survivors of early-onset colorectal cancer. Although some high-income countries have now established age-specific oncology care, expanding these initiatives to lower-income countries presents challenges, highlighting the need for international support to increase awareness and research aimed to addressing the unique needs of young patients with cancer and their families.
The findings of this study are strengthened by a systematic evaluation of the trends in early-onset colorectal cancer using up-to-date high-quality population-based cancer registry data. The assessment of contemporary trends in early-onset colorectal cancer across 50 countries and territories includes 12 countries (Puerto Rico, Argentina, Bahrain, Belarus, Chile, Columbia, Ecuador, Martinique, Iceland, Kuwait, Qatar, and Uganda) for the first time, thereby improving comparability and geographic diversity. Despite the limited representativeness of population-based cancer registry in many countries, findings based on subnational registries remain valuable for informing cancer control efforts in their often highly populated catchment areas. They also emphasise the need for continued support to implement and sustain population-based cancer registration in lower-resource settings.
Several important limitations should be noted. First, we acknowledge the underrepresentation of countries in CI5plus, particularly in Africa, Asia, and small islands where ongoing socioeconomic transitions are likely to increase colorectal cancer rates, yet detailed assessment remains scarce, due to the absence of population-based cancer registries. Second, 23 of the 50 populations in CI5plus have subnational coverage, and findings derived from these data might not be generalisable to entire countries. For instance, trends in India were based on data from four registries (Barshi, Chennai, Dindigul Ambilikkai, and Mumbai), representing only about 2% of the Indian population. A study of 14 registries, representing 5% of the Indian population, suggested increasing incidence in both age groups until 2014,33 inconsistent with our findings. Third, country-level analyses using aggregated data mask probably disparate trends among diverse sociodemographic groups within a country, warranting future studies to identify high-risk populations (eg, urban vs rural) and to inform targeted prevention policies. Fourth, some of the estimated trends are imprecise with wide CIs, indicating limited statistical power, especially in countries and territories with smaller populations. The absence of historical data in many countries weakens the ability to compare long-term trends across countries. Last, despite previous studies indicating a more pronounced increase in early-onset colorectal cancer for rectum in Canada, South Korea, and the USA3, 6 and colon cancer in and Australia, Denmark, and the UK,3 the present study does not provide site-specific trends. This was because we were unable to exclude appendiceal cancer (C18.1) from colon cancer,2 which probably overestimates the trend for colon cancer and could bias the comparisons. Considering differences in aetiologies and the effectiveness of screening,28 detailed and systematic analyses of subsite-specific trends are warranted to elucidate reasons behind the concerning trends.
The increase in early-onset colorectal cancer, previously seen predominately in high-income western countries, has now been documented in various economies and regions worldwide, marking it as a global phenomenon. The global reach of this alarming trend calls for innovative tools to prevent and control cancers linked to nutritional attributes, physical inactivity, and excess bodyweight, which might be more challenging to address than the tobacco epidemic. There is an urgent need for global initiatives and cross-country partnerships to identify the causes of early-onset colorectal cancer and implement effective preventive strategies that align with local resources and culture. Educational efforts to increase awareness of the increase in the incidence of early-onset colorectal cancer and its unique symptoms,29 especially among primary care providers, would have far reaching effects in reducing delayed diagnoses and mortality.
Contributors
Data sharing
Cancer Incidence in Five Continents Plus data are non-confidential and publicly accessible and can be extracted via the CI5plus website (https://ci5.iarc.fr/ci5plus/).
Declaration of interests
We declare no competing interests.
Acknowledgments
This work was funded by an Intramural Research Program of the American Cancer Society (to HS, RLS, CJ, and AJ). This work was delivered as part of the PROSPECT team supported by the Cancer Grand Challenges partnership funded by Cancer Research UK (CGCATF-2023/100037 to YC), the National Cancer Institute (1OT2CA297576-01 to YC), the French National Cancer Institute and the Bowelbabe Fund for Cancer Research UK. This work is in part supported by the National Institute of Health (R37CA246175 to YC). Where authors are identified as personnel of the International Agency for Research on Cancer (IARC)–WHO, the authors alone are responsible for the views expressed in this article, and they do not necessarily represent the decisions, policy, or views of the IARC–WHO.
Editorial note: The Lancet Group takes a neutral position with respect to territorial claims in published text, figures, tables, and institutional affiliations.
Acknowledgments
HS contributed to study conceptualisation, investigation, method, project administration, validation, and writing of the original draft and review and editing of the Article. ML contributed to the investigation, method, data curation, formal analysis, validation, designs of visualisation, and reviewing and editing of the Article. CJ contributed to the investigation, method, data curation, formal analysis, validation, designs of visualisation and reviewing and editing the manuscript. YC contributed to the literature review, investigation, and review and editing of the Article. RLS, EM, and MZ contributed to the investigation and reviewing and editing of the Article. FB and AJ contributed to the study conceptualisation, supervision, investigation, project administration, and reviewing and editing of the Article. HS and ML accessed and verified the underlying data. All authors had full access to all the data in the study, and final responsibility for the decision to submit for publication.
Supplementary Material
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Data Availability Statement
Cancer Incidence in Five Continents Plus data are non-confidential and publicly accessible and can be extracted via the CI5plus website (https://ci5.iarc.fr/ci5plus/).