June 26, 2026, 3:07 pm | Read time: 7 minutes
People without a family history of risk are generally advised to start colorectal cancer screening at around age 50, as it was long considered a disease of older age. However, this perception has changed. A new analysis of German cancer registries shows that the number of colorectal cancer diagnoses among younger adults is increasing. This trend is particularly pronounced among those aged 20 to 29. Overall, the study presents a nuanced picture: The data do not necessarily suggest that the screening age needs to be lowered.
Colorectal Cancer Increasing Among Younger Adults in Germany
Recently, an international review compiled numerous studies from various countries, as reported by FITBOOK.1 It concluded that colorectal cancer and other gastrointestinal cancers are on the rise among younger people (under 50) worldwide.
The new study took this a step further.2 The research team, led by cancer epidemiologist Dr. Sven Voigtländer, analyzed cancer registry data from Germany spanning over 20 years for the first time. This allows for a more precise assessment of the trend in this country.
Study Details
In recent years, studies from the U.S. have drawn attention by showing a significant increase in cancer cases among younger people.3 Some types were particularly prevalent among women. Analyses were also available for Germany, but they often focused on individual states or did not sufficiently differentiate between various tumor types and locations.
This study, therefore, examined the development of early-onset colorectal cancer (EO CRC) on a national level in Germany over 21 years. The researchers specifically looked at whether certain age groups are more affected. The study also focused on which specific tumor types are increasing and how Germany compares to the U.S.
Another focus of the registry study was distinguishing between different tumor types. This helps determine whether the number of cases is truly rising or if the apparent trend is due to improved diagnostics or changed classifications. For context: Neuroendocrine tumors, which originate from hormone-producing cells, often progress less aggressively than the more common adenocarcinomas.
Study Design and Methods
The researchers analyzed registry data of colorectal cancer cases in Germany from 2003 to 2023. Only regions with complete and high-quality cancer registration were considered. Overall, the analysis covers about 46 percent of the German population.
Specifically, the analysis included 28,046 colorectal cancer cases among 27,568 individuals aged 20 to 49. All new cases of colorectal cancer (ICD-10 C18 to C20) were examined. Tumors of the appendix have specific biological characteristics, so the researchers evaluated them separately.
The researchers calculated age-standardized incidence rates and their average annual percent change (AAPC). This was to illustrate how the numbers have developed over the years, independent of changes in the population’s age structure. The data were analyzed by gender, in different age groups (20–29, 30–39, and 40–49 years), by tumor location and type, tumor size, and differentiation grade. For international comparison, the researchers also used data from the U.S. SEER cancer registry.
Also of interest: Colorectal Cancer – Early Symptoms and Signs of Advanced Disease
Results
The analysis showed that between 2003 and 2023, the age-standardized incidence rate slightly increased for both men and women. On average, the increase was about 0.8 percent per year for men and 0.9 percent for women.
The trend did not affect all age groups equally. The increase in cases was particularly pronounced among those aged 20 to 29. Here, the number of cases rose by an average of 3.3 percent per year for men and 3.9 percent for women. In the 30 to 39 age group, there was also a clear increase, with a rise of 2.2 percent (men) and 2.0 percent (women). In the 40 to 49 age group, however, the incidence rate remained largely stable.
Increase in Tumors with Better Prognosis
When examining the different tumor types, it was confirmed that about 90 percent of all diagnoses were adenocarcinomas. However, the number of neuroendocrine neoplasms also increased significantly. This is favorable, as these tumors are often associated with a better prognosis. More small and low-grade tumors, which tend to be less aggressive, were also diagnosed.
Overall mortality remained largely stable or even slightly decreased in some age groups. This suggests that the number of diagnoses has increased more than the number of deaths. Briefly on the international comparison: In the U.S., incidence rates among younger adults were already significantly higher at the start of the study than in Germany and increased much more sharply over time.
Significance of the Results
The increase in tumors with a relatively favorable prognosis could indicate that more cases are being detected earlier. However, an exact quantification with the available data is not possible. This is according to FITBOOK in a conversation with Aleksander Szumilas, spokesperson for the responsible working group at the Bavarian State Office for Health and Food Safety (LGL). However, several findings suggest a significant effect of earlier diagnosis: Small tumors (T1) and well-differentiated tumors (low grading) have become disproportionately more common. This disproportionate increase is also reflected in higher average annual percent changes compared to the overall cohort.
Additionally, the authors point out that mortality rates, unlike incidence rates, have remained largely stable–a pattern visible in the study through the dashed lines in Figure 2. “This suggests that more tumors are being detected earlier without leading to a corresponding increase in mortality,” they explain.
Lifestyle Factors That Could Play a Role
The notable stability of incidence rates among those aged 40 to 49 could be influenced by lifestyle factors, particularly differences in overweight, obesity, physical inactivity, and dietary patterns. A possible screening effect is also discussed, as in the U.S., colorectal cancer screening is sometimes recommended starting at age 45, while in Germany, it traditionally begins later. Additionally, other early life factors are mentioned as potentially relevant, including antibiotic use, dietary patterns with a high proportion of ultra-processed foods, and their possible effects on the gut microbiome.
Regarding the causes of the increase in the 20 to 39 age group, the team advocates for a broad, integrated research perspective. The interplay of various influences is crucial, rather than a single factor. Future studies should examine both early-life lifestyle factors and their effects on the gut flora. They should also consider possible interactions with genetic or familial predispositions that could mutually reinforce each other.
More and More Cases of Stomach Cancer in People Under 50
Annual Breast Cancer Deaths Are Expected to Rise by 68 Percent by 2050
Should More Younger Adults Undergo Colorectal Cancer Screening?
In light of the current data, the study authors emphasize that early detection should continue to focus on risk groups. They see no reason for a general lowering of the screening age, as colorectal cancer remains relatively rare among younger adults. According to a press release, about five percent of the approximately 56,000 new colorectal cancer cases annually occur in people under 50.4
Limitations
As this is purely an observational study, no conclusions about cause and effect can be drawn. The study only shows the temporal developments in incidence rates.
It should also be noted that while the analysis covers about half of the German population, it does not include all federal states, leaving regional differences unconsidered.
Additionally, cancer registry data are based on reported diagnoses. Changes in diagnostics, classification, or reporting behavior can influence long-term trends. The authors have attempted to minimize such effects by separately analyzing different tumor types.
Another limitation is that part of the increase is likely due to earlier diagnosis of smaller and biologically less aggressive tumors. At the same time, the increase in advanced tumors among younger adults and international differences suggest that the actual risk of disease may have changed.