The rising trend
Potential causes
Screening and early detection
Future Directions
Colorectal cancer (CRC) is a leading global health concern, ranking as the third most diagnosed cancer and the second leading cause of cancer-related mortality. Historically, CRC has been considered an age-related disease, primarily affecting individuals over 50 years. This trend was largely influenced by lifestyle factors and the implementation of widespread screening programs, which contributed to declining incidence rates among older adults in many high-income countries.
However, recent decades have witnessed a concerning shift, with CRC incidence rising among younger adults (under 50 years). This increase is particularly evident in high-income nations like the United States (U.S.), Australia, and parts of Europe, but it is also emerging in Asian and Latin American countries.
The changing epidemiology of CRC highlights the need for further investigation into potential risk factors, including diet, lifestyle, and genetic predisposition. Understanding these evolving patterns is crucial for developing targeted prevention and early detection strategies to address the growing burden of early-onset CRC.1
This article explores the rising incidence of CRC among young adults, investigating possible causes, risk factors, and preventative strategies.
Image Credit: NMK-Studio/Shutterstock.com
The rising trend
CRC is a growing concern among younger populations in the United States. According to the American Cancer Society, while overall CRC mortality has declined, cases among individuals under 50 have steadily increased.
In 2023, approximately 19,550 people under 50 were diagnosed with CRC, and 3,750 deaths occurred in this age group. The proportion of CRC cases in individuals under 55 has nearly doubled from 11% in 1995 to 20% in 2019.2
More diagnoses at advanced stages accompany this shift. From 2010 onward, regional-stage cases increased by 2%-3% annually in those under 65 and distant-stage cases by 0.5%-3%. The trend reverses previous progress in early-stage detection due to widespread screening. Rectal cancer cases, in particular, have risen, with their share of total CRC diagnoses growing from 27% in 1995 to 31% in 2019.2
Despite overall mortality declining, younger individuals are experiencing an increase in CRC deaths by 0.5%-3% annually. The reasons behind this rise remain uncertain but may include lifestyle changes, diet, obesity, and genetic factors.
Addressing this growing crisis requires improved early detection strategies and equitable access to screening and treatment, particularly for high-risk groups.2
Colorectal Cancer Symptoms
Potential causes
Epidemiological data show that Westernized diets high in red and processed meats and low in fiber- contribute significantly to CRC risk. High consumption of red meat increases gut microbiota-derived metabolites such as trimethylamine-N-oxide (TMAO) and secondary bile acids, which promote inflammation and carcinogenesis. In contrast, fiber-rich diets enhance short-chain fatty acid (SCFA) production, reducing inflammation and strengthening the gut barrier, thus lowering CRC risk.3,4
The gut microbiome plays a pivotal role in CRC development. Dysbiosis (an imbalance in gut microbial composition) has been linked to CRC. Studies have identified specific microbial strains, such as Fusobacterium nucleatum and Bacteroides fragilis, that promote tumorigenesis by triggering inflammatory pathways and immune evasion. Conversely, beneficial bacteria like Faecalibacterium prausnitzii and Bifidobacterium help maintain gut homeostasis and may protect against CRC.3,4
Obesity, physical inactivity, smoking, and excessive alcohol consumption are well-established lifestyle risk factors for CRC. Obesity alters gut microbiota composition and increases systemic inflammation, which fosters a pro-carcinogenic environment.
Physical activity, on the other hand, has been shown to modulate the microbiome favorably and reduce CRC risk. Additionally, environmental exposures, such as antibiotic overuse, may disrupt microbial diversity, potentially increasing susceptibility to CRC.3,4
While environmental and lifestyle factors play significant roles, genetic predisposition also influences CRC risk. Individuals with Lynch syndrome or familial adenomatous polyposis (FAP) have a much higher lifetime risk of CRC.
Additionally, genome-wide association studies have identified multiple genetic variants associated with increased susceptibility to CRC, often interacting with dietary and microbial factors.3
Moffitt Medical Minute (Ep. 48) - Why is Colorectal Cancer Rising in Young Adults and Millennials?
Screening and early detection
CRC is increasingly affecting younger individuals, yet they are often diagnosed at later stages, resulting in poorer outcomes. According to the American Cancer Society, CRC incidence in individuals under 55 has been rising by 1%-2% annually since the mid-1990s, with mortality rates growing at a similar pace.
This delay in diagnosis is primarily due to lower screening rates, misattributed symptoms, and a lack of awareness among both patients and healthcare providers.5,6
Several factors contribute to the late-stage diagnosis of CRC in younger individuals. First, CRC screening guidelines have traditionally focused on adults, with routine screenings recommended only after 45.
Consequently, younger individuals experiencing symptoms such as rectal bleeding or abdominal pain may not seek immediate medical attention, and healthcare providers may not prioritize CRC screening for them. Misdiagnoses, often attributing symptoms to less severe conditions like hemorrhoids or irritable bowel syndrome, further delay detection.5,6
Early screening significantly improves survival rates, with stage I CRC having a 91% five-year survival rate compared to only 14% for stage IV cases. Recent advancements in screening tools, including fecal immunochemical tests (FIT), multi-target stool Deoxyribonucleic acid (DNA) tests, and colonoscopies, enhance early detection. Emerging technologies such as liquid biopsies and artificial intelligence (AI)-assisted diagnostics hold promise for increasing accessibility and accuracy.5,6
Despite the benefits, screening adherence remains low due to financial constraints, fear, and lack of awareness. Expanding screening programs, increasing physician recommendations, and promoting non-invasive tests can improve compliance. Additionally, policy changes that eliminate cost-sharing barriers for preventive screenings can have a significant impact.5,6
Cancer Screening Considerations: Balancing the Benefits and Risks
Future directions
Traditionally considered a disease of older adults, CRC now increasingly affects individuals under 50. Studies suggest genetic predispositions, microbiome alterations, and dietary habits play a role in this trend.
Advances in molecular diagnostics, including liquid biopsy and AI-assisted imaging, are revolutionizing early detection. For instance, blood-based tests analyzing circulating tumor DNA (ctDNA) are showing promise as non-invasive diagnostic tools. Additionally, AI is improving the accuracy of colonoscopy screenings, reducing false negatives, and enhancing early intervention efforts.7
A multi-pronged approach to prevention is critical in addressing CRC and other chronic diseases. Lifestyle modifications remain the cornerstone of prevention. Research emphasizes the impact of diet, physical activity, and environmental exposures on CRC risk.
High consumption of processed meats, low fiber intake, and sedentary lifestyles significantly contribute to rising cancer cases. Conversely, a diet rich in whole grains, lean proteins, and vegetables, coupled with regular exercise, reduces risk.7
Environmental factors also play a significant role. Increased exposure to microplastics, endocrine disruptors, and processed foods affects gut microbiota composition, leading to chronic inflammation. Public awareness campaigns promoting gut health and microbiome diversity through probiotic and prebiotic-rich diets can mitigate risk.7
Governments and healthcare agencies worldwide are adapting policies to address these rising health concerns. In response to growing CRC incidence in younger adults, screening age recommendations have been lowered from 50 to 45 in several countries.
Implementing universal screening programs with non-invasive options, such as FIT, can improve participation rates. Additionally, policy reforms focus on reducing disparities in healthcare access. Telemedicine and digital health platforms are expanding preventive care outreach, particularly in underserved populations. Governments are also emphasizing regulatory measures on food labeling, restricting carcinogenic additives, and promoting healthier food environments.1,7
The future of disease prevention lies in integrating scientific research with practical public health strategies and evidence-based policies. A combination of technological advancements, lifestyle modifications, and comprehensive policy changes can significantly curb CRC incidence and improve overall health outcomes.
Strengthening early detection methods, fostering preventive healthcare, and ensuring equitable access to medical resources are essential in shaping a healthier future.
References
1. Sung, H., Siegel, R. L., Laversanne, M., Jiang, C., Morgan, E., Zahwe, M., ... & Jemal, A. (2025). Colorectal cancer incidence trends in younger versus older adults: an analysis of population-based cancer registry data. The Lancet Oncology, 26(1), 51-63. https://doi.org/10.1016/S1470-2045(24)00600-4
2. Siegel, R. L., Wagle, N. S., Cercek, A., Smith, R. A., & Jemal, A. (2023). Colorectal cancer statistics, 2023. CA: a cancer journal for clinicians, 73(3), 233-254. https://doi.org/10.3322/caac.21772
3. Song, M., Chan, A. T., & Sun, J. (2020). Influence of the gut microbiome, diet, and environment on risk of colorectal cancer. Gastroenterology, 158(2), 322-340. https://doi.org/10.1053/j.gastro.2019.06.048
4. Saha, B., AT, R., Adhikary, S., Banerjee, A., Radhakrishnan, A. K., Duttaroy, A. K., & Pathak, S. (2024). Exploring the Relationship Between Diet, Lifestyle and Gut Microbiome in Colorectal Cancer Development: A Recent Update. Nutrition and Cancer, 76(9), 789-814. https://doi.org/10.1080/01635581.2024.2367266
5. Aleissa, M., Drelichman, E. R., Mittal, V. K., & Bhullar, J. S. (2024). Barriers in early detection of colorectal cancer and exploring potential solutions. World Journal of Clinical Oncology, 15(7), 811. https://doi.org/10.5306/wjco.v15.i7.811
6. Adigun, A. O., Adebile, T. M., Okoye, C., Ogundipe, T. I., Ajekigbe, O. R., Mbaezue, R. N., & Okobi, O. E. (2023). Causes and prevention of early-onset colorectal cancer. Cureus, 15(9). https://doi.org/10.7759/cureus.45095
7. Shaukat, A., & Levin, T. R. (2022). Current and future colorectal cancer screening strategies. Nature reviews Gastroenterology & hepatology, 19(8), 521-531. https://doi.org/10.1038/s41575-022-00612-y
Further Reading