Why Are More Young Adults Being Diagnosed with Colon Cancer?

Increasing Incidence of Colon Cancer Among Young Adults

The incidence of colon cancer in young adults, particularly those in their 20s and 30s, is on a concerning upward trend. This development contrasts with the traditional perception of colon cancer primarily affecting older individuals. 

Global Trends and Emerging Research

Recent analyses have shown a steady rise in the incidence of colon cancer among adults under 50 since the 1990s. The National Cancer Institute (NCI) acknowledges this increase, highlighting the need for research into the causes and risk factors specific to early-onset colorectal cancer​​. 

In a global study spanning from 2000 to 2012, researchers analysed data on various cancer types, including colon cancer, and found a consistent increase in incidence among adults before age 50. This study, led by Ogino and Tomotaka Ugai, emphasised the changing “exposome” in early life, which includes diet, lifestyle, environmental exposures, and microbiome changes. They suggest that these shifts, particularly in diet and lifestyle, might be contributing factors to the rise in early-onset cancers​​.

A systematic review conducted by BMC Cancer also supports these findings. It investigated worldwide trends in young-onset colorectal cancer (yCRC), reviewing various studies to understand the incidence patterns. This review highlighted the variability in reported trends across different regions, but consistently pointed towards an increasing incidence in younger populations​​.

Contributing Factors

Several key factors have been identified as contributing to the rising rates of colon cancer in younger adults. One crucial element is the accumulation of environmental chemicals. Some of these chemicals are known to cause cancer in the intestines of rodents. These include DNA-damaging agents and endocrine disruptors, which can lead to obesity, a known risk factor for colon cancer. The impact of these chemicals is complex, considering the multiple exposures individuals may encounter throughout their lives, including prenatal exposures​​.

In addition to environmental factors, changes in diet and lifestyle are significant contributors. The Western diet, characterised by high consumption of processed foods and sugary beverages, along with increased obesity, Type 2 diabetes, sedentary lifestyle, and alcohol consumption, has been linked to the rise in early-onset cancers. 

Genetic and Molecular Insights

There’s ongoing research to identify genes associated with a predisposition for colorectal cancer. With only about one-third of the approximately 20,000 human genes mapped to conditions, there’s significant scope for discovering new genetic markers that can predict an individual’s risk for diseases like colorectal cancer. 

Molecular tumour profiling, analysing DNA and other biological characteristics of tumour tissue samples, is also advancing, aiding in treatment decisions​​.

Screening and Early Detection

Screening for colon cancer is a crucial element in combating the rising incidence among young adults. Current guidelines and practices need to be reassessed in light of these demographic shifts.

Updated Screening Recommendations

Medical organisations, recognising the trend of increasing colon cancer rates in younger adults, have begun to adjust screening guidelines. For example, the recommended age to start colorectal cancer screening has been lowered from 50 to 45 by some organisations. This change aims to improve early detection, especially among those at higher risk due to lifestyle, family history, or environmental exposures​​.

Precision Screening

For individuals younger than 45, “precision screening” is being considered. This approach tailors colorectal cancer screening to each person based on their unique risk factors. By focusing on individual risk profiles, screening can be more efficient and cost-effective. Identifying specific molecules that drive the growth of early-onset tumours could enhance screening and diagnostic tests, making them more effective for younger adults​​.

The Role of Colonoscopy

Although the overall incidence of colorectal cancer in young people may still be too low to justify routine colonoscopies for them, it remains the gold standard for diagnosing colorectal cancers. Those with symptoms or a family history of the disease may need to undergo colonoscopy screenings earlier than the general guidelines suggest. Regular physical exams can also play a role in early detection​​.

Recognising Early Warning Signs

Young adults should be vigilant about changes in their health that could indicate early signs of colon cancer. Awareness of these symptoms is key to seeking timely medical attention.

  • Rectal Bleeding: Including blood in the stool or in the toilet after a bowel movement.
  • Changes in Stool Appearance: Such as dark, black, narrow, thin, or ribbon-like stools, which may indicate an obstruction or bleeding from a tumour.
  • Changes in Bowel Movements: Persistent diarrhoea or constipation, especially if lasting more than two weeks.
  • Low Energy or Tiredness: This could be a sign of anaemia from blood loss, often associated with colorectal cancer.

It’s essential for individuals, even in their 20s and 30s, to consult with healthcare professionals if they experience any of these symptoms. Early detection can significantly improve treatment outcomes​​.

The rise in colon cancer among young adults is a complex issue that intertwines genetic, environmental, dietary, and lifestyle factors. Addressing this challenge necessitates a multifaceted approach that includes revising screening guidelines, enhancing public awareness, and encouraging lifestyle modifications. By understanding and responding to these factors, we can improve prevention, early detection, and treatment, ultimately reducing the impact of this disease on younger populations.


  1. Colorectal Cancer Rising among Young Adults. (2020, November 5). National Cancer Institute.
  2. G., & G. (2024, January 10). Dramatic rise in cancer in people under 50. Harvard Gazette.
  3. Din, K. S. E., Loree, J. M., Sayre, E. C., Gill, S., Brown, C. J., Dau, H., & De Vera, M. A. (2020, April 6). Trends in the epidemiology of young-onset colorectal cancer: a worldwide systematic review. BMC Cancer.
  4. Katella, K. (2024, January 17). Colorectal Cancer: What Millennials and Gen Zers Need to Know. Yale Medicine.

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