Why Colorectal Cancer is Rising in Singapore and Globally & What We Can Do About It
- Alastair Hunt
- May 2
- 7 min read
Updated: Jul 8
Colorectal (bowel) cancer is no longer confined to older adults. In Singapore and across the world, more people under the age of 50 are being diagnosed with colorectal cancer (CRC) and many of these cases are detected at advanced stages. What’s driving this trend - and what can we do to turn it around?
Recent research from Asia, Europe, and global meta-analyses reveals a common thread: lifestyle, biology and public health systems are deeply intertwined in shaping early-onset colorectal cancer risk. Understanding these connections is vital to protecting future generations.
During the period from 2018 to 2022 in Singapore, the three most frequent incident cancers reported for males were: prostate (17.4%; learn more here), colorectal (16.2%), and lung (13.4%). In the UK, colorectal cancer is the third most common cancer among males, accounting for 14% of all new cancer cases in men (2017–2019).
As ever, please talk to your doctor or medical practitioner most familiar with your medical history before implementing any changes in diet, exercise or lifestyle, especially if you are under treatment. Links to all studies at bottom of page.
A Global Trend, With Local Lessons
Singapore provides a telling case of how early-onset colorectal cancer (EOCRC) is evolving in Asia. A comprehensive 50-year analysis of national cancer data from 1968 to 2019 revealed that while age-standardised CRC rates among older adults (especially those over 65) have declined - largely due to the introduction of national screening in 2011 - rates in adults aged 20 to 49 have continued to climb. This rise was particularly sharp for rectal cancer, which increased at an annual rate of 1.5% among younger men. Among ethnic groups, Malays experienced the most significant increase in both colon and rectal cancer incidence, likely reflecting differences in diet, obesity rates, and participation in screening programmes.
This trend is not unique to Singapore. In the United States, EOCRC incidence in adults aged 20 to 49 has risen steadily since the 1990s. Rectal cancer in this group increased by 2.3% annually, while colon cancer rose by 1.3% per year. Australia and South Korea report similar patterns, with EOCRC growing faster than any other age group. In Europe, countries such as the United Kingdom and the Netherlands have observed comparable increases, particularly in adults aged 40 to 49.
One unifying factor across these regions appears to be birth cohort. Individuals born after 1970 - who are now in their 40s and early 50s - show consistently higher CRC incidence than earlier generations. This suggests that environmental and behavioural shifts that began in the late 20th century, including increased consumption of ultra-processed foods, reduced physical activity in childhood, rising childhood obesity, and changes in the gut microbiome, may have established long-term cancer risk.
The Singapore data, along with global trends, underscore the urgency of updating screening policies and health education to reflect the changing face of CRC.
Learn More: Red Meat, Cancer Risk and the Power of Plants: What Six Major Studies Reveal about Colorectal Cancer
The Impact of Lifestyle: More Than Just Association
A major global review, covering over a million people, found that those with the healthiest lifestyles had roughly half the risk of developing CRC compared to those with the poorest habits. Each additional healthy behaviour - such as regular exercise, not smoking, eating a fibre-rich diet, and maintaining a healthy weight - reduced risk by nearly 9%.
What makes these findings more urgent is that few people follow multiple healthy behaviours. In one study, fewer than 6% of adults in Europe adhered to all major cancer-preventive guidelines. Similar trends are emerging in Asia, where urbanisation is rapidly changing diets and activity patterns.
To establish causation rather than correlation, researchers have turned to genetic studies. A 2024 Mendelian randomisation study in Europeans confirmed that higher waist-to-hip ratio, more so than body mass index, causally increases CRC risk. Smoking also showed a clear genetic link to higher risk. In contrast, no strong evidence was found for alcohol or physical activity in this particular analysis, though these factors are supported in broader cancer prevention literature.
What Else Is Driving Risk?
Several emerging factors are shaping CRC risk globally. Ethnic disparities in screening uptake and lifestyle exposure - such as those seen in Singapore’s Malay population - highlight the need for culturally tailored public health efforts.
Changes to the gut microbiome, especially those triggered by poor diet and smoking, are also under scrutiny. Disruptions in microbial balance may increase inflammation and support tumour growth, suggesting the microbiome could become a future prevention target.
And for younger adults, delayed diagnosis remains a problem. Symptoms like blood in the stool or changes in bowel habits may be misattributed to minor digestive issues. Many younger patients also face significant psychological stress, fertility concerns, and financial hardship as they navigate treatment during formative life stages.
Prevention and Awareness: What You Can Do
Colorectal cancer is largely preventable, and the core advice for reducing risk remains remarkably consistent across regions and cultures. Speak to your doctor about testing.
Avoiding tobacco is one of the most effective measures; smoking not only increases the risk of CRC but also worsens outcomes for those diagnosed. Tobacco use contributes to inflammation and may alter the gut microbiome, both of which play a role in tumour development.
Managing abdominal fat is another critical factor. While general obesity is linked to increased CRC risk, it is central obesity - measured by waist-to-hip ratio - that appears to be a more specific and potent driver. Visceral fat stored around abdominal organs is metabolically active and can lead to chronic inflammation, insulin resistance and hormonal changes that promote cancer growth.
Diet plays a powerful role. A high intake of dietary fibre from whole grains, legumes, fruit and vegetables not only helps regulate digestion and prevent constipation but may also reduce inflammation and support a healthier microbiome. Conversely, frequent consumption of red meat - especially processed varieties like sausages, ham and bacon - has been linked to a higher CRC risk. This is due in part to the formation of carcinogenic compounds such as nitrosamines and heterocyclic amines during meat processing or high-temperature cooking.
Regular physical activity is widely recommended, not just for general health but also for specific CRC protection. Exercise helps maintain a healthy weight, supports bowel regularity, and improves immune surveillance. Even modest activity - like brisk walking for 30 minutes most days - has been associated with reduced CRC risk, especially among sedentary populations.
Ultimately, while no single lifestyle change guarantees prevention, the cumulative effect of these behaviours can dramatically lower both the incidence and severity of colorectal cancer across different populations.
Perhaps most importantly, take persistent gastrointestinal symptoms seriously - especially if you're under 50. Don’t wait to seek medical advice. In many countries, CRC screening begins at age 50, but guidelines are shifting. The U.S. now recommends screening from age 45, and in countries like Singapore, options like faecal testing and flexible sigmoidoscopy are available.
Final Thoughts
The rise of early-onset colorectal cancer is not a fluke - it’s a global phenomenon with clear links to lifestyle, early-life exposures, and gaps in screening. While the research continues to evolve, the path forward is already clear: better awareness, healthier habits and broader access to early detection tools.
Singapore’s experience is a powerful reminder that even high-income nations are vulnerable when public health doesn’t adapt quickly to demographic and behavioural change. Globally, we now have the data - and the tools - to act. Early detection saves lives. But prevention still saves the most.
Changing health for the better is about progress, not perfection, and even small changes can have a powerful and positive effect on health. For most people, improving health is about finding motivation and prioritising self-care - with an ultimate goal of taking action. If you want to take effective and targeted steps that fit into your unique lifestyle and circumstances, The Whole Health Practice is here to help.
Whether your interest is healthspan and longevity, to beat chronic illness or to enhance your mental health and well-being, our consultations and programs deliver results that are tailored to your needs.
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Stay Healthy,
Alastair
See our articles on prostate and breast cancer.
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Related Studies
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Li, X., Chang, Z., Wang, J. et al. Unhealthy lifestyle factors and the risk of colorectal cancer: a Mendelian randomization study. Sci Rep 14, 13825 (2024). https://doi.org/10.1038/s41598-024-64813-y
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