Why more young adults are being diagnosed with colon cancer: Oncologist Dr Ravi K Gupta shares risk factors and symptoms

Colon cancer is increasingly affecting younger adults. Oncologist explains the lifestyle factors behind the rise, warning signs and when to get screened.

For decades, colorectal cancer was considered a disease that primarily affected older adults. However, that trend is changing. According to experts, an increasing number of younger people are now being diagnosed with the disease, prompting greater awareness about lifestyle-related risk factors and the importance of early screening.

Speaking about the growing concern, oncologist Dr Ravi K Gupta shared on an August 2 Instagram post, "Over the past 30 years, colorectal cancer has been steadily rising in younger adults across the world. Today, nearly one in five new colorectal cancer cases are diagnosed in people under the age of 55, highlighting a worrying shift in disease patterns."

How has the gut microbiome changed

According to Dr Gupta, one possible explanation lies in changes to the gut microbiome, the trillions of bacteria that live inside the digestive tract and play a crucial role in overall health.

"Research suggests that low dietary fibre intake, frequent consumption of ultra-processed foods and repeated exposure to antibiotics may alter the gut microbiome. Certain bacterial species, including some strains of E. coli and Fusobacterium nucleatum, have been linked to colorectal cancer in scientific studies," he explained.

Dietary habits have also changed significantly over the past few decades. "Compared to previous generations, people today consume far more ultra-processed foods, sugary beverages and calorie-dense meals, while eating much less fibre. Large population studies have consistently associated a higher intake of ultra-processed foods with an increased risk of colorectal cancer, particularly among men," Dr Gupta said.

Metabolic health plays a key role

Poor metabolic health may also contribute to the rising incidence of early-onset colorectal cancer.

"People living with obesity, type 2 diabetes, insulin resistance or low levels of physical activity appear to have a higher risk. These conditions can promote chronic inflammation and hormonal changes, including elevated insulin and insulin-like growth factor-1 (IGF-1), which researchers believe may influence cancer development," he noted.

In response to the increasing number of cases among younger adults, screening recommendations have evolved. "Recognising this trend, the American Cancer Society lowered the recommended screening age for people at average risk from 50 to 45 years. Individuals with a strong family history of colorectal cancer, inflammatory bowel disease or hereditary cancer syndromes may need to begin screening even earlier," Dr Gupta said.

Symptoms that should never be ignored

While the majority of people under 50 will never develop colorectal cancer, experts stress that age should not be a reason to dismiss warning signs.

"Symptoms such as blood in the stool, a persistent change in bowel habits, unexplained weight loss and iron-deficiency anaemia should always be evaluated by a healthcare professional. Being young should never delay medical assessment if these symptoms are present," Dr Gupta emphasised.

Although colorectal cancer remains relatively uncommon in younger adults, its rising incidence underscores the importance of healthy lifestyle habits, including eating a fibre-rich diet, limiting ultra-processed foods, staying physically active and seeking timely medical evaluation for persistent digestive symptoms. Early detection remains one of the most effective ways to improve outcomes.

Dr Ravi K. Gupta is a board-certified internist and a haematology and medical oncology fellow in Miami, USA. He completed his MBBS from PGIMS Rohtak and earned his MD in Internal Medicine from Larkin Medical System, where he also served as Chief Resident.

Note to readers: This article is for informational purposes only and not a substitute for professional medical advice. Always seek the advice of your doctor with any questions about a medical condition.

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