Over the past decade, colorectal cancer specialist Dr Amanjeet Singh, the senior director of GI Surgery and GI Oncology, Gastrosciences at Medanta, Gurugram has observed a shift in the kinds of patients coming to him. He noted that more people in their 30s and 40s in India were developing colorectal cancer at a faster rate than their peers in Western countries.
He said that when he began examining their lifestyle habits, a clear pattern emerged: frequent consumption of fast food and ultra-processed meals, reliance on ready-made and heat-and-eat options, long hours of sedentary desk work, minimal physical activity, and poor sleep.
According to him, many of his younger patients showed similar eating behaviours, often eating out or ordering food online. Because of these recurring patterns, he has come to describe colorectal cancer as a lifestyle-driven disease.
A recent study in JAMA Oncology appears to support his concerns. The research builds on the work of Dr. Andrew T. Chan, a gastroenterologist at Mass General Brigham in Boston, whose findings suggest that a rise in colorectal cancer corresponds with increased consumption of ultra-processed foods.
He and his team examined data from women nurses in their 20s to 40s, finding that those who regularly consumed sugary beverages, fried items, processed meats, chips, candies, and sodas were more likely to develop pre-cancerous polyps — abnormal cell clusters in the colon or rectum that can precede cancer, Indian Express reported.
Dr Amanjeet Singh explains that ultra-processed foods can disturb the balance of gut microbes, which is essential for protecting the intestinal lining. He notes that when this lining becomes damaged, toxins can pass through the gut barrier and trigger inflammation. According to him, such inflammation can cause abnormal cell activity and lead to the formation of benign tumours, known as adenomas, in the lower gastrointestinal tract — some of which may eventually become cancerous.
He says that relying heavily on ultra-processed and heat-and-eat foods also means consuming very little fibre. In contrast, diets rich in fruits, vegetables, and home-cooked meals provide more fibre, which he describes as functioning like a “scrub brush” that helps clean the colon by removing harmful bacteria and accumulated waste, thereby lowering the risk of colon cancer.
When asked which ultra-processed foods pose the greatest risk, Dr Singh points to processed meat, poultry, and fish. He notes that minced or mechanically processed meats can contain phthalates — industrial chemicals that enter food during processing and packaging.
He also refers to the WHO’s classification of processed meat as a Group 1 carcinogen, meaning there is strong evidence linking it to cancer. He adds that the nitrites and nitrates used as preservatives in these products can form cancer-causing compounds during cooking.
Regarding polyps, Dr Singh clarifies that although not every polyp becomes cancerous, all colorectal cancers begin as polyps, which is why they are removed whenever detected. He says that in younger people, these growths are often mistaken for haemorrhoids, and without proper screening, a potentially cancerous polyp can remain unnoticed. He points out that colorectal cancer develops slowly and its symptoms often resemble other gastrointestinal issues, making early identification difficult.
On the question of screening in India, he says there are no country-specific guidelines. However, he explains that a colonoscopy performed for conditions like piles or fissures can also help detect precancerous lesions. He reiterates that colorectal cancer tends to affect Indians nearly a decade earlier than those in Western populations.
He notes that in the United States, the recommended age for routine screening in asymptomatic individuals was lowered from 50 to 45 once cases among younger people increased. For those with a first-degree relative who has had colorectal cancer, he advises beginning screening five years earlier than the affected family member’s age at diagnosis — or at age 40, whichever comes first.