Rising Concerns Over Early-Onset Cancers and Colibactin Exposure

Recent years have seen an alarming increase in early-onset cancers—those diagnosed in adults younger than 50—around the world, including the United States. Among these, early-onset colorectal cancers have been particularly concerning. According to the American Cancer Society, the incidence of colorectal cancer in U.S. adults younger than 55 increased by 1% to 2% each year from 2015 to 2019. Those born around 1990 have double the risk of developing colon cancer and quadruple the risk of rectal cancer compared to those born in 1950.  

Colibactin: A Possible Contributor  

Colibactin, a toxin produced by certain E. coli strains found in the digestive system, is suspected to play a role in early-onset colorectal cancer. It is estimated that about 20% of healthy individuals, and 31% of infants, harbor these colibactin-producing bacteria. This toxin is known for its ability to damage DNA, and studies have suggested a link between colibactin-related mutations and some colorectal cancer cases.  

A study published in Nature analyzed nearly 1,000 colorectal cancer samples from 11 countries and found DNA mutations associated with colibactin were 3.3 times more common in cancers diagnosed before age 40 compared to those diagnosed after age 70. This suggests that exposure to colibactin early in life could set the stage for colorectal cancer decades later.  

Challenges and Further Research  

While the study presents compelling evidence of a link between colibactin and early-onset colorectal cancer, it does not establish causation. Additional research is needed to fully understand environmental or lifestyle changes that might have increased colibactin exposure over recent decades. Other factors like diet, BMI, and exercise also need to be considered.  

Dr. Ludmil Alexandrov and his team plan to explore how children are exposed to colibactin and whether interventions like probiotics could offer protection. They are also working on developing a stool test for colibactin-related damage to improve early detection and monitoring.  

Practical Steps to Reduce Colorectal Cancer Risk  

Despite the ongoing research, there are proactive measures people can take to lower colorectal cancer risk. Limiting the intake of red and processed meats, sugar, and refined grains can help, along with consuming more vegetables, beans, and whole grains. Adopting a healthy lifestyle that includes regular exercise, avoiding tobacco and excessive alcohol, and maintaining a balanced diet from a young age are crucial steps.  

The Centers for Disease Control and Prevention recommends routine colorectal cancer screenings for adults starting at age 45, including colonoscopies, to aid early detection. As researchers continue to study early-onset colorectal cancers, focus on health practices that promote lifelong wellness becomes increasingly important, particularly from childhood, as early-life factors can have long-term health impacts.