Childhood bacteria exposure linked to the surge in young adult colon cancer diagnoses, study finds

Key takeaways:

• Bacterial exposure increasing cancer risk: The study found that exposure to a toxic bacteria, colibactin, in childhood may increase the likelihood of developing colon cancer earlier in life. 

• Global data analysis: The researchers analyzed the DNA structure of nearly 1,000 colon cancer tumors ranging from low-risk to high-risk cases to better understand how certain mutations could increase the risk of development. 

• The risk of colibactin: Experts found that DNA mutations specific to colibactin exposure were over three times as common in young adults diagnosed with colon cancer. They hope to do more work in this area to better understand the health risks. 

A new study conducted by researchers from UC San Diego explored how exposure to a specific bacteria in childhood could be behind the surge in colon cancer diagnoses among young adults. 

They found that the bacterial toxin colibactin could lead to the specific cell mutation that causes colon cancer. 

“When we started this project, we weren’t planning to focus on early-onset colorectal cancer,” study first co-author Marcos Díaz-Gay said in a news release. 

“Our original goal was to examine global patterns of colorectal cancer to understand why some countries have much higher rates than others. But as we dug into the data, one of the most interesting and striking findings was how frequently colibactin-related mutations appeared in the early-onset cases.”

The study

One of the primary goals of the study was to determine whether DNA mutations have contributed to the increase in colon cancer diagnoses. 

The researchers analyzed data samples from nearly 1,000 patients with colorectal cancer. The patients ranged in age from 40 to 70 and were all at varying disease risk levels. 

The impact of colibactin 

Ultimately, the researchers identified colibactin, a toxic bacteria that’s produced by certain strains of E.coli, as the link between the recent surge in colon cancer diagnoses in young adults. 

The study found that colibactin caused a specific kind of DNA mutation that was much more prevalent in early-onset colon cancer cases. Specifically, adults under 40 were over three times as likely to experience this DNA mutation compared to those who were diagnosed over the age of 70. 

These findings were also true in countries where rates of colon cancer are highest, including the U.S. 

“These mutation patterns are a kind of historical record in the genome, and they point to early-life exposure to colibactin as a driving force behind early-onset disease,” said study senior author Ludmil Alexandrov. 

Risks in early life

The findings showed that colibactin starts affecting the body early on. The researchers looked at when certain gene mutations occurred, and they learned that those linked to colibactin showed up early in tumor growth — sometimes even in the first 10 years of life. 

They also discovered that about 15% of the early gene changes that help cancer grow, called APC driver mutations, are connected to colibactin in colorectal cancer.

“If someone acquires one of these driver mutations by the time they’re 10 years old, they could be decades ahead of schedule for developing colorectal cancer, getting it at age 40 instead of 60,” Alexandrov said. 

Areas for future research

While this study found an association between colibactin and colon cancer, the findings didn’t point to a specific cause and effect relationship. However, the researchers hope to do more work in this area to better understand where colibactin exposure comes from, and how we can protect ourselves. 

“This reshapes how we think about cancer,” Alexandrov said. “It might not be just about what happens in adulthood — cancer could potentially be influenced by events in early life, perhaps even the first few years. Sustained investment in this type of research will be critical in the global effort to prevent and treat cancer before it’s too late.”