A recent study published in Nature has found a strong link between the bacterial toxin colibactin and colon cancer among younger patients. Researchers analyzed tissue samples from nearly 1,000 colorectal cancer patients across four continents and discovered that most had cancers bearing mutations that signaled a past encounter with colibactin.
The study’s lead author, Ludmil Alexandrov, explains that colibactin is like the “weapon system” of certain bacteria to fight other bacteria and defend themselves. Those under 40 with early-onset colon cancer were three to five times more likely to have these mutations than those in their 70s and older.
The researchers believe that this bacterial weaponry can get directed at gut cells, seeding mutations that put individuals at increased risk of developing colorectal cancer. According to their data, exposure to colibactin isn’t ongoing when the cancer is diagnosed but rather happens during childhood.
While the study shows a strong association between colibactin and colon cancer, it cannot prove that colibactin directly causes younger patients to develop cancer at an earlier age. However, researchers suggest that colibactin is just one of many factors contributing to the rise in colorectal cancer among young adults.
Environmental factors such as diet, sedentary lifestyle, medication, and others may be driving this increase in cancer cases. These factors can have downstream effects on the microbes in our gut, like E. coli, which may lead to increased risk of developing cancer.
The study’s findings are a new clue into the rise in colorectal cancer among young adults. Scientists believe that some confluence of environmental factors and their impact on the microbiome may be driving this steep rise.
While more research is needed, the study provides valuable insights into the relationship between colibactin and colon cancer. Future studies aim to investigate how different factors, including antibiotics use, nutrition, mode of birth, breastfeeding, and ultra-processed foods, may contribute to the development of this toxin.
Source: https://www.npr.org/sections/shots-health-news/2025/04/25/g-s1-62623/colon-cancer-gut-health-microbiome-young