In recent years, doctors and researchers have observed a worrying increase in colorectal cancer in young adults, a disease previously more frequent in the elderly. From now on, this type of cancer threatens to become the main cause of mortality related to cancer in those under 50. A study recently published in Nature revealed that a bacterial toxin called Colibactin could be one of the possible causes of this trend.
A revealing genetic signature
Researchers have examined tumor samples from 981 patients with colorectal cancer, distributed in 11 countries. By studying the genetic changes associated with tumors, they found that, in more than half of the cases that occurred in young adults, the DNA alterations scheme corresponded to the typical effects of the Colibactin. This toxin is produced by certain strains ofThey exhibited chill (E. coli), bacteria naturally present in our intestine.
One of the authors of the study, the Biologist Ludmil Alexandrov of the University of California in San Diego, explains that the changes left by Colibactin act as a kind of historical archive in the genome, revealing that exposure to Colibactin during childhood could play a role in the early appearance of the disease.
Early exposure to suspected bacteria
The exact origin of this exhibition remains unclear, but the researchers believe that it would take place in the first ten years of life. One of the possible scenarios is that of infantile intestinal infections, during which strains ofE. coli produce Colibactin, which damages intestinal DNA. This altered DNA could then promote the development of cancers, well after the disappearance of toxin.
The data show that changes attributable to the Colibactin is 3.3 times more frequent in people diagnosed before 40 years than in those over 70 years. In older patients, genetic alterations seem more linked to natural aging.
-In other words, if a discharge of cancer is acquired very early in life, the development of the disease could be advanced for several decades. “” If a key transfer occurs before the age of 10, this can advance the development of colorectal cancer for several decades, making it appear around 40 years instead of 60 », Ajoute Alexandrov.
Other factors in question
Until now, the increase in colorectal cancers in young people has been largely attributed to factors linked to lifestyle, such as ultra-transformed food, excessive consumption of sugary or alcoholic drinks, sedentary lifestyle, etc. This new research suggests that elements related to the environment or lifestyle, from the first years of life, could also help lay the foundations for the disease.
However, other studies will be necessary to confirm these hypotheses. Unfortunately, recent budgetary reductions in the field of scientific research, especially in the United States, complicate the deepening of this work.
Researchers also want to explore to what extent it would be possible to protect organisms from the effects of Colibactin or to analyze the variations in risk factors between different countries. Researcher Marcos Díaz-Gay, from the Spanish National Center for Research on Cancer, stresses that the causes of the exposure to Colibactin could vary from one country to another. This could make it possible to develop prevention strategies adapted to each geographic area.
In addition, this alarming study shows that meat consumption increases the risk of colorectal cancer.
