Thus, chronic stress accelerates the progression of colorectal cancer.

All indications are that colorectal cancer will once again become the most common cancer in Spain this year, with 44,294 new cases recorded, followed by breast, lung and prostate cancer.

Causes include excess weight, type 2 diabetes, smoking and genetic factors. But the true reason is not always known.

To delve deeper into this topic, a team of researchers found that chronic stress accelerates the progression of colorectal cancer by altering the balance of the gut microbiota.

“In our rodent study, we used a cocktail of antibiotics (vancomycin, ampicillin, neomycin, and metronidazole) to eradicate gut microbiota, followed by fecal microbiota transplantation to examine whether gut microbiota is required to accelerate chronic stress. progression of colorectal cancer,” explains Dr. Qing Li, principal investigator of the study presented at UEG, European Gastroenterology Week, in a statement.

The results showed that chronic stress not only increases tumor growth, but also reduces the number of beneficial gut bacteria, especially the genus lactobacilliwhich are essential for a healthy immune response against cancer.

“Stress-related progression of colorectal cancer may be explained by to a decrease in the number of beneficial intestinal bacteriabecause it’s weakens the body’s immune response against cancer”says Lee.

“Lactobacilli sensitive to vancomycin and ampicillin was reduced in both the control and stress groups when given a cocktail of antibiotics. “This reduction highlights its critical role in maintaining gut health and its possible link to colorectal cancer progression under chronic stress,” he says.

To further study how lactobacilli affect levels of CD8+ T cells (which play a critical role in the body’s antitumor immunity) and the progression of these cancers, the researchers supplemented mice with lactobacilli during chronic stress and observed a reduction in tumor formation.

“Through stool analysis, we found that Lactobacillus plantar (L. plantarum) specifically regulates bile acid metabolism and improves CD8+ T cell function. “This indicates how lactobacilli may improve antitumor immunity,” says the researcher.

This specialist explains that during the investigation, unexpected conclusions were also revealed. “We initially thought that L. plantarum might enhance the antitumor immune function of CD8+ T cells by initiating the production of metabolites, as shown by the above results. However, our in vitro tests showed that it does not significantly stimulate CD8+ T cells to produce these key metabolites. “This indicates that L. plantarum may require substances in the intestinal environment to enhance the antitumor function of CD8+ T cells.”

The potential for lactobacilli-based therapies to treat patients, especially those suffering from chronic stress, is promising. “Combining traditional anticancer drugs with L. plantarum supplementation may be a viable therapeutic strategy for patients with stress-induced CRC,” admits Lee.

Colorectal cancer is a major health problem throughout Europe, the second most common type of cancer and the second leading cause of cancer mortality. Its incidence is expected to increase significantly in the next decade due to an aging population, unhealthy diets, physical inactivity and obesity.

In the future, the research team plans to collect fecal and tumor samples from colorectal cancer patients to analyze changes in the gut microbiota in people with and without chronic stress. “We aim to test whether L. plantarum levels are significantly reduced in colorectal cancer patients under stress and explore its association with anti-tumor immune cells,” Li shared.

This study highlights the complex relationship between stress, gut microbiota, and colorectal cancer, suggesting that strategies to restore gut health may play a critical role in cancer treatment, especially for patients suffering from chronic stress. “Restoring beneficial bacteria in the gut, such as lactobacilli, may strengthen the body’s natural defenses against colorectal cancer,” Lee concluded.