The link is ‘intestinal microorganisms’
Chinese research team investigates intestinal microbial balance… When you are stressed, good lactic acid bacteria decrease.
Weakened immunity affects colon cancer growth
‘Lactobacillus’, a type of lactic acid bacteria… Increased ability to destroy tumor cells
“Effect of combined treatment with existing drugs”
For modern people, chronic stress is considered one of the causes of cancer and cerebrovascular disease. However, it has not yet been clearly established how stress in humans leads to fatal diseases such as cancer. Chinese scientists confirmed the effect of stress on colon cancer. Research results show that the link between stress and colon cancer is ‘intestinal microorganisms.’
Jinlin Yang, a professor in the Department of Gastroenterology and Liver Diseases at Sichuan University in China, investigated the impact of chronic stress on the progression of colorectal cancer and confirmed that intestinal bacteria are the link between the two. The research results were presented at the 2024 Conference held in Vienna, Austria on the 13th. It was presented at the ‘European Society of Gastroenterology Week’.
Analysis suggests that chronic stress can accelerate the progression of colon cancer by disrupting the balance of intestinal microorganisms. It is expected to provide clues to opening new paths for the prevention and treatment of colon cancer, one of the cancers that frequently occur in modern people.
●Stress, weakening immune response by reducing beneficial bacteria in the intestines
Colon cancer is one of the cancer types with a high mortality rate. According to Statistics Korea’s 2023 cancer death data, colorectal cancer is the cancer with the third highest mortality rate after lung cancer and liver cancer. The incidence of colon cancer is expected to increase further in the future due to aging, eating habits, lack of physical activity, and obesity.
To prevent colon cancer or prevent it from getting worse, you must reduce total calorie intake, consume enough fiber, and improve bad habits such as smoking and drinking. The research team also confirmed that stress management and intestinal microbial balance are important.
The research team first applied cocktail therapy of antibiotics such as vancomycin, ampicillin, neomycin, and metronidazole to a mouse model of colon cancer to eradicate intestinal microorganisms. Antibiotics are substances that inhibit the growth of microorganisms, and cocktail therapy refers to the combined use of three or more drugs.
Then, the research team performed fecal transplantation (FMT) on mice with colon cancer. FMT is a procedure in which beneficial bacteria are purified from the stool of a healthy individual and then injected into the transplant recipient. Through this, while the colon cancer mice had a healthy intestinal microbial environment, the research team applied chronic stress.
As a result, chronic stress not only affected the growth of colon cancer, but also reduced beneficial intestinal bacteria, which are essential for improving the immune response to cancer cells. In particular, Lactobacillus, a type of lactic acid bacteria, decreased.
The research team explained, “The progression of colon cancer in mice under chronic stress may be due to a decrease in beneficial intestinal bacteria,” adding, “When beneficial bacteria decrease, the body’s immune response to cancer is weakened and cancer progresses.”
The research team administered Lactobacillus to mice while they were stressed to see how Lactobacillus affected the levels of cytotoxic T cells (CD8+ T), which play an important role in the body’s anti-tumor immunity, and the progression of colon cancer. Cytotoxic T cells are a type of lymphocyte that can destroy tumor cells.
Analysis of mouse stool showed that Lactobacillus regulated bile acid metabolism and improved the function of cytotoxic T cells. Bile acids are known to interact with microorganisms, change the composition of intestinal microorganisms, and affect the occurrence and progression of cancer. The research team interpreted that “Lactobacillus can reduce the risk of tumor formation in mice under stress.”
●Lactobacillus emerges as a key to treating colon cancer
Previously, a domestic research team also published a paper confirming the relationship between beneficial intestinal bacteria and the development of colon cancer. According to a research paper published by the gastroenterology research team at Seoul National University Bundang Hospital in the international journal ‘Intestines and Liver’ in January, there were significantly more beneficial bacteria, such as lactic acid bacteria and butyric acid bacteria, in the intestines of healthy control groups than those of colon cancer patients.
The relationship between harmful bacteria and colon cancer was also confirmed. According to a paper by a research team from the University of Bristol, UK, presented at the 2019 National Cancer Institute conference, the risk of colon cancer increases by 2 to 15% if there are many Bacteroidales bacteria in the intestines.
This study from Sichuan University confirmed the potential of Lactobacillus-based therapy in treating colorectal cancer patients affected by chronic stress. The research team explains that combining existing anti-tumor drugs with Lactobacillus supplements could be effective in treating colon cancer caused by chronic stress.
The research team added, “We discovered that certain microorganisms could be potential targets for treatment,” adding, “Restoring beneficial intestinal bacteria such as lactic acid bacteria could strengthen the body’s natural defense ability against colon cancer.”