This discovery will help in developing more effective ways to combat the spread of cancer metastases, according to the media department of the University of Lausanne in Switzerland.
Professor Tatiana Petrova of the University of Lausanne, whose statement was relayed by the university's press office, said: "We have shown that chemotherapy does not only affect the tumor itself. In particular, we were able to uncover a series of interactions between the intestine, bone marrow, and cancer metastases. It turns out that there are whole-body mechanisms that can be used to slow the growth of secondary malignant tumors."
Professor Petrova and her colleagues made this discovery while investigating the possible reasons why patients with aggressive forms of colorectal cancer have lower survival rates if they receive antibiotics before chemotherapy. This pattern has led biologists to believe that microbes somehow enhance the effect of drugs on cancer metastases.
Based on this idea, biologists injected mice with fluorouracil- and oxaliplatin-based chemotherapy, and a few days later implanted small pieces of rectal and colon tumors that had spread throughout their bodies. The researchers explained that this procedure helped them distinguish between the direct and indirect effects of the drugs on the tumors.
Specifically, studies by scientists have shown that the growth and spread of metastases in the liver and other organs of mice were significantly slowed because chemotherapy prompted gut microbiota cells to produce indole-3-propionic acid, a signaling substance that plays a crucial role in immune system function. Its molecules infiltrated the rodents' bone marrow and suppressed the formation of harmful immune cells that conceal tumors from the rest of the immune system and accelerate their growth.
This discovery prompted scientists to study the levels of indole-3-propionic acid molecules in the bodies of 14 patients undergoing treatment for colorectal cancer at Swiss clinics. Analysis by biologists showed that these patients' survival rates depended directly on the concentration of this byproduct of microbial activity, highlighting its crucial role in combating cancer metastases. Researchers hope that understanding this will lead to the development of new, highly effective treatments for metastatic tumors.
