Is the cure for cancer in the intestine?
Does the cure for cancer lie in the gut?
David Cox, The Telegraph
Translation: InoSMI
Can fecal microbiota transplantation save your life? This is a new branch of research that an increasing number of oncologists around the world are paying attention to. Scientists are trying to find new ways to use the intestinal microflora – the many different microorganisms living in your gut – to treat deadly diseases.
In February, scientists from King's College London published a large-scale study that showed that patients with melanoma responded much better to immunotherapy if certain beneficial bacteria were present in their intestinal microflora.
This turned out to be an extremely important discovery, because oncologists have long been looking for ways to improve the effectiveness of the treatment of melanoma, an aggressive type of cancer that can lead to death if it spreads to other organs. Although various types of immunotherapy – such as immune response checkpoint inhibitors – can stop the development of melanoma, they help only 50% of patients.
The intestine has long been considered just a part of the digestive system, but in recent years scientists have begun to realize that it plays a crucial role in maintaining and strengthening our immune system. About 100 thousand billion bacteria, viruses and fungi live in our intestines, which we receive at the very beginning of life. The composition of the intestinal microflora gradually changes throughout our lives, and it depends on our diet, as well as on factors such as taking antibiotics, sleep quality and stress levels.
Although scientists are still studying the nature of interactions between all these microbes, it has already been proven that certain types of bacteria, such as Bifidobacterium pseudocatenulatum and Akkermansia muciniphila, have a positive effect on the immune system.
According to Megan Rossi, who is engaged in research in the field of intestinal health at King's College London, the intestinal microbiota contains a huge potential in the sense of cancer treatment.
"We know that about 70% of the immune system is contained in our intestines," she said. – Microbes living in the intestine play a very important role in regulating the immune system, and the results of many studies confirm this. It seems that soon we will be able to predict who will respond better to the treatment of certain diseases, based on data on the composition of the intestinal microflora in these people."
Some scientists have already taken the first steps towards understanding whether we can increase the chances of successful treatment by directly changing the composition of the intestinal microflora in patients with cancer. Although in this case, supplements with probiotics are unlikely to help significantly – Rossi called them just a "drop in the bucket" – some scientists have already managed to achieve some success using the method of fecal microbiota transplantation.
As part of this method, a stool sample of a healthy person is taken, and this material is transplanted directly into the intestines of cancer patients through colonoscopy. The advantage of this method is that it allows you to transfer the entire colony of microorganisms and their synergistic interactions at one time.
Last year, experts at the National Cancer Institute in the United States conducted a pilot study in which they examined stool samples taken from melanoma patients who responded well to immunotherapy and transplanted them to those melanoma patients who did not respond to therapy. Six of their 15 patients who did not respond to therapy showed positive dynamics after intestinal microbiota transplantation.
"It didn't work for everyone. However, now scientists are conducting additional research, trying to figure out why some patients started responding to therapy, and others did not," Rossi said.
The interest in fecal microbiota transplantation is so high that, according to Rossi, her colleagues at King's College in London are currently working to identify "super-donors" – people with the most optimal composition of intestinal microflora, which can be further used to treat people suffering from chronic diseases. "They check healthy patients, including for the presence of a number of viral diseases, analyze their anamnesis, as well as their diet, how patients sleep and cope with stress," she said.
She warned that in the world of oncology, these studies are still in their initial phase – this method is now much more actively used to treat other diseases, such as irritable bowel syndrome, and a lot of work needs to be done. However, Rossi notes that in the future, to improve the effectiveness of cancer treatment, instead of microbiota transplantation, it will be possible to use special tablets containing samples of the intestinal microflora of super-donors.
In the coming years, we may even be able to fight specific carcinogenic bacteria by removing them from the intestinal microflora of cancer patients in order to prevent the progression of cancer. Sequencing studies have identified a class of bacteria called Fusobacterium, which are present in large numbers in the tissues of the affected bowel cancer, and demonstrated that these bacteria contribute to the growth of tumors and the development of resistance to chemotherapy.
"This is another area of research," Rossi said. "Scientists are exploring ways to use phage therapy–when viruses suppress certain types of bacteria–to rid patients of bacteria that contribute to the development of cancer."
But in the near future, according to Rossi, most likely, we will see how cancer patients will begin to be divided into groups based on the composition of their intestinal microflora. "Some patients may be offered certain medications because certain bacteria are present in their intestines," she explained.
The intestinal microbiota can also be a valuable source of information for detecting cancer at the earliest stage of its development. Scientists will be able to find certain signatures of certain microorganisms and their metabolites – chemicals secreted by these bacteria – in order to detect various types of cancer.
Last week, scientists from the Spanish National Cancer Research Center published the results of a study in which they were able to determine the ratio of bacteria, fungi and viruses associated with pancreatic cancer. This is a particularly important finding because pancreatic cancer is often not diagnosed at an early stage, when it responds better to treatment because patients have no symptoms.
"Microbiota signature research has huge potential, because if we talk about cancer, the sooner you find it, the more successful its treatment will be," said Stephen Robinson, a specialist in cancer at the University of East Anglia.
Robinson is currently working with experts from the Quadram Institute and Norfolk and Norwich University Hospital to find out if it is possible to determine the signature of the intestinal microbiota for breast cancer patients.
However, he warns that it will take at least ten years before scientists can say with certainty that they have accurately determined the composition of the intestinal flora, indicating the onset of cancer. "This requires long–term research," he explained. "It is necessary to gather a large group of women, who will then need to be monitored for several years to find out if there is a signature associated with the development of breast cancer."
This project has a less long-term task, which in turn can help in the treatment of those who suffer from breast cancer right now. Robinson is particularly interested in observing the effects of various cancer therapies on patients' microbiota, and he wants to find out if there are ways to improve the effectiveness of therapy.
"We want to start observing these women from the very beginning, even before they start therapy, and then check whether transplanting specific components of the microbiota can benefit them, make them respond better to chemotherapy or radiotherapy," he explained. "I believe that in this area our research can lead to visible results faster."
Since there is now more and more evidence that the health of our intestines has a significant impact on our resistance to various diseases, what can we do to improve the state of our intestinal microflora?
According to Rossi, the answer is simple. Make sure that your sleep is complete, and there are as many vegetable products on your table as possible.
"It is extremely important to sleep from seven to nine hours a day. And it's very important to eat as many different vegetables as possible, which will help you nourish certain types of microorganisms in your intestines," she explained. – It seems to me that many people in the UK rarely follow these simple rules. We often eat the same thing. But there are six large categories of plant foods–whole grains, nuts, fruits, vegetables, seeds and spices."
"People who eat foods from all six categories have healthier intestines compared to those who constantly eat the same foods. The next time you eat a salad, add legumes, grains and seeds to increase the diversity of your gut flora."
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