What is the gut microbiota? Why is it important in cancer care? The gut microbiota is the name of the bacteria that live in the digestive and intestinal tract. Recent studies have shown that a healthy gut microbiota, filled with healthy bacteria, may protect some people from developing certain cancers as well as metastasis. The medical theory that probiotics (probiotics grows bacteria, the opposite of antibiotics, which kills bacteria) promotes “good” bacterial growth and supports our immune system is widely accepted. However, how probiotics may strengthen the immune system to fight cancer is a subject of intense interest and controversy in the medical and cancer communities.
Let’s examine some of the most recent research.
Targeting and supporting the immune system in pancreatic cancer patients
A December 2019 study in the scientific journal Molecular Cancer (1) touches on evidence that “occurrence, development and therapy of Pancreatic Cancer are all related to the microbiome in vivo. The study of microbes in the pancreatic tumor microenvironment may also have potential significance for treatment of pancreatic cancer. The use of probiotics/antibiotics may be combined with traditional treatments such as surgery, radiotherapy and chemotherapy, as well as emerging targeted therapies and immunotherapies, to yield novel treatment options.”
In this research, probiotics and antibiotics are suggested as a treatment to help fortify the immune system by ridding the pancreas microenvironment of harmful bacteria. A 2018 study from New York University School of Medicine (2) found harmful bacteria can quickly multiply (at a 1000 fold increase) in pancreatic cancer patients and completely overwhelm the patient’s immune system and its ability to attack tumor cells.
A January 2021 study (3) also suggested the newly discovered importance of microorganisms in Pancreatic cancer.
In this study researchers tell of the difficulty in early diagnosis of pancreatic cancer “owing to the lack of specific symptoms and reliable biomarkers. The cause of pancreatic cancer remains ambiguous. Smoking, drinking, new-onset diabetes, and chronic pancreatitis have been proven to be associated with the occurrence of pancreatic cancer. In recent years, a large number of studies have clarified that a variety of microorganisms colonized in pancreatic cancer tissues are also closely related to the occurrence and development of pancreatic cancer, and the specific mechanisms include inflammatory induction, immune regulation, metabolism, and microenvironment changes caused by microorganism.” (The development of pancreatic cancer my have something to do with immune disorders, inflammation, and thriving populations of harmful microorganisms).
The mechanism of action of the pancreatic colonized microbiome in the tumor microenvironment, as well as immunotherapy approaches require further study in order to find more evidence to explain the complex relationship between the pancreatic colonized microbiome and Pancreatic ductal adenocarcinoma. Relevant studies targeting the microbiome may provide insight into the mechanisms of Pancreatic ductal adenocarcinoma development and progression, improving treatment effectiveness and overall patient prognosis.”
Not just the pancreases, its the colon too. Targeting and supporting the immune system in colorectal cancer patients
A November 2019 study examined and implicated unchecked bad bacteria in the gut in the development of colorectal cancer. The research in the World Journal of Clinical Cases (4) says: “Several etiologic factors trigger colorectal cancer; however, the gut microbiome is responsible of most of the cases. Gut bacteria can produce a variety of chemical compounds that affect intestinal cells and might transform them into malignant ones. . . A plethora of research has suggested that an imbalance in normal intestinal microbiota can trigger inflammatory conditions by producing carcinogenic metabolites that lead to cancer formation, and about 16% of human cancers are triggered by bacteria.” By keeping these bacteria in check “we would,” the researchers concluded, “be able to avoid at least life-threatening diseases such as colorectal cancer.”
Bad bacteria leads to metastasis through inflammation
An October 2019 (5) study shows how bad bacteria in the gut microbiota controls and nurtures cancer growth. This research was published in the Journal of Oncology.
“(pathogenic microorganisms or bad bacteria leads to) biological alterations and pathways modulated by a dysbiotic (a harmful imbalance) microbiota and potentially (are) involved in the control of cancer progression.”
The molecular mechanisms most frequently affected by the pathogenic microorganisms to induce malignant progression involve epithelial-mesenchymal transition-dependent barrier alterations (this alteration allows cancer cells to slip through the immune system and move to other organs where they metastasize). This process alteration is aided by tumor-promoting inflammation.
Simply stated, the bad bacteria opens holes for cancer cells to pass through cell linings and invade other organs. These cancer cells are supported on their journey by cancer protective inflammation. Stop the bad bacteria from creating the holes and inflammation, stop the cancer spread.
Can the microbiota can be manipulated to help improve cancer treatment and prevent cancer spread?
A 2017 study from the University of North Carolina (6) suggests that probiotics can manipulate the microbiota to suppress cancer spread and kill cancer cells. This is what the researchers wrote:
“(the) microbiota can alter cancer susceptibility and progression by diverse mechanisms, such as modulating inflammation, inducing DNA damage (this would damage cancer’s ability to mutate) and producing metabolites (amino acids) involved in oncogenesis or tumor suppression.
Evidence is emerging that microbiota can be manipulated for improving cancer treatment. By incorporating probiotics as adjuvants for checkpoint immunotherapy or by designing small molecules that target microbial enzymes, microbiota can be harnessed to improve cancer care.”
Probiotic Bacteria and Probiotic Yeast
Research has shown that a yeast, Saccharomyces cerevisiae (Baker’s yeast), found in certain over-the-counter probiotic formulations could address many toxic elements of chemotherapy including diarrhea. It is estimated that 50-80% of patients undergoing chemotherapy will develop diarrhea as a side-effect of the treatment. Diarrhea can be dangerous for some as it will lead to dehydration and nutritional absorption problems. While being an anti-diarrheal treatment is an extremely important function, this probiotic yeast is speculated to be able to do much more.
Doctors writing in the medical journal Critical Reviews in Microbiology (7) comment:
There is a common agreement about the role of colonic microbiota in the etiology of different cancers. Probiotics have been examined for their anti-cancer effects, and different mechanisms have been suggested about their antitumor functions. Non-pathogenic yeasts, as members of probiotics family, can be effective on gut microbiota dysbiosis (the gut imbalance and loss of harmony).
Probiotic yeasts influence physiology, metabolism, and immune homeostasis in the colon and contribute to cancer treatment due to possessing anti-inflammatory, anti-proliferative and anti-cancer properties.
In this study, doctors focused on the possible cellular and molecular mechanisms of probiotic yeasts such as inactivation of carcinogenic compounds, especially those derived from food, improvement of intestinal barrier function, modulation of immune responses, antitoxic function, and anti-proliferative effects.