How does the microbiome affect cancer?
Cancer is one of the leading causes of mortality; almost one in six deaths worldwide is due to cancer (1). Among several treatment options, chemotherapy and immunotherapy are used to treat cancer by preventing the cancer cells from dividing or by strengthening the immune system to eliminate the cancer cells (2). Despite advances, treatment results for most types of cancer are still unsatisfactory.
The intestinal microbiome, i.e. the entirety of microorganisms that live in the intestine, is increasingly coming to the fore in cancer research. It is considered an important factor that is associated with both tumor development and the effectiveness of cancer therapies (3). Understanding how microorganisms affect cancer could open up new avenues for cancer prevention, treatment, and management (8,9).
How does the intestinal microbiome affect our health?
The human body is a complex ecosystem inhabited and influenced by a plethora of microorganisms, including bacteria, yeast, fungi and viruses, which together make up the microbiome. On average, a healthy human body consists of about 30 trillion cells and is inhabited by about 39 trillion bacterial cells (4). The microbiome influences a variety of metabolic processes, including the production of hormones, essential vitamins, and other bioactive compounds that cannot be acquired by humans through other means (5). Also on that immune system and Nervous system the microbiome has a direct influence (6).
Microbiome and the connection to cancer
Changes in the microbiome can contribute to the development of various diseases. In the context of cancer, some specific bacteria have been proven to be involved in the process of tumor development. In doing so, some of these bacteria activate inflammatory reactions and disrupt the mucous layers that protect the body from outside invaders. This creates an environment that promotes tumor growth. In other cases, bacteria also promote cancer survival by making cells resistant to anticancer drugs (7).
However, intestinal bacteria can also help fight tumors (12). In 2013, a study at the National Cancer Institute in Bethesda, Maryland, showed that some cancer treatments rely on the gut microbiome activating the immune system. The chemotherapy drug cyclophosphamide has been found to damage the mucus layer that lines the intestines, allowing some intestinal bacteria to migrate to the lymph nodes and spleen, where they activate specific immune cells. In mice raised without microbes in the gut or treated with antibiotics, the drug largely lost its anticancer effects (13, 14).
The gut microbiome has the potential to influence the effectiveness of cancer therapy
In another study, stool samples from several cancer patients who were treated with chemotherapy or a combination of chemotherapy and immunotherapy were analyzed. It was found that the intestinal microbiome of those cancer patients who responded well to therapy had a higher microbial diversity (10). Diversity describes the diversity of the microbiome and also shows whether the different types of bacteria occur evenly in the intestine or whether some types of bacteria dominate. The more different types of bacteria occur evenly in the intestine, the higher the diversity and the more resilient the microbiome is (11).
The relationship between the microorganisms living in the intestine and humans is complex. Each individual has inherited a specific microbiome footprint since birth. With the As we age , diet and lifestyle, the microbiome continually develops and changes. If we take a preventive approach to our microbiome health and positively influence the microbiome with the right diet and lifestyle, we are taking an important step towards a healthy life.
In order to preventively control and support your microbiome, myBioma gives you the opportunity to test your intestinal health from the comfort of your own home. Learn more!
References
- World Health Organization. 2018. https://www.who.int/health-topics/cancer. Accessed 2019.
- Emens LA, Middleton G. The interplay of immunotherapy and chemotherapy: harnessing potential synergies. Cancer Immunol Res. 2015;3:436–43.
- Zitvogel L, Ma Y, Raoult D, Kroemer G, Gajewski TF. The microbiome in cancer immunotherapy: diagnostic tools and therapeutic strategies. Science. 2018;359:1366–70.
- Sender R, Fuchs S, Milo R. Revised estimates for the number of human and Bacteria cells in the body. PLoS Biol. 2016;14(8):e1002533.
- Lepage P, Leclerc MC, Joossens M, Mondot S, Blottière HM, Raes J, et al. A metagenomic insight into our gut’s microbiome. Gut. 2013;62(1):146–58.
- Vernocchi P, Del Chierico F, Putignani L. Gut microbiota profiling: metabolomics based approach to unravel compounds affecting human health. Front Microbiol. 2016;7:1144.
- Zhang H, Sun L. When human cells meet bacteria: precision medicine for cancers using the microbiota. Am J Cancer Res. 2018;8(7):1157–75.
- Sivan A, Corrales L, Hubert N, Williams JB, Aquino-Michaels K, Earley ZM, et al. Commensal Bifidobacterium promotes antitumor immunity and facilitates anti-PD-L1 efficacy. Science. 2015 Nov 27;350(6264):1084–9.
- Vétizou M, Pitt JM, Daillère R, Lepage P, Waldschmitt N, Flament C, et al. Anticancer immunotherapy by CTLA-4 blockade relies on the gut microbiota. Science. 2015 Nov 27;350(6264):1079–84.
- Heshiki Y, Vazquez-Uribe R, Li J, Ni Y, Quainoo S, Imamovic L, Li J, Sørensen M, Chow BKC, Weiss GJ, Xu A, Sommer MOA, Panagiotou G (2020) Predictable modulation of cancer treatment outcomes by the gut microbiota. Microbiome 8(1):28. doi: 10.1186/s40168-020-00811-2.
- Lozupone CA, et al. Diversity, stability and resilience of the human gut microbiota. Nature 489, 220 (2012).
- https://www.nature.com/news/gut-microbes-can-shape-responses-to-cancer-immunotherapy-1.22938
- https://science.sciencemag.org/content/342/6161/971
- https://science.sciencemag.org/content/342/6161/967
