A recent article in the New York Times highlights the discovery of the presence of distinct sets of fungi, in addition to bacteria, in different tumor tissues across body sites. Scientists have been long aware that our bodies host microbes but had the preconception that tumors did not harbor microbes, along with many other organs that were thought to be sterile. However, recent work has shown that these supposedly sterile organs contain their own unique microbes. Taking a closer look at the tumors showed that they may contain many distinct bacterial species. In 2020, a research group documented the presence of different bacterial compositions in tumors.
Two studies on tumor microbiota published last September found that the tumor microbiome contains a range of bacteria and fungi that are unique to tumors from different body sites. The researchers hypothesized that these unique compositions could be used as early markers of hidden tumors, and that these could be identified from microbial DNA shed into the host blood. The researchers identified fungi in tumor samples from 35 different cancer types in the mouth, esophagus, stomach, colon, rectum, breast and lungs. All the types of tumors harbored their own unique fungal composition. Dr. Saxena, a microbial ecologist at NYU, noted that the amount of fungus identified in tumors was unexpected, and could change our understanding of tumors. The vast web of fungi-bacteria-immunity ecologies in tumors is a new and novel field of study. Despite the novelty of the field, new studies are finding microbes that may play roles in cancer outcomes. For example, Dr. Iliev and his colleagues identified a fungus called Candida tropicalis in tumors of patients who died due to stomach cancer. There may be a causal relationship between cancer outcome and microbial residents of tumors, as bacteria may evade tumors from the immune system or neutralize drugs. According to Dr. Galloway-Peña from Texas A&M University, we still do not know if resident microbes of tumors do have a causal impact on cancer outcomes. To read more please visit the original article.