An international team of scientists has created the first pan-cancer mycobiome atlas that reveals of mycobiomes in 35 cancer types. This study provides a comprehensive characterization of the cancer mycobiome in tissues and blood, compares fungal communities with corresponding bacteriomes and immunomes, and explores fungal utility for prognosis and diagnosis.
Mycobiome is a term that combines two words: mycology and microbiome. The first refers to the study of fungi and the second refers to the microorganisms that live together in an environment. Mycobiome is a variety of fungal species that reside within a particular body space.
Fungi are important commensal/opportunistic pathogens that shape host immunity and infect immunocompromised patients, including cancer patients. The associations of fungi with clinical parameters including progression-free survival in ovarian cancer, immunotherapy response in melanoma tumors, and detection of early-stage cancers support their clinical utility as potential biomarkers and therapeutic targets.
About the study
The research team has created the first atlas of pan-cancer mycobiome, a survey of 35 types of cancer and their associated fungi. It characterizes the mycobiomes of 17,401 tissue and blood samples in four independent cohorts of 35 cancer types.
The fungi were detected in all cancer types examined, but, all individual tumors were not positive for the fungal signal. The imaging showed that most fungi were intracellular in cancer and immune cells, analogous to intratumoral bacteria. The causal relationship or association of these fungi remains to be determined.
The results also showed cancer-type-specific fungal ecologies with less diversity and abundance than the corresponding bacteriomes. Specific fungi significantly correlated with age, tumor subtypes, smoking status, immunotherapy response, and survival measures.
To investigate the potential effects of fungi in tumors, the researchers explored mycobiome-bacteriome-immunome interactions. A comparison of intratumoral fungal communities with corresponding bacteriomes and immunomes showed co-occurring bi-domain ecologies, often with permissive, rather than competitive, microenvironments and distinct immune responses. These findings showed strong positive correlations between fungal and bacterial diversity, abundance, and co-occurrence in several types of cancer.
Researchers speculated that tumor microenvironments can be non-competitive spaces for multidomain microbial colonization. This differs from an ”antagonistic” phenotype observed in the gut, especially under anticancer or antibiotic therapies, where fungal and bacterial populations alternate and compete over shared resources. Clinically focused evaluations have found prognostic and diagnostic capacities for the tissue and plasma mycobiome, even in stage I cancers.
The authors concluded that their study broadens the cancer microbiome landscape, but does not establish causality. This first pan-cancer mycobiome atlas characterized a new layer of information for cancer diagnostics and therapeutics.
The study was published in the scientific journal Cell. Narunsky-Haziza L. Et al. Pan-cancer analyses reveal cancer-type-specific fungal ecologies and bacteriome interactions. Cell 2022, 185, 3789–3806. (Open Access) https://www.cell.com/cell/fulltext/S0092-8674(22)01127-8