The gastrointestinal tract contains a vast and diverse microbial reservoir composed of bacteria, fungi, and viruses that contribute positively to human health. There is growing evidence that perturbation of the normal microbiota can promote a variety of human disease states that include tumorigenesis. Whether the fungal component of the gut microbiota (i.e., the mycobiota) can influence tumor development has not been investigated in detail. In the recent issue of the Theranostics, Zhong et al (2021) shed light on an association between mycobiota dysbiosis and gastric cancer. These findings implicate the mycobiota in gastric carcinogenesis and set the stage for future mechanistic studies to explore whether fungal dysbiosis is a cause or consequence of gastric carcinogenesis, with important implications for preventative strategies.