evidence: When the first evidence of fungi coexisting with cancer was reported in 2019 in pancreatic cancer, it was suggested that cancer-associated fungi might impact the onset and progression of this cancer type. At the AACR Annual Meeting 2022, and in an article published this year, researchers showed that in a subset of pancreatic cancers, fungi promoted the secretion of an immune-suppressing protein called IL-33, potentially enabling these cancers to circumvent the antitumor effects of the immune response and progress to more advanced stages. Interestingly, the expression of IL-33 was increased by a mutated form of the KRAS protein, thus revealing a tumor-promoting collaboration between this common mutant and the mycobiome in pancreatic cancer. Building on these observations, the latest studies in Cell similarly identified correlations between fungi and cancer traits and outcomes. The presence of the Candida group of fungi, for example, was associated with inflammation and immune activation in stomach cancer, tumor-promoting gene expression changes in head-and-neck and colon cancers, metastasis in colon cancers, and reduced survival in various gastrointestinal cancers. Researchers found that interactions between fungi and surrounding bacterial communities correlated with outcomes, too. [...] While the relationship between the mycobiome and cancer is just beginning to be understood, it has become increasingly apparent that fungal species, like the bacteria and viruses studied before, could have a role in cancer, presenting new opportunities for treatment and disease monitoring.