The value of intratumoral microbiota in the diagnosis and prognosis of tumors

Intratumoral microbiota (ITM) are microorganisms present in tumor cells. ITM participate in tumor development by affecting tumor cells directly and the tumor microenvironment (TME), indirectly. Alterations in ITM instigate changes in tumor DNA, activate oncogenic pathways, induce tumor inflammatory responses, disrupt normal immune activity, and facilitate the secretion of effectors leading to tumor progression, metastasis, or diminished therapeutic effects. ITM varies significantly in different types of cancer cells and disease states. The presence of certain ITM serves as a predictor of various disease states. Thus, ITM predicts tumorigenesis, tumor grade, treatment efficacy, and prognosis, making it a potential tumor biomarker. The present study aimed to determine the mechanisms by which ITM affects tumor development, especially through the TME; highlight the significant potential of ITM in enhancing tumor diagnosis and prognosis; and outline future directions for ITM research, with a focus on the development of innovative tumor markers. In this review, we discuss that intratumor microbes (ITM) interact with the tumor microenvironment (TME) to influence tumor development. From there, bacteria are screened to become intratumor microbes while ITM remodel the TME to promote tumorigenesis. Second, we summarize the diagnostic prognostic potential of ITM in different tumor systems and the clinical potential of microbial diagnostics. In particular, we discuss the recent controversies regarding blood microbial DNA Blood microbial DNA.