Emerging roles of intratumor microbiota in cancer metastasis

Cancer metastasis is the leading cause of mortality in patients with cancer. Theories have been developed to explain the causes and principles of metastasis. Metastasis is attributed to cancer cell-intrinsic properties and the extrinsic cellular environment. In recent years, the intratumor microbiota has been identified as an integral tumor component and may functionally regulate various aspects of metastasis. These novel discoveries in intratumor microbiota reshape the framework of our understanding of metastasis and reveal a new path for studies on cancer progression and clinical cancer management. Here, we summarize recent advances in the emerging roles of intratumor microbiota in cancer metastasis and discuss the challenges and implications for cancer treatment.