Figure 1

Mechanisms in tumor dormancy. Tumor dormancy can lead to tumor recurrence locally or to metastasis at a distant site. Dormancy can be induced by more than one mechanism: cellular dormancy (quiescence), angiogenic dormancy (tumor mass size limit), and immunologic dormancy (immunosurveillance, balance between proliferation and apoptosis). Others mechanisms, such as epigenetic change, tumor microenvironment, CSCs, EMT, and miRNA, also may involve in tumor dormancy. A tumor microenvironment that is altered (such as by frontline treatment) can mediate tumor cell entrance into, maintenance, and exit from dormancy through interaction with cells at niches, such as endothelial cells, stroma, or immune cells.