Despite progresses achieved in the therapy of tumors,the prognosis of patients is still limited by reccurence of residual tumor cells.Cancer cell dormancy plays a pivotal role in cancer relapse and drug resistance.In recent years,tumor cells undergoing EMT(epithelial-mesenchymal transition),CSCs(cancer stem cells)and CTCs(circulating tumor cells)are proved to share some common characteristics and show a cell cycle arrest phenotype.Thus,understanding the dormant stage of tumor cells could facilitate us in discovering ways to accelerate the development of tumor therapy and prevent its reccurence.In this review,we summarize the specific process of tumor cell dormancy induced by pharmacotherapy,and consider that dormancy is an initiative response rather than a passive defense to cytotoxicity.Besides,we probe into the mechanisms of tumor cell dormancy-mediated drug resistance,anticipating paving a way to target dormant tumor cells and result in better clinical outcomes.