Dormant mechanisms reveal the clinical significance of tumor dormancy: A narrative review

Abstract

After successful treatment, there is still the possibility of recurrence and metastasis in patients with malignant tumor. The reason why malignant tumor can recur after years and even decades of successful treatment is attributed to a small amount of dormant tumor cells remained in host for years. The dormancy state is unstable and may re-enter the proliferating state under appropriate conditions, leading to tumor recurrence and metastasis. Compared with the primary tumors, recurrent tumors or metastatic tumors are insensitive to conventional radiotherapy and chemotherapy. This characteristic of malignant tumor has become the difficulty of treatment, and it is also the cause of death of most tumor patients. Tumor dormancy puts forward challenges for clinical control and opportunities for scientific discovery. With its current pictures of the mechanisms of tumor dormancy and reawakening remaining incomplete, it is unclear when and which dormant cells will resume proliferation causing late relapse, and which will remain asymptomatic and harmless to their hosts. Here, we will discuss the regulation of autophagy, angiogenesis and immunity on tumor dormancy, and briefly introduce the clinical implications of tumor dormancy from the perspective of the above mechanisms. With better understanding of tumor dormancy at the molecular level, novel cancer therapeutics could be provided, turning into effective treatments for cancer patients.