Circulating tumor cells (CTC) detection, due to its good sensitivity and specificity, less trauma, convenience and repeatability of obtaining materials, has gained clinical consensus for its advantages in early diagnosis, clinical staging, guiding treatment and predicting prognosis. However, it still remains unclear that the significance of CTC as an indicator for maintenance therapy. In this paper, we reviewed the extraction, isolation, detection and clinical application of CTC, and its value in maintenance therapy.