Recurrence and metastasis are the main causes of cancer-related death and significantly decrease the survival rate of tumor patients. Cancer metastasis can initiate in the very early stage of malignant progression. Unfortunately, cancer patients may not necessarily feel or be diagnosed until metastatic clinical symptoms appear several months or years later.1 Metastatic cancer patients have lower five-year survival rates and the tumor often relapses.2 Cancer recurrence remains a major troublesome clinical problem which usually leads to treatment failure. Many cancer patients developed in situ recurrence or metastatic recurrence within five years after tumor resection.3 Accurate prediction of cancer recurrence and metastasis facilitates identifying high-risk patients and guiding appropriate treatment, offering the opportunity to prolong patients' survival.