Recurrence of tumor means that the tumor disappears after treatment for a period of time and grows back with the same nature. Metastasis of tumor refers to the process that tumor cells invade lymphatic vessels, blood vessels or body cavity from the original site and migrate to other places and continue to grow, forming the same type of tumor as the primary tumor, which is called metastasis. The spread of tumor refers to the tumor with infiltrative growth, which can not only continue to grow on the original site and spread directly to the surrounding tissues, but also spread to other parts of the body through various ways, which is the main characteristic of malignant tumor, and the spread mainly includes direct spread and metastasis.