Radical radiotherapy and postoperative radiotherapy may completely kill tumor cells, while preoperative radiotherapy and palliative radiotherapy cannot completely eliminate tumor cells. 1. Radical radiotherapy: for early stage tumors that are more sensitive to radiotherapy, tumor cells can be completely killed by radical radiotherapy. 2. Preoperative radiotherapy: for tumors with large size and high difficulty in surgery, preoperative radiotherapy can be used to reduce the size of the tumor and lower the difficulty in surgery, and then the tumor can be removed through surgery. 3. Postoperative radiotherapy: patients with tumors with high risk factors need to cooperate with radiotherapy after surgery to kill the tumor cells that have not been completely removed, so as to reduce the probability of recurrence and metastasis. 4. Palliative radiotherapy: For advanced malignant tumors, palliative radiotherapy can improve patients’ survival treatment and prolong the survival period, but it cannot make the tumor disappear. Tumor patients should be treated as early as possible, strive for radical surgical resection or radical radiotherapy, and after treatment, regular review is needed to prevent tumor recurrence or metastasis.