Medical Oncology is a relatively new discipline developed in the treatment of tumors, although it has a short history, it is developing rapidly. As the name implies, medical oncology refers to the drug treatment of tumors. In the early days, chemotherapy drugs were mainly used, so it was also called chemotherapy, and hospitals called the department of drug treatment for tumor patients as chemotherapy department, and now many general hospitals still call it chemotherapy department. With the development of tumor research and the emergence of new drugs, the drugs for tumor treatment are not only chemical drugs, but also biological agents and targeted drugs, which make the drug treatment of tumor cover more extensive. The most important feature of medical therapy is that it can control or eliminate the distant metastasis which is the most threatening to tumor patients, so it occupies an important position in the comprehensive treatment. The indications of medical oncology treatment: Medical oncology treatment started from palliative treatment, which was mainly used to treat advanced disseminated tumors that could not be operated or treated with radiotherapy in the beginning, and later on, with the development and maturity of internal medicine, it showed more and more active role and potential ability in the radical treatment of tumors, and the number of tumors cured by medical oncology treatment or participation in treatment gradually increased. At present, medical oncology treatment is mainly applied to the following aspects: 1. Hematological system tumors: such as leukemia, lymphoma, multiple myeloma, etc. These tumors have the characteristics of systemic spread and are more sensitive to chemotherapy, so they are often preferred to medical treatment. 2. Post-operative adjuvant therapy: such as osteosarcoma, breast cancer, gastrointestinal tumor, lung cancer, ovarian cancer, etc. After surgical resection of these tumors, in order to prevent recurrence and metastasis, treatment is provided for possible micro-metastases. Adjuvant treatment can often improve the cure rate and reduce tumor recurrence. 3.Treatment of advanced tumors: such as lung cancer, gastrointestinal tumors, breast cancer, pancreatic cancer, bone sarcoma, gynecological tumors, kidney cancer, soft tissue tumors and so on. Many tumors are late when they are found, and some tumors have distant metastases after preliminary treatment. Most patients in this category can be treated with drugs to reduce pain and prolong survival to a certain extent. 4.Treatment of cancerous effusion: such as cancerous thoracic, abdominal and pericardial effusion. When the above effusion appears in advanced tumor, it can often be controlled to different degrees and alleviate the patient’s symptoms through intracavitary injection of tumor treatment drugs after draining the effusion. 5.Pre-operative adjuvant therapy: such as lung cancer, breast cancer, gastrointestinal tumor, bone sarcoma, etc. Recent studies have found that for certain stages of tumors, preoperative drug therapy can improve the surgical resection rate and cure rate. This treatment is often called neoadjuvant therapy. 6.Tumor emergencies: For certain chemotherapy-sensitive tumor patients with superior vena cava syndrome, elevated intracranial pressure caused by brain metastasis, spinal cord compression, etc., the preferred chemotherapy can reduce the symptoms as soon as possible and create conditions for radiotherapy. In conclusion, the scope of medical oncology treatment is getting wider and wider. When choosing treatment, besides the principles of standardized tumor treatment, the specific conditions of patients should also be considered to formulate the drug regimen. Combination therapy is the most commonly used treatment mode at present. Combination therapy should generally follow the following principles: each drug in combination therapy has an effect on tumor; the mechanism of action of each drug is different; the toxicity of each drug is not repeated as much as possible when selecting drugs, so as to improve the tolerance of normal tissues; the number of drugs is generally advocated that 2-3 drugs are the best, too many drugs may not necessarily improve the efficacy. Too many drugs do not necessarily improve the efficacy. Combination chemotherapy can be used sequential therapy of several different drugs and the combination of several drugs at the same time. 2.Monotherapy: For certain special groups of patients, such as poor general condition, intolerant to combination therapy, old age, etc., monotherapy can be used. In addition, the current oral targeted drugs are basically used as single drugs. 3.Special route of drug use: ①Intracavitary therapy: treatment of cancerous effusion, including thoracic, abdominal and pericardial effusion. ②Intrathecal injection: commonly used for the treatment of meningeal leukemia, lymphoma, or other solid tumors with central nervous system invasion. ③Arterial cannulation chemotherapy: Intra-arterial infusion of chemotherapeutic drugs can be used to treat head and neck tumors, primary or metastatic hepatocellular carcinoma, etc. In addition, the route and method of drug administration, drug dose and reasonable interval time should be paid attention to in medical oncology treatment.