From different perspectives of clinical practice, chemotherapy can be classified as follows: 1. Classified according to the relationship between chemotherapy and surgery: ① Postoperative adjuvant chemotherapy: postoperative adjuvant chemotherapy is part of the radical chemotherapy strategy for tumors, which aims at eliminating the residual tiny metastatic foci, reducing the probability of recurrence, eliminating the local implantation that may be caused in the course of surgery, and improving the cure rate of surgical treatment. In chemotherapy, attention should be paid to the recovery of the functions of various organs of the body, and the relationship between attack and complement should be arranged; ② preoperative chemotherapy: also known as neoadjuvant chemotherapy or induction chemotherapy, the purpose of which is to reduce the tumor load, lower the stage of the tumor, eliminate the microscopic metastatic foci at an early stage, and eliminate the possible distant metastases. Neoadjuvant chemotherapy can improve the possibility of surgical resection and complete resection rate, and if the pathological stage can be reduced, it can also increase the chance of cure or prolong the survival period of the patients, in addition, neoadjuvant chemotherapy can also provide the most reliable individualized in vivo drug sensitivity test results for postoperative treatment. In some cases, neoadjuvant chemotherapy can be synchronized with neoadjuvant radiotherapy; ③ The chemotherapy that does not include surgery in the comprehensive treatment of tumors: some tumors can be cured by radical chemotherapy alone, and do not need surgery; some tumors have already reached the advanced stage at the time of diagnosis or recurrence of metastasis, and have lost the opportunity of surgery, so palliative chemotherapy is the main treatment; some tumors are susceptible to metastasis at the early stage and are not treated with surgery, such as SCLC, which is treated with medical oncology. Some tumors are generally not treated with surgery due to the characteristics of metastasis in early stage, such as SCLC, and the main treatment means is medical oncology treatment, including radical treatment and palliative treatment. 2.Classification according to the purpose of chemotherapy ①Palliative chemotherapy: as the name suggests, palliative chemotherapy refers to the role of temporarily relieving patients’ symptoms and controlling their conditions, the treatment program for the purpose of palliative chemotherapy should not bring great risks and pain to patients, and the advantages and disadvantages that may be caused by the treatment must be weighed. Most of the chemotherapy for recurrence and occurrence of distant metastases belongs to this; ② Radical chemotherapy: radical chemotherapy should eliminate tumor cells as much as possible, and adopt necessary consolidation and intensive treatment with a view to achieving cure, for this reason, radical chemotherapy should ensure sufficient intensity, such as leukemia, malignant lymphoma, choriocarcinoma, etc., which can be cured with internal medicine oncology treatment alone, including radical chemotherapy, and in the case of breast cancer, osteosarcoma, In breast cancer, osteosarcoma, testicular tumor, etc., preoperative and/or postoperative chemotherapy is indispensable in the radical treatment. With the progress of tumor treatment means and the emergence of new treatment means, more tumor chemotherapy is in the transition from palliative treatment to radical treatment, and it is necessary to make clear whether the purpose of tumor treatment is palliative or radical before formulating the chemotherapeutic plan and scheme, so as to avoid unnecessary pains suffered by the patients as far as possible, and to avoid the patients missing the rare chance of cure. In order to avoid unnecessary suffering and missing the rare chance of cure. 3.Classified according to the route of chemotherapy: ① Intravenous chemotherapy: it is the most commonly used route of chemotherapy, for lung tumors, using intravenous drug delivery, the drug firstly enters the lungs through the right heart, and the lung tissue receives the largest amount of drug; ②Arterial interventional therapy: theoretically, the drug can be selectively delivered through the arteries to be directly introduced into tumor tissues, and its antitumor effect can be higher than the same dosage of intravenous drug, and the drug that reaches the rest of the body is very little, which can reduce the systemic toxic side effects, but the arterial intervention can reduce the systemic toxic side effects. However, the risk of arterial puncture and catheterization is relatively higher, and the blood supply artery of the tumor is relatively single in order to achieve the purpose of direct drug introduction into the tumor tissue. Arterial intervention has been proved to improve the efficacy of hepatocellular carcinoma and renal carcinoma, and the drugs can be injected into liver and kidney tumors through hepatic and renal arteries, while very few drugs can reach the rest of the body; ③ Oral chemotherapy: the bioavailability of the drugs is affected by the difficulty of drug absorption and the first-pass effect of the liver, and there is a large individual difference in the therapeutic efficacy. The efficacy of cell cycle-specific chemotherapeutic drugs has nothing to do with the peak concentration of the drug, but is more related to the duration of the effective concentration of the drug. The oral dosage forms of pedicel glycosides, 5-fluorouracil and topoisomerase, which can be administered according to the half-life of the drug and maintain the effective concentration for a long time, have been shown to improve clinical efficacy; ③ Intracavitary chemotherapy: In addition to systemic treatment, intracavitary administration can be given simultaneously to patients with pleural, pericardial and abdominal metastasis. ④Intracavitary chemotherapy: for example, patients with pleural dissemination, pericardial dissemination and abdominal metastasis, in addition to systemic treatment, intracavitary drug can be given at the same time, and patients with bladder cancer can be injected into the bladder directly; intracavitary chemotherapy should use the locally effective drugs in their original form, and some drugs need to be metabolized to play anti-tumor effect, which is unsuitable for local perfusion. For example, 1%～5% 5-Fu or 0.1%～0.2% pingyangmycin ointment applied externally is an effective treatment method for skin cancer.