With the emergence of new chemotherapeutic drugs, the status of chemotherapy in the treatment of malignant tumors is also increasing. Since the selectivity of anticancer drugs is still not high, they have damaging effects on normal cells of the body while killing tumor cells, especially on proliferating cells such as bone marrow cells. Bone marrow suppression is the most common toxic reaction of cancer chemotherapy, among which leukocytes, especially neutrophils, are the most common and the earliest to appear, followed by thrombocytopenia, while peripheral red blood cell count and hemoglobin amount are relatively less decreased. The degree of bone marrow damage caused by anticancer drugs is related to the type of drug, dosage, number of treatment cycles, patient’s age, liver and kidney function, combined with the same drug and other factors. Severe bone marrow suppression can be combined with infection, bleeding and even life threatening. Therefore, it is very important to correctly understand the myelosuppression caused by chemotherapy and to master its treatment. I. Clinical application of colony-stimulating factor (CSF) Colony-stimulating factor (CSF) is a group of multipotential hematopoietic cell growth factors. With the progress of bioengineering technology, a variety of CSFs have entered the clinic in recent years. Currently, the main CSFs used in clinical practice to prevent granulocytopenia after chemotherapy are granulocyte monocyte macrophage colony-stimulating factor (GM-CSF) and granulocyte colony-stimulating factor (G-CSF). Although there are some differences in the mechanisms of action of these two CSFs, both have significant therapeutic effects on granulocytopenia caused by tumor chemotherapy. According to whether patients are febrile or not, the application of CSF can be divided into two categories: non-febrile and febrile therapeutic drugs. For patients with neutropenia without fever after chemotherapy, there is a lack of sufficient information on whether the application of G-CSF is beneficial to the patient. Therefore, GM-CSF or G-CSF is not recommended for patients with neutropenia without fever, but there is a lot of literature suggesting that GM-CSF or G-CSF can shorten the time to normalize neutrophil count in patients with non-febrile neutropenia caused by radiotherapy and chemotherapy. 2. Treatment of febrile neutropenia Although the results of some randomized controlled studies have shown that GM-CSF or G-CSF treatment for febrile neutropenia can significantly shorten the time to normalize the neutrophil count and the time to normalize the body temperature in febrile patients, there is not enough information to prove its usefulness. Therefore, the routine use of GM-CSF or G-CSF is still not recommended in patients with post-chemotherapy neutropenia with fever without other complications. certain patients with febrile neutropenia who are at high risk of infection-related complications and have factors predictive of adverse clinical outcomes (e.g., uncontrollable primary lesions, pneumonia, hypotension, multiple organ function abnormalities, invasive fungal infections, etc.) The application of GM-CSF or G-CSF may be considered. Second, the clinical application of antimicrobials Patients with neutropenia after chemotherapy, but without fever, do not require routine prophylactic use of antimicrobials. In the “Guidelines for the Clinical Use of Antimicrobial Agents in Patients with Neutropenia in Oncology 2002”, after analyzing a large amount of literature, it is pointed out that: when the body temperature (oral thermometry) is higher than 38.3℃ once or when the temperature is higher than 38℃ twice at an interval of more than two hours, the use of antimicrobial agents can be considered, and the use of broad-spectrum antimicrobial agents is preferred. Since the axillary temperature measurement method is generally used in China, I think the temperature standard should be slightly lower than that in the United States. In addition, when neutropenia is present after chemotherapy, although there is no fever, but there are symptoms or signs of combined infection, antimicrobial agents should be empirically selected for treatment. Third, the clinical application of antifungal and antiviral drugs The results of several clinical trials suggest that: patients with neutropenia after chemotherapy should consider the empirical use of antifungal drugs when they still have fever after 5-7 days of antimicrobial drug treatment or when fever reappears after the body temperature has once returned to normal. Usually antivirals are not routinely used prophylactically in chemotherapy. In patients with neutropenia with fever after chemotherapy, routine use of antiviral drugs is also not recommended if there is no clear evidence of viral infection. However, patients with oncology combined with herpes simplex or herpes zoster should be treated with antiviral drugs as soon as possible. Treatment of anemia caused by chemotherapy Anemia in tumor patients is mostly caused by chronic onset and low bone marrow function. When hemoglobin is above 100g/L, there is no indication for blood transfusion. When hemoglobin is below 85g/L, transfusion of concentrated red blood cells can be considered in combination with clinical manifestations of patients, such as extreme fatigue, dizziness, headache, tachycardia, hypotension and myocardial ischemia. With hemoglobin below 70 g/L, red blood cell concentrate is usually given. With the synthesis of the EPO genetic engineering product rHuEPO, EPO has become widely used for the treatment of chemotherapy-associated anemia. The application of rHuEPO is subject to the following conditions:erythrocyte specific volume (HCT).