Mecapegfilgrastim Prevents Neutropenia and Radiation Esophagitis

Inclusion Criteria: * Patients with limited small cell lung cancer diagnosed by histopathology; * ECOG 0-1 points; * Weight ≥ 45 kg; * Age 18-75 years old; * It is expected that at least 2 cycles of EP chemotherapy will be completed as planned; once thiophene penicillin is used, chemotherapy should not be re-dosed within 12 days. * Bone marrow hematopoietic function is normal, no bleeding tendency (INR\<1.5); * Laboratory tests are subject to: (1) Blood routine examination: Hb≥90g/L; WBC≥4.0×109/ L; ANC≥2.0×109/L; PLT≥100×109/L. (2) Liver function, biochemical examination: ALT and AST≤1.5×ULN; TBIL≤1.5×ULN; Serum creatinine≤1.5×ULN. * According to the researcher's judgment, the test plan can be observed; * Volunteer to participate in this clinical trial, understand the research process and be able to sign informed consent in writing. Exclusion Criteria: * There are currently uncontrolled infections or systemic antibiotics within 72 hours of receiving chemotherapy; * Any abnormal bone marrow hyperplasia and other hematopoietic dysfunction; * Patients who have received bone marrow or hematopoietic stem cell transplantation within the past 3 months; * Patients with previous malignant tumors that have not been cured or have brain metastases; * Liver function tests Total bilirubin (TBIL), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) are \>2.5 times the upper limit of normal; if due to liver metastasis, the above indicators are \>5 times the upper limit of normal; * Renal function test: serum creatinine (Cr) \> 1.5 times the upper limit of normal; * Those who are allergic to this product; * suffering from mental or neurological disorders that cannot be matched; * Female patients during pregnancy or lactation; women of childbearing age who refuse to receive contraception; * The investigator believes that it is not suitable for inclusion.