Combined Atezolizumab and Chemotherapy (Carboplatin Plus Etoposide) in Neoadjuvant Treating Limited-Stage Small Cell Lung Cancer Patients

Inclusion Criteria: 1. Patients must be volunteered to participate in the clinical trial. Patients must sign the informed Consent form (ICF) and be willing to follow and able to complete all test procedures. 2. Histologically or cytologically confirmed stage IIb-IIIb SCLC. 3. Patients with good physical condition and good organ function. 4. Previously untreated patients. 5. Patients must have measurable disease based on Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 6. Patients can tolerate chemotherapy, immunotherapy, and surgery. Exclusion Criteria: 1. Unclear diagnosis of SCLC. 2. Contraindicated chemotherapy, immunotherapy, and surgery. 3. Undergoing other active malignancies within 5 years or at the same time.Patients with localized curable tumors, such as basal cell carcinoma, squamous cell carcinoma, superficial bladder carcinoma, prostate carcinoma in situ, cervical carcinoma in situ, or breast carcinoma in situ, will not be excluded. 4. Positive test result for human immunodeficiency virus (HIV). 5. Positive test result for active tuberculosis. 6. Pregnant or lactating women 7. A history of psychotropic substance abuse, drug abuse, or alcoholism. 8. Other factors assessed by the sponsors.