Inclusion Criteria:
1. Patients voluntarily participated in this study, signed an informed consent form, and demonstrated good compliance.
2. They were histologically or cytologically confirmed with limited-stage small-cell lung cancer (TNM stage; T1-3N0-2M0).
3. The age range was 18 to 75 years, with no gender restriction.
4. Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) score: 0-2.
5. Life expectancy was estimated to be at least 3 months.
6. No previous anti-tumor treatment specifically for SCLC was administered.
7. According to the Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 criteria, there must be at least one measurable lesion.
8. Patients' organ functions must be adequately sufficient, with the following requirements to be met before the first study treatment:
1. Hematological parameters: ANC ≥1.5×10\^9/L, platelets ≥100×10\^9/L, hemoglobin ≥90g/L.
2. Renal function: serum creatinine ≤1.5 times the upper limit, or creatinine clearance ≥50 mL/min.
3. Liver function: ALT/AST ≤2.5 times the upper limit, total serum bilirubin ≤2 times the upper limit.
4. Coagulation: INR should be ≤ 1.5 times the upper limit.
9. Patients of childbearing potential must agree to use contraception.
10. Patients must be able to tolerate chemotherapy, immunotherapy, and surgery.
Exclusion Criteria:
1. Patients who have received anti-tumor treatment for SCLC (including but not limited to chemotherapy and radiation therapy at the site of the lesion).
2. Patients who have previously used immune checkpoint inhibitors such as PD-1/PD-L1 inhibitors for treatment.
3. Patients with a history of interstitial lung disease, non-infectious pneumonia, or uncontrollable systemic diseases, including pulmonary fibrosis and acute lung disease.
4. Patients requiring systemic anti-bacterial, anti-fungal, or anti-viral treatment for severe chronic or active infections, including tuberculosis.
5. Patients known to have HIV.
6. Patients with active hepatitis B or hepatitis C.
7. Patients with active autoimmune diseases or a history of autoimmune diseases that may recur.
8. Patients with diseases requiring systemic corticosteroid treatment or other immunosuppressive therapy.
9. Patients deemed by the investigator to have concomitant diseases that pose a serious risk to patient safety or could affect the patient's ability to complete the study.
10. Patients who have undergone major surgery within 4 weeks prior to treatment initiation, or those with significant trauma or fractures, or those with unhealed wounds at the time of treatment.
11. Patients with severe cardiac diseases, such as NYHA class III or higher congestive heart failure, CCS class III or higher angina, a history of myocardial infarction in the past 6 months, or arrhythmias requiring medication.
12. Patients with comorbidities that make them unsuitable for surgery.
13. Patients who have had an allergic reaction to the study drug or excipients in the medication.
