A Multi-omics Sequencing-based Model for Predicting Efficacy and Dynamic Monitoring of Treatment in Small Cell Lung Cancer

Inclusion Criteria: * Patients meeting the following criteria may have samples collected: 1. Voluntary signing of informed consent; 2. Age ≥18 years; 3. Expected survival time ≥3 months; 4. Eastern Cooperative Oncology Group (ECOG) performance status score of 0 or 1; 5. Treatment-naïve limited-stage or extensive-stage SCLC confirmed by histology or cytology; 6. Agreement to provide blood samples and paraffin-embedded samples; 7. Measurable target lesions for efficacy evaluation. Exclusion Criteria: * Patients with any of the following conditions will be excluded from sample collection: 1. Archived tumor tissue or pre-treatment tumor biopsy or histological examination showing previous histological or cytological evidence of non-small cell or small cell/non-small cell mixed components; 2. Investigator-determined unsuitability for peripheral blood collection due to complications or other conditions; 3. Active, known, or suspected autoimmune disease (excluding vitiligo, type I diabetes, residual hypothyroidism caused by autoimmune thyroiditis requiring only hormone replacement therapy, or conditions not expected to recur without external stimulation); 4. Active tuberculosis (TB) infection based on chest X-ray, sputum examination, and clinical examination. Patients with active pulmonary TB infection history within the previous year should be excluded even if treated. Patients with active pulmonary TB infection history more than one year ago should also be excluded unless previous anti-TB treatment can be proven adequately effective; 5. Comorbidities requiring immunosuppressive drug treatment, or requiring systemic or local corticosteroid use at immunosuppressive doses; 6. Pregnancy or lactation; 7. Positive human immunodeficiency virus antibody (HIVAb), active hepatitis B virus infection (HBsAg positive and HBV-DNA \>10³ copies/ml), or hepatitis C virus infection (HCV antibody positive and HCV-RNA \> lower limit of detection at study center); 8. History of severe neurological or psychiatric disorders, including but not limited to: dementia, depression, seizures, bipolar disorder, etc.; 9. Use of any anti-tumor drugs before blood sample collection; 10. Previous history of other malignant tumors (excluding non-melanoma skin cancer and the following carcinoma in situ: bladder, gastric, colon, endometrial, cervical/dysplasia, melanoma, or breast cancer); 11. Patients receiving live vaccines within 28 days before blood sample collection.