Dose-Escalation Radiotherapy in Limited-Stage Small Cell Lung Cancer: A Phase III Randomized Trial

Inclusion Criteria: * Histologically confirmed diagnosis of small cell lung cancer (SCLC) * Limited-stage disease (Stage I-III; any T, any N, M0), eligible for definitive radiotherapy * Measurable disease according to RECIST 1.1 * Age ≥18 years * ECOG performance status 0-2 * No prior thoracic radiotherapy * Signed informed consent * Adequate hematologic function: WBC ≥3.0×10⁹/L, neutrophils ≥1.5×10⁹/L, platelets ≥100×10⁹/L, hemoglobin ≥90 g/L * Adequate liver and renal function: total bilirubin ≤1.5×ULN, AST/ALT ≤1.5×ULN, creatinine normal or CrCl ≥60 mL/min * Pulmonary function: FEV1 \>1 L or \>30% predicted; DLCO \>30% predicted Exclusion Criteria: * Prior surgery or radiotherapy for any lung cancer (SCLC or NSCLC) * Presence of malignant cells in pleural or pericardial effusion * Serious uncontrolled systemic disorders (e.g., active infection, unstable cardiovascular disease) * Medical, psychological, or social conditions that could interfere with compliance * Active malignancy other than SCLC (except localized prostate/breast cancer or basal cell carcinoma) * Refusal or inability to sign informed consent