This study aims to explore the safety and efficacy of eliminating the PTV (planning target volume) margins based on online adaptive stereotactic radiotherapy for patients with early-stage non-small cell lung cancer (NSCLC) or pulmonary oligometastases.

This study aims to explore the safety and efficacy of eliminating the PTV expansion margin based on online adaptive stereotactic body radiotherapy (SBRT) for early-stage non-small cell lung cancer (NSCLC) or pulmonary oligometastases. In this study, patients will be stratified according to whether they have primary early-stage NSCLC, then randomly assigned in a 1:1 ratio to the study group or the control group. Patients in the study group will receive online adaptive SBRT (without PTV expansion margin), while patients in the control group will receive conventional standard SBRT. After the completion of treatment, patients will be followed up regularly to assess safety and efficacy.

Inclusion Criteria:

• Histologically or PET-CT confirmed untreated early-stage non-small cell lung cancer (T1-2N0M0) that is inoperable or where the patient is unwilling to undergo surgery, or PET-CT/chest CT confirmed lung oligometastases (number of metastases ≤3, single lesion diameter ≤5cm).
• Age 18 years or older, regardless of gender.
• ECOG performance status score of 0-2.
• Serum hemoglobin ≥ 80 g/L, platelets ≥ 100,000/μL, absolute neutrophil count ≥ 1,500/μL.
• Serum creatinine ≤ 1.25 times the upper normal limit (UNL) or creatinine clearance ≥ 60 ml/min.
• Serum bilirubin ≤ 1.5 times UNL, AST (SGOT) and ALT (SGPT) ≤ 2.5 times UNL, alkaline phosphatase ≤ 5 times UNL.
• FEV1 ≥ 0.5 L.
• Normal CB6 range.
• The patient and their family agree and sign the informed consent form.

Exclusion Criteria:

• Tumors with bronchial invasion are excluded.
• Any other disease or condition that contraindicates radiotherapy (e.g., active infections, within 6 months post-myocardial infarction, symptomatic heart disease including unstable angina, congestive heart failure, or uncontrolled arrhythmias).
• Pregnant or breastfeeding women, women who have not undergone pregnancy testing, and pregnant individuals.
• Individuals with substance abuse issues, chronic alcoholism, or AIDS.
• Individuals with uncontrollable seizures or loss of self-control due to psychiatric disorders.
• Individuals with a history of severe allergies or specific sensitivities.