• Patients aged from 18 to 80 years old;

• patients with NSCLC confirmed by needle aspiration cytology or surgical pathology, who cannot undergo radical surgery due to recurrence, metastasis or patient's own conditions;

• Has completed 2-4 cycles of first-line therapy (including chemotherapy, immunotherapy, chemotherapy combined with immunotherapy, chemotherapy combined with targeted therapy, etc.), and has SD assessed by RECIST 1.1 during the same period;

• Patients had at least one measurable lesion;

• No local radiotherapy for primary or metastatic lesions within 28 days;

• ECOG score 0-2;

• Expected survival time ≥3 months;

• Voluntarily participate and sign informed consent.