Follow-up and assessment of clinical outcomes

Postoperative clinical follow-up was performed every 6 months. PET/CT or thin-section CT and brain MRI were performed for systemic evaluation every year for at least 5 years after surgery. Evidence of recurrence or death was obtained from the medical records. Local recurrence was defined as ipsilateral intrathoracic lymph node metastasis, recurrence at the surgical stump, or dissemination in the ipsilateral thoracic cavity. Distant metastasis was defined as the lack of these findings.