Post-operative Radiotherapy After Neodjuvant Chemo-immunotherapy and Surgery in Stage III NSCLC

Inclusion Criteria: 1. Participants must be ≥ 18 years old 2. Ability to provide written informed consent 3. ECOG performance status 0-2 4. Histologically confirmed NSCLC 5. Absence of actionable driver mutation (EGFR/ALK/ROS) 6. Complete preoperative imaging staging, including: FDG-PET and brain imaging to exclude distant metastases will be mandatory. 7. Baseline clinical or post-operative pathological stage III including specifically stage T1-4N2-3 8. Completion of 2-4 cycles of neoadjuvant chemo-IO, regardless of the specific immunotherapy and chemotherapy used. 9. Status post-complete (R0) surgical resection with mediastinal lymph node dissection. 10. Residual nodal disease on final pathology specimen (i.e. absence of pathological complete response). 11. Postoperative lung function examination: FEV1 \> 1 L (or greater than 35% expected value) Exclusion Criteria: 1. Pregnant individuals 2. Previous chest radiotherapy 3. \>24 weeks after thoracic surgery 4. History of other non-cutaneous neoplasms within the last 24 months 5. Active grade ≥ 2 pneumonitis. 6. Presence of interstitial lung disease 7. Recurrence or metastasis occurred 8. Medical conditions that hinders the safe administration of radiotherapy or follow-up.