Investigation of REcurrence Mechanisms to Adjuvant osimertINib in Radically Resected EGFR-mutated NSCLC Patients

Inclusion Criteria: * Age ≥ 18 years * Diagnosis of radically resected IB-IIIA NSCLC with EGFR activating mutation * Treatment with adjuvant osimertinib (starting from September 2022, date of approval) according to clinical practice * Recurrence of disease during or after adjuvant therapy with osimertinib received according to clinical practice * Availability of tissue and/or liquid biopsy sample collected at the time of recurrence * Signed informed consent. * Exclusion Criteria: * Unavailability of tissue and/or liquid biopsy sample collected at the time of recurrence * Concomitant synchronous malignancies aside from NSCLC or any concurrent and/or active malignancy that has required treatment within 2 years * Involvement in the planning and/or conduct of the study (applies to both investigator staff and/or staff at the study site).