II. To evaluate the safety profile of erlotinib in the adjuvant setting. III. To assess whether adjuvant therapy with erlotinib will result in improved DFS rate at 2 years, and OS rate at 5 and 10 years over observation for patients with completely resected stage IB (>= 4 cm)-IIIA EGFR mutant NSCLC (confirmed centrally) following complete resection and standard post-operative therapy, both overall and within the stage subgroups: IB and II/IIIA.