Osimertinib to Suppress the Progression of Remaining GGN for EGFR Mutation-positive Stage IB-IIIA Lung Adenocarcinoma

This study is testing whether osimertinib — a targeted lung cancer drug — can prevent the growth of additional small lung lesions (called ground-glass nodules, or GGNs) in patients with EGFR-mutated lung cancer who have already had surgery to remove their main tumor. **You may be eligible if...** - You are 30–75 years old - You have had confirmed lung adenocarcinoma with an EGFR mutation (specifically L858R or exon 19 deletion) and complete surgical removal of the primary tumor - You have additional persistent ground-glass nodules in at least one other part of your lung - You are in good functional health (WHO performance status 0–1) - Your cancer is stage IB–IIIA after surgery (for the treatment arm) or stage IA (for the observation arm) **You may NOT be eligible if...** - You are pregnant or breastfeeding - You had complications recovering from surgery - You have other serious health conditions Talk to your doctor to see if this trial is right for you.