Clinical trial recruitment “An open, single-arm, multicenter clinical trial to evaluate the efficacy and safety of gefitinib as first-line therapy in patients with EGFR-mutated advanced (stage IV) lung adenocarcinoma as determined by ddPCR in peripheral blood free DNA (BENEFIT trial)” 1. Patients with initial diagnosis of lung adenocarcinoma can be screened 2. If you meet the requirements of the experiment, 10ML of blood will be taken every 2 months in addition to the routine examination. 3.Benefit If EGFR-sensitive mutation can be detected in peripheral blood, you will take Erythroxa for free (the cost of 14,000 per month) until the disease progresses. 4.Possible risks Petechiae may appear at the site of additional blood collection (if pressure is not good).