Gefitinib in Treating Patients With Stage IIIA Non-Small Cell Lung Cancer

DISEASE CHARACTERISTICS: * Biopsy-proven stage IIIA nonsquamous non-small cell lung cancer * pN2 disease proven by mediastinoscopy * Meets any of the following criteria: * Never smoked * EGFR mutations (in exon 18, 19, or 21)\* * FISH positive for EGFR\* NOTE: \*Irrespective of smoking history * Presence of at least 1 unidimensionally measurable lesion on thoracic CT scan, according to RECIST * Feasible to undergo pneumonectomy or lobectomy PATIENT CHARACTERISTICS: Inclusion criteria: * ECOG performance status 0-1 * FEV\_1 ≥ 2.0 L in preoperative pulmonary function test * Hemoglobin ≥ 9.0 g/dL * WBC 4,000-12,000/μL * ANC ≥ 1,500/μL * Platelet count ≥ 100,000/mm³ * Total bilirubin ≤ 1.5 times upper limit of normal (ULN) * Alkaline phosphatase ≤ 3.0 times ULN * AST and ALT ≤ 3.0 times ULN * Creatinine ≤ 1.5 times ULN * Negative pregnancy test Exclusion criteria: * Severe complications or infections * Pregnant or breast-feeding women * Clinically significant heart disease * Uncontrolled hepatitis, chronic liver disease, or diabetes mellitus * Another active cancer except properly treated carcinoma in situ of the cervix or basal/squamous cell skin carcinoma PRIOR CONCURRENT THERAPY: * No prior radiotherapy, chemotherapy, hormone therapy, or target therapy * No other concurrent systemic anticancer therapies, including experimental drugs, chemotherapy, immunotherapy, or radiotherapy