DISEASE CHARACTERISTICS:

• Histologically confirmed primary non-small cell lung cancer (NSCLC)

  • Bronchoalveolar carcinoma presenting as discrete solitary radiological mass or nodule allowed
  • Stage IB, II, or IIIA disease

  • Completely resected by lobectomy, sleeve resection, bilobectomy, or pneumonectomy within the past 16 weeks (26 weeks for patients who received adjuvant platinum-based chemotherapy)

    • Mediastinal lymph node resection or lymph node sampling attempted with no evidence of metastatic involvement
    • Patients without a complete mediastinal lymph node resection or lymph node sampling must have undergone biopsy of any mediastinal lymph node measuring 1.5 cm or more on pre-surgical CT/MRI scan or any area of increased uptake in the mediastinum on pre-surgical PET scan
• No combination of small cell and non-small cell carcinoma or pulmonary carcinoid tumor
• No more than 1 discrete area of apparent primary cancer (even within the same lobe)

PATIENT CHARACTERISTICS:

Age

• 18 and over

Performance status

• ECOG 0-2

Life expectancy

• Not specified

Hematopoietic

• WBC at least 3,000/mm^3
• Absolute granulocyte count at least 1,500/mm^3
• Platelet count at least 100,000/mm^3

Hepatic

• Bilirubin normal
• AST/ALT no greater than 2.5 times upper limit of normal (ULN)
• Alkaline phosphatase no greater than 2.5 times ULN

Renal

• Creatinine no greater than 1.5 times ULN

Cardiovascular

• No uncontrolled congestive heart failure
• No angina
• No arrhythmias

Other

• No active uncontrolled infection
• No clinically significant or untreated ophthalmologic conditions (e.g., Sjögren's syndrome)
• No clinically significant or untreated gastrointestinal conditions (e.g., Crohn's disease or ulcerative colitis)
• No other malignancy within the past 5 years except adequately treated nonmelanoma skin cancer or carcinoma in situ of the cervix
• No other concurrent malignancy
• No prior allergic reaction to compounds of similar chemical or biological composition to gefitinib
• No history of psychiatric or neurologic disorder that would preclude study compliance
• No active pathological condition that would preclude study participation
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception during and for 3 months after study participation

PRIOR CONCURRENT THERAPY:

Biologic therapy

• No prior neoadjuvant immunotherapy for NSCLC

Chemotherapy

• See Disease Characteristics
• Prior adjuvant platinum-based chemotherapy allowed
• At least 3 weeks since prior adjuvant platinum-based chemotherapy for NSCLC and recovered
• No prior non-platinum-based chemotherapy
• No prior neoadjuvant chemotherapy for NSCLC

Endocrine therapy

• Not specified

Radiotherapy

• Prior preoperative limited-field, low-dose external beam radiotherapy (less than 1,000 cGy) or endobronchial brachytherapy allowed
• At least 3 weeks since prior radiotherapy and recovered
• No prior full-dose preoperative radiotherapy with curative intent

Surgery

• See Disease Characteristics
• Recovered from prior oncologic or other major surgery

Other

• Prior laser therapy for short-term control of hemoptysis or lobar obstruction allowed
• No other concurrent anticancer therapy
• No concurrent drugs that induce CYP3A4 enzymes (e.g., phenytoin, carbamazepine, barbiturates, rifampin, or Hypericum perforatum [St. John's wort])