Combination Chemotherapy, Radiation Therapy, and Gefitinib in Treating Patients With Stage III Non-Small Cell Lung Cancer

Inclusion Criteria:

* Histologically or cytologically documented non-small cell lung cancer (NSCLC), including squamous cell carcinoma, adenocarcinoma (including bronchoalveolar cell), and large cell anaplastic carcinoma (including giant and clear cell carcinomas)
* ELIGIBLE DISEASE STAGES: Inoperable IIIA and selected IIIB

  * Generally, patients entered must be considered unresectable or inoperable; patients with T1 or T2, N2 disease are eligible; patients with T3, N2 or T4, N0-N2 disease are eligible if based on the closeness to the carina, invasion of the mediastinum or invasion of the chest wall; patients with T3, N0-N1 disease are not eligible; patients must be M0 (M1 patients are not eligible)

    * Patients with direct invasion of vertebral body are ineligible
    * Patients with tumors adjacent to a vertebral body are eligible, unless there is demonstrable bone invasion, as long as all gross disease can be encompassed in the radiation boost field in accordance with the homogeneity criteria
    * Patients with contralateral mediastinal disease (N3) are eligible if all gross disease can be encompassed in the radiation boost field in accordance with the homogeneity criteria; patients with scalene, supraclavicular, or contralateral hilar node involvement are ineligible
    * Patients with a pleural effusion, which is a transudate, cytologically negative and non-bloody, are eligible if the radiation oncologist feels the tumor can be encompassed within a reasonable field of radiotherapy. Patients with exudative, bloody, or cytologically malignant effusions are not eligible; if a pleural effusion can be seen on the chest computed tomography (CT) but not on chest x-ray (CXR) and is too small to tap, the patient will be eligible; a pleural effusion appearing only after a thoracotomy or other invasive thoracic procedure was attempted will not make a patient ineligible
* PATIENTS MUST HAVE MEASURABLE DISEASE

  * Lesions that can be accurately measured in at least one dimension (longest diameter to be recorded) as \>= 20 mm with conventional techniques or as ≥10 mm with spiral CT scan
  * Lesions that are not considered measurable include the following:

    * Bone lesions
    * Leptomeningeal disease
    * Ascites
    * Pleural/pericardial effusion
    * Abdominal masses that are not confirmed and followed by imaging techniques
    * Cystic lesions
    * Tumor lesions situated in a previously irradiated area
* PRIOR THERAPY

  * \>= 2 weeks since formal exploratory thoracotomy.
  * No prior chemotherapy or radiation therapy for NSCLC
* CTC performance status 0-2
* No "currently active" second malignancy other than non-melanoma skin cancers; patients are not considered to have a "currently active" malignancy if they have completed therapy and are considered by their physician to be at less than 30% risk of relapse
* Non-pregnant and non-nursing because of significant risk to the fetus/infant
* No patients with uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirements
* No patients with chronic gastrointestinal disorders including liver disease, diarrheal or emetic disorders, or malabsorptive conditions which could worsen toxicity or limit efficacy of ZD1839
* No cytochrome P450 3A4 (CYP3A4) inducers within 7 days prior to starting protocol therapy and while on protocol treatment. CYP3A4 inducers: phenytoin, carbamazepine, barbiturates, rifampicin, dexamethasone, and St John's Wort; single doses of dexamethasone used as an antiemetic are permitted
* No human immunodeficiency virus (HIV)-positive patients receiving combination anti-retroviral therapy
* Granulocytes \>= 1,500/ul
* Platelets \>= 100,000/ul
* Calculated creatinine clearance \>= 20 cc/min
* Bilirubin \< 1.5 mg/dl
* Aspartate aminotransferase (AST) (serum glutamic oxaloacetic transaminase \[SGOT\]) \< 2 x upper limit of normal (ULN)