DISEASE CHARACTERISTICS: Histologically confirmed non-small cell lung cancer (NSCLC) Recurrent AND/OR Stage IIIB with pleural or pericardial effusion OR Stage IV Must have at least one bidimensionally measurable lesion Must be HER2 positive (1-3+) Brain metastases allowed, if symptoms controlled and not requiring steroids Prior/Concurrent Therapy-- Biologic therapy: Not specified Chemotherapy: No prior chemotherapy for NSCLC Endocrine therapy: No concurrent steroids Radiotherapy: At least 2 weeks since prior radiotherapy Surgery: Not specified