DISEASE CHARACTERISTICS: Histologically confirmed non-small cell lung cancer (NSCLC), including: Squamous cell carcinoma Undifferentiated carcinoma Adenocarcinoma Mixed (i.e., adenocarcinoma with squamous cell carcinoma) No mixed tumors containing small cell lung carcinoma elements Bronchoalveolar carcinoma Large cell carcinoma Bronchoalveolar lavage allowed for diagnosis Advanced or metastatic NSCLC Stage IIIB disease ineligible for combined chemotherapy and radiotherapy OR Stage IV disease Progressive NSCLC during or after first-line therapies with platinum-containing chemotherapy regimens in the advanced or metastatic setting Measurable disease by radiological imaging techniques Previously treated CNS metastases allowed provided: Neurologically stable Oral or IV steroids or anticonvulsants not required No active disease by CT scan or MRI No known leptomeningeal metastases or carcinomatous meningitis