Gemcitabine and Carboplatin Followed By Docetaxel in Treating Patients With Stage IIIB or Stage IV Non-Small Cell Lung Cancer

RATIONALE: Drugs used in chemotherapy, such as gemcitabine, carboplatin, and docetaxel, use different ways to stop tumor cells from dividing so they stop growing or die. Combining more than one drug may kill more tumor cells. It is not yet known which treatment regimen is more effective for stage IIIB or stage IV non-small cell lung cancer. PURPOSE: Randomized phase III trial to compare the effectiveness of gemcitabine and carboplatin followed immediately by docetaxel with that of giving delayed docetaxel in treating patients who have stage IIIB or stage IV non-small cell lung cancer.