Combination Chemotherapy in Treating Patients With Stage IIIB, Stage IV, or Recurrent Non-Small Cell Lung Cancer

RATIONALE: Drugs used in chemotherapy such as gemcitabine, carboplatin, and paclitaxel 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 chemotherapy regimen is more effective in treating non-small cell lung cancer. PURPOSE: Randomized phase III trial to compare the effectiveness of different combination chemotherapy regimens in treating patients who have stage IIIB, stage IV, or recurrent non-small cell lung cancer.