Pazopanib Hydrochloride or a Placebo in Treating Patients With Non-Small Cell Lung Cancer Who Have Received First-Line Chemotherapy

RATIONALE: Pazopanib hydrochloride may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth and by blocking blood flow to the tumor. It is not yet known whether pazopanib hydrochloride is more effective than a placebo in treating patients with non-small cell lung cancer that has not progressed after first-line chemotherapy. PURPOSE: This randomized phase II/III trial is studying how well giving pazopanib hydrochloride works and compares it with giving a placebo in treating patients with non-small cell lung cancer who have received first-line chemotherapy.