<qa>  What is the benefit of first-line maintenance erlotinib?This double-blind, placebo-controlled study will evaluate the benefit of first-line maintenance erlotinib Tarceva versus erlotinib at the time of disease progression in participants with advanced NSCLC who have not progressed following 4 cycles of platinum based-chemotherapy and whose tumor does not harbor an epidermal growth factor receptor EGFR-activating mutation. Participants will be randomized to receive either erlotinib 150 milligrams mg orally PO once daily or placebo. Participants who progress on placebo will receive erlotinib 150 mg PO once daily as second-line therapy, and those who progress on erlotinib may switch to a non-investigational, second-line chemotherapy. Treatments will continue until disease progression, death, or unacceptable toxicity. Participants may also be entered into a final Survival Follow-Up SFU period upon treatment discontinuation. 