The study aims to randomize 52 patients with advanced (Stage IV) EGFR mutation negative nonsquamous non-small cell lung cancer (NSCLC) who respond (CR/PR/SD) to 4 cycles of pemetrexed / cisplatin or pemetrexed/carboplatin as first-line therapy. In order to achieve that, approximately 144 treatment naïve patients with advanced nonsquamous NSCLC need to be enrolled from around 6 investigational sites in Taiwan that have expertise in lung cancer diagnosis.