Currently the investigators have two different classes of second-line treatment options in recurrent non-small Cell Lung Cancer (NSCLC). In chemotherapy, docetaxel and pemetrexed produced similar treatment efficacy outcomes, while pemetrexed had a better tolerability. In recent analysis of pemetrexed clinical studies, a strong treatment-by-histology interaction in overall survival and progression free survival that indicated better efficacy for non-squamous patients treated with pemetrexed. These data supports that pemetrexed could be a preferable chemotherapy drug especially in adenocarcinoma NSCLC patients.