ERCC1 and lung adenocarcinoma: Recently, thymidylate synthase (TS) and excision repair cross-complementation group 1 (ERCC1) showed promise as predictive biomarkers for pemetrexed and platinum-based agents, respectively; however, these biomarkers must be assessed in tumor tissues and have not been validated prospectively in patients with lung adenocarcinoma [6,7].