Due to CYFRA21-1 and SCC that are considered to be markers of squamous cell lung cancer instead of adenocarcinoma lung cancer, meanwhile, NSE and ProGRP representing SCLC which accounts for only a small proportion of whole lung cancer population and has less PE prevalence than NSCLC does [24–26], the predictive power of these tumor markers could be depreciated. Here, ENO2 is linked to small cell lung carcinoma.