ENO2 and small cell lung carcinoma: Some limitations existed in our study: in this prospective single-armed study, the sample size that included 136 SCLC patients is relatively small, which means a large sample size study is needed in the future; the cut-off value of NSE and ProGRP in our study was the median value, which might result in some bias in this study; and the median follow-up was 29 months, which is a relatively short follow-up period.