ENO2 and small cell lung carcinoma: When discriminating SCLC from NSCLC, the cut‐off value of proGRP was 114.35 pg/mL and of NSE was 17.34 μg/L (where the Youden Index was maximal); both the sensitivity was 86.5%, while the specificity of proGRP was 99.1% and of NSE was 84.2%; AUC of proGRP was 0.939, which was higher than that of NSE (0.886).