FEZF1 and neuroendocrine neoplasm: According to previous studies, 11% to 30% cases of NSCLC demonstrated expression of neuroendocrine markers despite the absence of neuroendocrine tumor morphological traits.[17–18] Preliminary studies proved that elevated NSE levels was important to discriminate NSCLC and associated with an enhanced drug sensitivity, a more aggressive clinical tumor behavior and larger tumor size.[19–22] In the study, higher plasma FEZF1-AS1 level was associated with larger tumor size and poor prognosis, which was in line with the biological significance of NSE.