ENO2 and lung cancer: Excessive NSE expression occurs in tumors associated with the origin of neuroendocrine tissues, especially SCLC, leading to a significant increase of serum NSE concentration.6 ProGRP31-98 is a hormone which is frequently produced by SCLC cells.7 The sensitive and accurate determinations of NSE and ProGRP31-98 show great significance and high potential in disease surveillance, early diagnosis and prognostic judgment of lung cancer.