Ma et al. [20] studied the prognostic value of CA 19–9, NSE, Squamous cell carcinoma antigen (SCC) and Cytokeratin 19 fragment (CYFRA21.1) in serum in stage I NSCLC and showed that CYFRA21.1, but none of the other tumor markers, might be a prognostic marker. The gene discussed is ENO2; the disease is non-small cell lung carcinoma.