The diagnostic characteristics of various tumor markers CA-62, CEA, CA 15-3, NSE, SA-125, CA 19-9, CYFRA 21–1 and SCC were compared for 304 serum samples of patients, including 141 NSCLC (Stage I-III), 133 samples from healthy volunteers and 30 samples from COPD patients in a blind clinical study. Here, ENO2 is linked to chronic obstructive pulmonary disease.