Background: Finding suitable tumor markers with higher sensitivity and specificity for malignancy could be a fine approach to early diagnosis, response to treatment and follow up after treatment in cancers. The aim of this study was to compare the sensitivity and specificity of telomerase enzyme with carcinoembryogenic antigen (CEA), Cyfra21-1 and parathyroid hormone (PTH), in diagnosis of patients with lung cancer and other cancerous diseases visited in Lung and Tuberculosis Research Center of Tabriz Medical University.

Materials and Methods: In this research a diagnostic value was designed on 50 lung cancer patients and 20 normal individuals. Telomerase activity was measured by TRAP assay, based on PCR- ELSA, in lung tumor biopsies. The serum levels of PTH, CEA, and Cyfra-21-1 were measured using commercially available immunoassay kits. Sensitivity, specificity and other diagnostic value markers were calculated. To compare quantitative means of the two groups, T independent and Man-Whitney analysis were applied.

Results: Telomerase activity had the highest sensitivity and accuracy (76% and 82.9%, respectively). The mean values for Cyfra-21-1 were 58% and 70%, respectively. The highest value of sensitivity for telomerase was calculated in small and large cell carcinoma with 100% in lung cancer patients. The highest sensitivity of Cyfra-21-1 (98%) was seen in the large cell carcinoma.

Conclusion:  The diagnostic sensitivity of telomerase enzyme was higher than that of cyfra21-1 and CEA. It seems that the positive value of telomerase enzyme could be considered as a rapid diagnostic factor especially in lower stages of lung cancer.