Detection of telomerase activity in bronchial lavage as an adjunct to cytological diagnosis in lung cancer.

Objective: Definitive diagnosis of lung cancer with conventional methods may sometimes be difficult in clinical practice. Telomerase is a ribonucleoprotein DNA polymerase that maintains the telomeric region of chromosomes during successive rounds of cell division. Telomerase activity in body cavity fluids has been advocated to be a potential diagnostic marker for malignancy. We investigated the diagnostic value of telomerase activity in bronchial lavage samples of patients undergoing diagnosis of lung cancer.

Methods: A total of 29 bronchial lavage samples were collected from patients in whom the diagnosis was confirmed with cytological and/or histological examinations. Patients were classified as lung cancer patients (Group 1, n = 22) and patients with benign disease (Group 2, n = 7). Telomerase activity was determined with polymerase chain reaction-based TRAP (The telomeric repeat amplification protocol) assay.

Results: Cytological examination was diagnostic in 12 (54.5%) of 22 patients in Group 1, and in all seven patients of Group 2 (P = 0.063). Telomerase activity was positive in 16 (72.7%) of Group 1 patients, while it was positive in only 1 (14.3%) sample of a lung abscess in Group 2 (P = 0.011). The sensitivity rate of cytological examination when combined with telomerase activity (81.8%) was significantly greater than that of cytological examination alone (54.5%) (P = 0.031). The sensitivity and specificity of telomerase activity were 72.7 and 85.7%, respectively. Telomerase activity had a positive predictive value as 0.94 and negative predictive value as 0.50. Diagnostic accuracy of telomerase activity was 75.8%.

Conclusion: Telomerase activity in bronchial lavage is a highly sensitive diagnostic biomarker for malignancy and a potential complementary diagnostic technique to cytological examination in the diagnosis of lung cancer.