Telomerase activity in sputum and telomerase and its components in biopsies of advanced lung cancer

PurposeIn this study, we explored the diagnostic utility of sputum telomerase activity as a non-invasive biomarker of lung cancer. In biopsies of lung cancer, the relationship of telomerase activity to telomerase reverse transcriptase (hTERT) and telomerase RNA component (hTERC) and to c-Myc expression was also evaluated.MethodsPaired biopsy and sputum samples were evaluated for telomerase activity by the telomerase repeat amplification protocol (TRAP) assay in 34 cases of lung cancer and in 30 control subjects without any evidence of lung cancer. hTERT and hTERC transcript expression was evaluated in 42 cases of lung cancer and compared to telomerase activity and c-Myc transcript expression.ResultsTelomerase activity was present in 85.2% of biopsies and in 67.6% of paired sputum with a good concordance. Three out of the 30 negative controls showed a weak telomerase activity, all of whom had sarcoidosis. Thus, sputum telomerase activity had sensitivity, specificity, Negative Predictive Value and Positive Predictive Value of 67.6%, 90%, 71% and 88.46%, respectively. The hTERT levels correlated to the telomerase activity but not to the c-Myc oncogene expression.ConclusionsIn lung cancer, sputum telomerase activity is a candidate non-invasive biomarker of malignancy.