A comparative study of telomerase activity in sputum, bronchial washing and biopsy specimens of lung cancer

The potential of telomerase, the ribonucleoprotein enzyme, as a non-invasiv e screening marker was studied in pre-bronchoscopy sputum (S), bronchial wa shings (W) and bronchoscopic biopsy (B) samples from individuals under eval uation for lung cancer. Out of the 52 cases studied, 42 were clinically sus pected primary lung cancer patients and 10 had pulmonary disorders but had no clinical evidence of lung cancer. Fifteen (39.5%) S samples, 24 (63.1%) W samples and 32 (84.2%) B samples. which were cytologically/histopathologi cally positive were also positive for telomerase activity. Interestingly, 1 6 (42%) S samples, 20 (52.6%) W samples and 20 (52.6%) B samples, initially reported cytologically/histopathologically negative: showed detectable tel omerase activity. Lung cancer was finally confirmed in these cases by repea l cytology/histopathology. However, telomerase activity was detected in 31 (81.6%) S, 26 (68.4%) W and 33 (86.8%) B samples of suspected lung cancer p atients. Telomerase activity was negative in S, W, and B of four of the sus pected cases, which ultimately turned out to be negative for lung cancer. C ytopathology/histopathology alone (including repeat attempts) identified 15 (39.5%) cases of sputum, 24 (63.1%) cases of bronchial washings and 32 (84 .2%) bronchoscopic biopsy samples. Out of 10 controls, low telomerase activ ity was detected in only one (10%) of the bronchial washings, which later t urned out to be due to large number of inflammatory cells. Telomerase activ ity assay of sputum carried sensitivity, specificity and diagnostic accurac y of 81.6, 100 and 86.5%, respectively, while that for bronchial washing wa s 68.4, 100 and 76.9%, respectively, and for bronchoscopic biopsy samples w as 86.8, 100 and 88.1%, respectively. A positive correlation (P < 0.01) was seen between age and telomerase activity in sputum, bronchial washing and biopsy samples but no significant correlation was seen between sex and telo merase activity or duration of smoking and telomerase activity. A significa nt positive correlation was observed between staging and telomerase activit y in sputum (P <less than> 0.01), bronchial washing (P < 0.01) and biopsy s amples (P < 0.01). Our findings indicate that telomerase is a specific mark er for malignant lung disease and can complement cytology/histopathology in the diagnosis of lung cancer. Sputum telomerase assay holds the potential for early and non-invasive diagnosis of lung cancer. (C) 2001 Elsevier Scie nce Ireland Ltd. All rights reserved.