The significance of telomerase activity in cancer lesions and the noncancerous epithelium of the esophagus

It is well known that telomerase activity is expressed in cancer cells. A recent study has revealed that weak telomerase activity was also detected in normal cells. Telomerase activity is thus thought to be useful as a diagnostic biomarker. In the present study, we studied the difference in telomerase activity between cancer tissue and noncancerous epithelium tissue of the esophagus. One hundred and thirty specimens of esophageal cancer tissue were collected at surgery and analyzed in a telomeric repeat amplification protocol (TRAP) assay. Telomerase was expressed quantitatively as the total product generated (TPG) value. Telomerase activity was detected in all esophageal cancer tissues and in 87% of the noncancerous epithelium specimens. The mean TPG values in the cancer tissue and the noncancerous epithelium specimens were 49.5 +/- 39.5 (mean +/- 1 SD) and 11.5 +/- 5.9, respectively, with a significant difference (P < 0.0001). The telomerase activity in esophageal cancers was significantly higher than that in the noncancerous epithelium. From the mean value plus 1 SD for noncancerous epithelium, the cutoff value was set at 17.4 as an esophageal cancer-specific diagnostic marker. This cutoff value showed a high predictive value, specificity, and sensitivity, of greater than 80% for each category. These results suggest that this cutoff value could be a useful biomarker for the detection of esophageal carcinoma.