Telomerase activity as an indicator of malignant potential in iodine- nonreactive lesions of the esophagus

BACKGROUND. Iodine-nonreactive lesions of esophageal epithelium often are associated with dysplasia and carcinoma. The authors examined the usefulness of telomerase activity as an indicator for esophageal carcinogenesis in such lesions. METHODS. Telomerase activity was measured using the telomeric repeat amplification protocol assay in 18 samples of iodine-nonreactive lesions apart from the primary tumor in surgically resected specimens obtained from patients with esophageal squamous cell carcinoma (ESCC) and 55 endoscopic punch biopsies of iodine-nonreactive lesions obtained from 25 patients with ESCC and 30 patients who had undergone endoscopic examination for other reasons. RESULTS. Ten of 18 iodine- nonreactive samples (56%) obtained from surgically resected specimens showed telomerase activity. In all ten telomerase positive samples, carcinoma in situ (CIS) was observed in iodine-nonreactive mucosa by light microscopy. In eight telomerase negative samples, no tumor tissue was observed in iodine- nonreactive lesions. In a parallel study, telomerase activity was detected in 28 of 55 endoscopic punch biopsy specimens (51%). CIS was observed in 25 of 28 iodine-nonreactive lesions with positive telomerase activity (89%), and tumor tissue was not observed in the other 3 samples (11%), which included 2 cases of severe dysplasia and 1 case of moderate dysplasia. No tumor tissue was observed in any of the 27 telomerase negative samples. CONCLUSIONS. Positive and negative telomerase activity was found to be correlated with the presence and absence, respectively, of immortalized tumor cells in iodine- nonreactive lesions. The measurement of telomerase activity in iodine- nonreactive lesions independently contributes to the selection of an appropriate therapeutic strategy. (C) 2000 American Cancer Society.