Clinical utility of telomerase for the diagnosis of malignant well-differentiated endocrine tumours.

Objective: The distinction between benign and malignant well-differentiated endocrine tumours is hard to achieve. The aim of the present study was to determine whether detection of telomerase or quantification of human telomerase reverse transcriptase protein subunit (hTERT) differ between benign and malignant endocrine tumours.

Patients And Methods: This retrospective study investigated 31 well-differentiated primary endocrine tumours. Based on clinical and histopathological criteria, tumours were categorized with the most recent WHO classification as 'benign' (n = 14), 'uncertain' (n = 5) or 'malignant' (n = 12) with (n = 7) or without (n = 5) metastasis after a mean follow-up of 40.4 +/- 25.8 months (4-122 months). All these tumours were assayed for telomerase activity and hTERT mRNA expression [real-time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR)].

Results: Telomerase activity was detected in 7 malignant and metastatic tumours, in 1 malignant tumour without metastases, in 1 uncertain tumour and in 1 benign tumour. hTERT mRNA levels were significantly higher in malignant endocrine tumours with or without metastases (P = 0.001) when compared to benign tumours. The negative predictive value of hTERT mRNA quantification for the diagnosis of malignancy was 88.9%, whereas the positive predictive value was 68.7%.

Conclusion: The presence of telomerase activity within the primary endocrine tumour might indicate a malignant tumour and might suggest the need for an attentive search for concomitant metastases. Quantification of hTERT mRNA could be used in clinical practice to exclude malignancy in most endocrine tumours.