Topoisomerase II α and telomerase expression in papillary thyroid carcinomas

Background. Altered topoisomerase II α (Topo II α) expression and telomerase activity (TA) reflect tumour cell growth and malignant transformation. Methods. We examined TA by using a TRAP assay and expression of Topo II α by immunohistochemical analysis in a series of 27 cases of papillary thyroid carcinoma (PTC). Results. Topo II α labelling index (LI) ranged from 0.1 to 4.2% and was significantly associated with patient age (r=−0.42, p=0.003), with higher levels of Topo II α in patients under 40 years. There was no relationship between Topo II α LI, AGES score or other clinical outcome. TA was detected in 14 PTC, with relative levels ranging from 1.2 to 102 units. A significant positive correlation between the multiplicity of tumoral foci and the TA levels (p<10−2) was noted. Conclusion. We concluded that Topo II α cannot be used as a marker of tumour aggressiveness. Furthermore, enhanced Topo II α expression in PTCs from patients less than 40 years old suggests that this age group might benefit from Topo II inhibitor chemotherapy.