TERT and thyroid cancer, nonmedullary, 2: Our group showed, in a study of 60 malignant tumors (PTC, FVPTC, FTC, and HCC) and 73 benign lesions, that malignant tumors showed a higher amount of the full-length isoform than the inactive TERT isoforms, while conversely, the benign tumors showed higher levels of the deletion isoforms (61).