Macroscopic invasion of tumor into the perithyroidal soft tissues (gross extrathyroidal extension)Incomplete tumor resectionDistant metastasesPostoperative serum thyroglobulin suggestive of distant metastasesPathologic N1 with any metastatic lymph node ≥3 in largest dimension*Follicular thyroid cancer with extensive vascular invasion (>4 foci of vascular invasion)*. This evidence concerns the gene TG and thyroid cancer.