To date, studies in this regard are still scant; however, it was already demonstrated that the expression of the estrogen receptors-α and -β, progesterone receptor, and the androgen receptor was higher in PTMCs than in non-tumorous thyroid tissue [29] and that both testosterone and oestradiol have a specific effect on the proliferation of human thyroid papillary carcinoma cell lines independent of TSH action [30, 31]. This evidence concerns the gene ESR1 and thyroid gland papillary carcinoma.