Patients were excluded when they met the exclusion criteria: 1070 did not receive total thyroidectomy, 182 were not DTC, 768 did not have TgAb data or had positive results of TgAb, 312 did not reach undetectable Tg during the first 2 years to initial therapy, 26 had distant metastasis upon the diagnosis of thyroid cancer and 1612 did not have ≥ 3 undetectable Tg levels after initial treatment. This evidence concerns the gene TG and thyroid cancer.