In those patients who achieve an excellent response to therapy (no clinical evidence of tumor, no imaging evidence of tumor, and suppressed Tg <0.2 ng/mL or stimulated Tg <1 ng/mL with negative antibodies), repeated stimulation testing may not be necessary, and the interval between subsequent Tg measurements may be lengthened to 12–24 months. This evidence concerns the gene TG and neoplasm.