Differenziertes Schilddrüsenkarzinom - Konzepte nuklearmedizinischer Therapie und Nachsorge

The primary goal of radioiodine therapy with 131-iodine (131I) in differentiated thyroid cancer is the elimination of postoperative residual thyroid tissue to optimize follow-up. Merely in papillary microcarcinoma usually no radioiodine therapy is performed. Moreover, radioiodine therapy can also be performed for the treatment of ioidide accumulating local recurrences and metastases. The applied activities of radioactive 131131I mainly are standardised but can be adapted depending on the initial stage. Both in radioiodine therapy and in posttherapeutic 131I-whole body-scintigraphy, the stimulation of TSH-level is necessary to optimize the uptake of radioactive iodine in residual thyroid tissue and tumour cells. The stimulation of TSH can be achieved both by application of recombinant TSH (exogenous TSH-stimulation) and by discontinuing levothyroxine (endogenous TSH-stimulation). In posttherapeutic levothyroxine substitution meanwhile not basically a complete TSH-suppression, but a risk-adapted metabolic adjustment corresponding to the initial TNM-stadium is recommended. Routine follow-up examinations comprise a diagnostic 131I-whole body-scintigraphy 3–6 months after thyreoablative radioiodine therapy, periodical cervical sonography, control of tumour marker thyreoglobuline (TG) and metabolic adjustment with levothyroxine by measuring fT3, fT4 and TSH. About 4 % of all patients additionally develop permanent hypoparathyreoidism after total thyreoidectomy which makes the substitution of calcium and activated vitamin D3 necessary. If a computed tomography is required, it must be perfomed native.