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General Clinical Specialties: EndocrinologyAdvances in Management of Benign Endocrine Disorders |
1 Nuclear Medicine, University of Tuebingen, Tuebingen, Germany
359
Objectives: To investigate the effect of achieved dose and other prognostic factors on the outcome after radioiodine treatment (RIT) of toxic thyroid adenoma.
Methods: 563 patients underwent RIT for solitary (SA) or multiple (MA) toxic nodules or disseminated autonomous thyrotoxicosis (DA). Radioiodine uptake (RAIU) 24 and 48 h after 2 MBq Iodine-131, Tc-Uptake (TcTU), ultrasound, serum hormone levels as well as achieved doses were obtained for all pts. Planned target doses were: SA: 400 Gy, n=276; MA/DA 150 Gy, n=287. Subgroups of pts. were treated with lower planned target doses (SA: 200-300 Gy, n=83; MA/DA: 100-125 Gy, n=39). Outcome was estimated 3 (n=563) and 12 (n=276) month after RIT.
Results: RIT failed to cure thyrotoxicosis in 10.5% of pts. (SA: 9.5%; MA/DA: 12.5%). Achieved target doses demonstrate that 200 Gy (SA) or 110 Gy (MA/DA) were sufficient to cure 80 % of pts. Considerably higher doses were necessary for better cure rates (for 90%: 300 Gy [+50%, SA] and 240 Gy [+115%, MA/DA]; for 95%: >400 Gy [SA, MA/DA]). Other prognostic factors were: TcTU, RAIU, achieved target dose, total thyroid volume, target volume, antithyroid drugs (all p < 0.01). Multivariate analysis (MuStat) identified target volume, TcTU and achieved target dose as strongest factors.
Conclusions: Most pts. can be cured (80%) with comparatively low target doses (SA: 200 Gy, MA/DA: 110 Gy). Much higher doses will be necessary for better cure rates which in turn points to a subgroup of patients for which the current estimation of treatment activity should be modified. Since this applies especially to MA/DA pts (target volume = thyroid volume) correction for autonomous tissue volume might be useful.
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