Abstract

DEGROSSI, EB et al. Radioiodine Ablation in Patients with Low Risk Papillary Thyroid Carcinoma. Comparison of Three Methods to Prepare the Patient. Evolution of Illness in Follow-Up. Rev. argent. endocrinol. metab. [online]. 2013, vol.50, n.4, pp.211-218. ISSN 1851-3034.

Background: Almost total thyroidectomy and ablation (A) are the primary treatment of differentiated thyroid carcinoma^(1-16). In recent years the use of ablation in low risk papillary thyroid carcinoma (LR-PTC) has become controversial(17,18). Objectives: a) to confirm that the method of TRH-TSH stimulation -TRH-ST(15,16) is adequate to increase serum TSH in a short time. Material and Methods: Ablation was carried out in 117 patients with LR-PTC. In 34 patients (G-I) TRH-St method was utilized starting on day 8 after surgery with TRH stimulation on days 8, 10, 12 and 13 and applying ablation on day 13. In 54 patients (G-II) ablation was performed by delaying the onset of thyroid hormone treatment for 4-5 weeks, leading the patient to hypothyroidism. In the remaining 29 patients (G-III) rhTSH was utilized to increase TSH. Patients were followed up for 1.5 to 6.2 years (mean 3.6 years) and were classified according to the results observed during follow-up as free of disease (Fof D) or with relapse or metastasis (RorM). Results: G-I: TSH 109±106 mU/L (range 35-360); Tg 7.9 ± 6.1 ng/mL; RorM 3.23 %. G-II: TSH 82 ± 76 mU/L, range 31-220; Tg 5.8 ± 6.9 ng/mL; RorM 4 % .G-III: TSH 138 ± 32 mU/L. range 82-240, Tg 3.9 ± 2.2 ng/mL, RorM 4 %. The Tg values were those found under stimulated TSH previous ablation. No statistically significant differences were found in follow-up, TSH values were higher in G-III, p<005. Discussion: similar results were observed with the 3 methods used. TRH-ST is adequate to obtain ablation with a very short time of thyroid hormone withdrawal after surgery. At follow-up, 3.74 % of patients were erroneously incorporated to the group of LR, in agreement with the results presented by Tutttle et al(19). In patients with no radioiodine ablation the cases with relapses or metastasis increased with time and the incidence was estimated at more than 15 % according to Mazzaferri et al^{(5, 6)} and our own experience. We considered that in patients with LR-PTC ablation is very important not only according to physical and psychological reasons but also for the cost-benefit ratio in the patient’s health care. For these reasons, we believe that as long as the criteria to consider a patient as low risk are not changed, thyroid ablation should be performed by modifying the radioiodine activity used for that purpose. Conclusion: Our objective has been accomplished.

Keywords : Low risk; Papillary thyroid cancer; Ablation.

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