5 Years Follow Up Of Thyroglobulin (Tg), Thyroglobulin Antibodies (Tgab) And Neck Ultrasound (Nus) In Patients With Papillary Thyroid Microcarcinoma (Mptc) Treated With Total Thyroidectomy But Not Ablated With 131I

Background: Serum thyroglobulin (Tg) and Thyroglobulin Antibodies (TgAb) assays are considered as the cornerstone for the post-operative management of patients with differentiated thyroid cancer (DTC) after the initial treatment. Less is known about the significance of this parameters in pts who do not perform radioiodine ablation (RRA) as in case of mPTC. Materials and Methods: We retrospectively evaluated epidemiological, clinical and pathological data of 293 consecutive patients with mPTC, surgically treated at our Department (2005–2012). We included [T1a] pts that had at least three determinations of serum Tg, TgAb and nUS. The aim of our study was to clarify the significance of the Tg and TgAb trends during the follow-up. Results: We divided our pts in group A (238 pts) (TgAb <20 mU/l) and group B (55 pts) (TgAb >20 mU/l) and we analyzed the Tg and TgAb course during the follow-up (mean 5.1-median 5 yrs). In Group A, 159/238 (66.8%) pts [A1] had Tg <0.5 ng/ml at the first control, 42/238 (17.65%) pts [A2] had a Tg between 0.5–1 ng/ml and 37/238 (15.55%) pts [A3] had Tg >1 ng/ml; at the end of follow up only in 35/238 (14.7%) pts, Tg was >1 ng/ml. In all pts neck US was negative for lymphnode metastases. In all pts of group B there was a decrease >20% of TgAb levels and nUS was negative. Basal TSH (bTSH) in [A1] (mean 0.93 ± 1.95 μU/ml) was significantly lower of final TSH (fTSH) (mean 1.36 ± 6.05 μU/ml) (p < 0.05), as far as in [A3], bTSH (mean 3.73 ± 9.74 μU/ml), was significantly higher that fTSH (mean 0.78 ± 0.77 μU/ml) (p < 0.01). Conclusion: 1) Almost 70% of our mPTC pts were ‘surgically ablated’ since their Tg was <0.5 ng/ml, three months after surgery; 2) After 5 years follow-up about 15% of pts had Tg >1 ng/ml without any evidence of structural disease in the neck; 3) All cases with positive TgAb showed a decrease of TgAb titer; 4) The 5 yrs follow-up of mPTC not submitted to RRA showed a very good outcome and the absence of recurrence: these pts can be monitored at longer intervals.