Endocrine Abstracts

Objective: SIR may occur in, 2 - 6% of ATA low risk and 67 - 75% of high risk DTC. Regarding locoregional disease, surgery is the optimal therapeutic modality if, the smallest dimension (sd) of the targeted node is ≥ 8 or 10 mm (central or lateral compartment). In the presence of, smaller nodes, contraindications or, patient’s unwillingness for reoperation, active surveillance or minimally invasive treatments (MIT), may be considered. The purpose of this study is to present 6 DTC cases with locoregional SIR and their response to RFA.

Methods: 6 patients (pts) with locoregional SIR following total thyroidectomy with central neck dissection were studied. Persistent or recurrent disease was defined as SIR ≤ 3 or ≥ 12 months (mos), respectively, after initial treatment. Clinical, histopathological, biochemical data and the therapeutic interventions were recorded.

Results: Pts were followed for 11 - 72 mos (median: 52.5), mean age at diagnosis: 42.2 years (range: 17 - 69). n = 5 were classified as ATA intermediate risk, n = 1 low risk. n= 2, presented aggressive variants (pt X: oncocytic widely invasive, pt Z: follicular with trabecular/insular/solid patterns). Lymphadenopathy was already present at diagnosis in n = 3, whereas in all but one radioiodine (RAI) was administrated with the whole-body scan (WBS) revealing minimal uptake in the thyroid bed. Persistent nodal disease was documented in n = 3 pts, mean size (sd): 4.88 mm (range: 4 - 6), volume (vol): 0.22 cm³ (range: 0.12 - 0.40) with serum suppressed thyroglobulin (TG): 3.56 - 3.80 ng/ml. RFA was performed and during a follow up of 3 - 33 mos (median: 12) a 75 - 93% (mean: 87.6) vol reduction was documented with subsequent decrease of TG ≤ 0.4 ng/ml. Recurrent disease was documented in n = 3 pts (including X, Z) 34 - 51 mos after RAI. In pt X, two consecutive locoregional recurrences were documented over a 12-mo period, prior to RFA; he was reoperated twice (with additional RAI) however, a third recurrence was documented 6 mos after previous surgery. Pt Z, due to rising Tg-antibodies and normal neck ultrasound, underwent second RAI, prior to RFA, 31 mos following thyroidectomy, with negative WBS; locoregional recurrence was documented 38 mos after thyroidectomy. Mean size of targeted lesions was (sd): 6.83 mm (range: 4.7 - 9.2) and vol: 0.42 cm³ (range: 0.20 - 0.90). RFA was performed and during a follow up of 3 - 15 mos (median: 9) a 67 - 95% (mean: 84.5) vol reduction was documented. In pt X, new recurrence, 3 mos following RFA, was documented; repeat RFA led to 40% vol reduction. n = 2 pts developed Horner syndrome secondary to RFA, which was completely resolved within 1-6 mos.

Conclusions: In DTC with locoregional SIR, RFA may lead to completion of the initial treatment, particularly in persistent disease. In recurrent disease, usually characterizing aggressive variants, RFA may locoregionally restrain disease progression. Larger studies, comparing different therapeutic modalities are needed, towards personalized treatment implementation especially, in intermediate and high-risk DTC.