OBJECTIVE: To compare the efficacy of low and moderate 131I activities in low-risk differentiated thyroid carcinoma (DTC) patients requiring postoperative thyroid remnant ablation in a real-world clinical setting.
METHODS: We retrospectively reviewed the records of 299 low-risk DTC patients (pT1-T2, Nx(0) Mx) who had undergone (near)-total thyroidectomy followed by 131I therapy, using either low (1.1 GBq) or moderate (2.2 GBq) radioiodine activities. The response to initial treatments was evaluated after 8-12 months, and patient responses were classified according to the 2015 American Thyroid Association guidelines.
RESULTS: An excellent response was observed in 274/299 (91.6%) patients, specifically, in 119/139 (85.6%) and 155/160 (96.9%) patients treated with low and moderate 131I activities, respectively (p = 0.029). A biochemically indeterminate or incomplete response was observed in seventeen (22.2%) patients treated with low 131I activities and three (1.8%) patients treated with moderate 131I activities (p = 0.001). Finally, five patients showed an incomplete structural response, among which three and two received low and moderate 131I activities, respectively (p = 0.654).
CONCLUSIONS: When 131I ablation is indicated, we encourage the use of moderate instead of low activities, in order to reach an excellent response in a significantly larger proportion of patients, including patients with the unexpected persistence of the disease.

The 2015 American Thyroid Association (ATA) guidelines called for significantly more selective 131I therapy in patients with low-risk differentiated thyroid cancer (DTC). We hypothesized that application of these guidelines would significantly reduce the 131I activity utilized by an academic tertiary hospital in Jordan.
All DTC patients managed at Jordan University Hospital (JUH) between 1/2009 and 6/2019 were classified according to the 2015 ATA risk category and 131I activity was assigned accordingly. The actual 131I activity administered was compared with that recommended by the 2015 ATA guidelines.
In total, 135/182 DTC patients (74.2%) managed at JUH underwent 131I therapy. Of those, 58 (43%) had ATA low-, 58 (43%) intermediate-, and 19 (14%) high-risk disease. The low-, intermediate-, and high-risk DTC patients received an average (±SD) initial 131I activity of 3.53 ± 0.95, 4.40 ± 1.49, and 5.06 ± 2.52 GBq, respectively. Withholding 131I therapy altogether in the 2015 ATA low-risk patients would result in decreasing the 131I activity in the overall patient population by 37%. Withholding 131I therapy only in low-risk papillary thyroid microcarcinomas while administering 1.11 GBq of 131I to other low-risk patients would result in 28% reduction of 131I.
This study demonstrates a significant reduction in 131I therapeutic activity that would be given to DTC patients in an academic tertiary setting in Jordan, following acceptance of the 2015 ATA recommendations. Institutions that adopted the 2015 ATA guidance should measure outcomes in comparison to their historical controls and report those findings, while long-term results of randomized controlled trials are forthcoming.

OBJECTIVE: To determine the frequency of levothyroxine (LT4) supplementation after therapeutic lobectomy for low-risk differentiated thyroid cancer (DTC).
METHODS: This retrospective cohort study enrolled adult patients with low-risk DTC confirmed using surgical pathology who underwent therapeutic lobectomy at a single institution from January 2016 through May 2020. The outcome measures were postoperative serum thyroid-stimulating hormone (TSH) levels and the initiation of LT4. The predictors of a postoperative TSH level of >2 mU/L and initiation of LT4 were evaluated using Cox proportional hazards models.
RESULTS: Postoperative TSH levels were available for 115 patients (91%), of whom 97 (84%) had TSH levels >2 mU/L after thyroid lobectomy. Over a median follow-up of 2.6 years, a postoperative TSH level of >2 mU/L was associated with older age (median 52 vs 37 years; P = .01), higher preoperative TSH level (1.7 vs 0.85 mU/L; P < .001), and primary tumor size of <1 cm (38% vs 11%, P = .03). Multivariate analysis revealed that only preoperative TSH level was an independent predictor of a postoperative TSH level of >2 mU/L (hazard ratio [HR] 1.53, P = .003). Among patients with a postoperative TSH level of >2 mU/L, 66 (68%) were started on LT4 at a median of 74 days (interquartile range 41-126) after lobectomy, with 51 (77%) undergoing at least 1 subsequent dose adjustment to maintain compliance with current guidelines.
CONCLUSIONS: More than 80% of the patients who underwent therapeutic lobectomy for DTC developed TSH levels that were elevated beyond the recommended range, and most of these patients were prescribed LT4 soon after the surgery.

OBJECTIVE: We determined the reasons for radioiodine thyroid remnant ablation, and the procedure\'s necessity based on postsurgical remnant size, in patients with putatively \"low-intermediate-risk\" differentiated thyroid carcinoma (DTC). We identified key clinicopathological, treatment and remnant characteristics, and factors associated with remnant size in 336 patients with pT1/2, M0 DTC ablated during the period September 2010 to October 2013 at one Cypriot or one Greek referral centre.
METHODS: Clinicopathological/treatment characteristics were compiled from charts. Experienced nuclear medicine physicians rated the numbers/intensities of uptake foci in the thyroid bed on postablation planar scintigrams using scales of 0-4 points and 0-3 points, respectively. The product of these scores was taken as the \"remnant score\" that ranged from 0 (no remnant) to 12 (multiple remnants, intense uptake).
RESULTS: DTC was predominantly papillary. The median [25th-75th percentile] longest primary tumour diameter was 1.0 cm [0.7-1.5 cm]. Despite favourable histotypes and primary tumour classifications, patients often had preablation characteristics suggesting elevated or uncertain risk: 31.0% of patients (104 of 336) had primary tumour multifocality, 22.0% (74) had confirmed cervical lymph node metastases, 37.2% (125) had unknown nodal status, and 38.1% (128) had antithyroglobulin antibody seropositivity. The median [25th-75th percentile] remnant score was 4 [2-6]; 39.9% of patients (134 of 336) had scores ≥6. For the entire cohort, T or N stages (r ≤ 0.174, P ≤ 0.05) correlated positively with the remnant score in a univariate Spearman analysis. The numbers of patients referred by the surgeon, cervical lymph nodes excised and metastatic nodes excised correlated negatively (r ≤ 0.243, P ≤ 0.038) with the remnant score, and the first two factors independently predicted the remnant score (P ≤ 0.037) in a multivariate analysis.
CONCLUSIONS: Patients with putatively \"low-intermediate-risk\" DTC frequently had disease characteristics denoting high or uncertain risk, suggesting that \"selective\" radioiodine ablation in such patients may seldom be applicable outside international centres of excellence. Proxies for surgeon experience and surgical completeness correlated with remnant number/uptake intensity and may aid ablation-related decision-making.