Correlation between remnant thyroid gland I-131 uptake and serum thyroglobulin levels: can we rely on I-131 whole body scans?

BACKGROUND

I-131 treatment (RAI) decision relies heavily on serum thyroglobulin (Tg) levels, as higher Tg levels are assumed to be correlated with higher I-131 uptake. Tg elevation, negative iodine scintigraphy (TENIS) definition is becoming more clinically relevant as alternative treatment methods are available. This study examined the correlation between Tg levels with I-131 uptake in remnant thyroid gland to evaluate the reliability of serum Tg levels in predicting I-131 uptake.

METHODS

From March 2012 to July 2019, 281 papillary thyroid cancer patients treated with 150 mCi RAI were retrospectively enrolled. Early (2nd day) and Delayed (7th day) post-RAI whole-body scan (WBS) neck counts were correlated with clinical and pathologic findings. Patients with normal neck ultrasound and undetectable level of serum Tg (< 0.2 ng/mL) and thyroglobulin antibody (TgAb) (< 10 IU/mL) were defined as ablation success within 2 years after I-131 ablation.

RESULTS

Thyroid gland weight, tumor size and thyroiditis were independent factors of preoperative serum Tg levels. Serum off-Tg levels correlated with Early and Delayed WBS neck counts, and thyroiditis pathology contributed to lower neck counts in both Early and Delayed WBSs. In multivariable analysis, Delayed WBS neck count, serum off-Tg and off-TgAb were significant factors for predicting ablation success.

CONCLUSION

I-131 uptake and retention in remnant thyroid gland correlates with serum off-Tg levels, thyroiditis, and ablation success in thyroid cancer patients receiving high-dose I-131 therapy. Semi-quantitative I-131 analysis with Early and Delayed WBSs provides additional information in evaluating ablation success, with the potential application for metastasis treatment response evaluation.

Incidentally Detected Metachronous Malignancy in Patients of Papillary Carcinoma of Thyroid Posthigh-Dose Radioiodine Therapy

Thyroid cancer is one of the most common endocrine cancers. The most common histological subtypes are papillary and follicular variants; these are "differentiated thyroid cancers" and are associated with an excellent prognosis. The exact mechanism of thyroid cancer is not known. Several genetic alterations and environmental factors are found to be associated with this cancer. Patients with differentiated thyroid cancer are treated with postoperative radioactive iodine (RAI) therapy to ablate residual thyroid tissue and metastatic micro-foci. It is thought that after RAI, there is an increased risk of secondary malignancies such as lung, renal, and stomach cancer and lymphomas. However, the risk of secondary malignancy is not clear. They may be associated with genetic syndromes, environmental factors, and radiation exposure. The secondary malignancy may be detected incidentally during follow-up or present with signs and symptoms of that malignancy. There is no direct association between second malignancy and radiation exposure in I-131 therapies. We present a case series of five patients treated with high doses of I-131 for the remnant. The patients developed metachronous malignancies later in life.

Pros and cons of an aggressive initial treatment with surgery and radioiodine treatment in minimally invasive follicular thyroid carcinoma

BACKGROUND

Currently, surgery alone is the gold standard treatment for minimally invasive follicular thyroid cancer (mi-FTC).

CASE PRESENTATION

A case of a mi-FTC diagnosed in 1994 was treated with total thyroidectomy and radioiodine (RAI) ablation, according to the therapeutic algorithm used at that time. Nevertheless, he had a recurrence with distant metastasis after 24 years from the initial treatment.

CONCLUSION

Total thyroidectomy and RAI ablation might have delayed the development of distant metastasis but they were not sufficient to avoid disease recurrence. Certainly, remnant ablation simplified the follow-up and the monitoring of serum thyroglobulin allowed the early detection of the biochemical recurrence, but didn't change the outcome of the disease. Moreover, because of this early detection the patient was exposed to useless biochemical and imaging examinations. The aim of this report is to discuss the pros and cons of an aggressive treatment of a patient with mi-FTC.

Thyroidectomy for Papillary Thyroid Carcinoma

Papillary thyroid carcinoma is the most common endocrine malignancy and accounts for the overwhelming majority of thyroid carcinoma. This recent dramatic increase in incidence is almost exclusively attributed to the incidental detection of small papillary thyroid carcinoma or microcarcinoma. Surgical management of thyroid carcinoma has been evolving to avoid overtreating patients by adopting the appropriate risk-based approach including the recommendation of hemithyroidectomy for low-risk carcinoma, the avoidance of routine prophylactic central nodal dissections, a higher threshold in using postoperative radioiodine ablation after total thyroidectomy, and the active observation or surveillance of papillary microcarcinoma as a viable alternative option instead of immediate surgical treatment.

Risk of Diabetes in Patients with Long-Standing Graves' Disease: A Longitudinal Study

BACKGROUND

The detrimental effects of excessive thyroid hormone on glucose metabolism have been widely investigated. However, the risk of diabetes in patients with long-standing hyperthyroidism, especially according to treatment modality, remains uncertain, with few longitudinal studies.

METHODS

The risk of diabetes in patients with Graves' disease treated with antithyroid drugs (ATDs) for longer than the conventional duration (≥2 years) was compared with that in age-and sex-matched controls. The risk was further compared according to subsequent treatment modalities after a 24-month course of ATD: continuation of ATD (ATD group) vs. radioactive iodine ablation (RIA) group.

RESULTS

A total of 4,593 patients were included. Diabetes was diagnosed in 751 (16.3%) patients over a follow-up of 7.3 years. The hazard ratio (HR) for diabetes, after adjusting for various known risk factors, was 1.18 (95% confidence interval [CI], 1.10 to 1.28) in patients with hyperthyroidism. Among the treatment modality groups, the RIA group (n=102) had a higher risk of diabetes than the ATD group (n=4,491) with HR of 1.56 (95% CI, 1.01 to 2.42). Further, the risk of diabetes increased with an increase in the ATD treatment duration (P for trend=0.019).

CONCLUSION

The risk of diabetes was significantly higher in patients with long-standing Graves' disease than in the general population, especially in patients who underwent RIA and prolonged ATD treatment. Special attention to hyperglycemia during follow-up along with effective control of hyperthyroidism may be necessary to reduce the risk of diabetes in these patients.

Quality of life comparison in thyroxine hormone withdrawal versus triiodothyronine supplementation prior to radioiodine ablation in differentiated thyroid carcinoma: a prospective cohort study in the Indian population

BACKGROUND

Thyroid withdrawal in preparation for radioiodine ablation (RIA) may have a profound impact on health-related quality of life (HRQL). Cost implications and scheduling limit the use of recombinant TSH and triiodothyronine (T3) with its shorter half-life is a conceptually attractive alternative.

METHODS

Prospective cohort study design with patients having withdrawal of thyroxine (n = 37) or T3 supplementation (n = 33). HRQL was assessed using EORTC QLQ-C30, QLQ-H&N35 and modified Billewicz questionnaires. Time interval to achieve optimal TSH levels (at least 30 mIU/ml) prior to RIA was determined.

RESULTS

With the exception of emotional domain (QLQ-C30 p = 0.045), LT3 supplementation did not confer significant benefit when compared to LT4 withdrawal. Target serum TSH levels was achieved in 95% of patients by week 4 post thyroidectomy.

CONCLUSIONS

LT3 supplementation delivered equivocal benefit and therefore the alternate strategies to minimize the impact on HRQL of reduction in the duration of hypothyroidism in T4 withdrawal are suggested.

Lymphocyte-to-monocyte ratio prior to radioiodine ablation in low- and intermediate-risk, papillary thyroid cancer

PURPOSE

We aimed to investigate inflammation indices based on preablation hematological parameter of the lymphocyte-to-monocyte ratio (LMR) to predict the clinical outcome in papillary thyroid cancer (PTC) patients with low- and intermediate-risk stratification.

METHODS

This retrospective study analyzed 772 patients with low- and intermediate-risk PTC who underwent total thyroidectomy followed by radioiodine therapy between July 2005 and July 2009 with a median of 10 years. Kaplan-Meier statistics were used to test differences in recurrence-free survival (RFS) between groups based on the optimal cutoff point of biomarkers identified using receiver operating characteristic curves.

RESULTS

With an optimal cutoff point of 7.05, 215 patients (29.8%) were classified as having low LMR and 557 patients (71.2%) were classified as having high LMR. High LMR was significantly associated with a prolonged RFS (hazard ratio [HR]: 2.048, 95% confidence interval [CI]: 1.062-4.359, p = 0.001). Multivariate analysis showed that low LMR (HR = 2.035, 95% CI: 1.011-4.095, p = 0.012), tumor size over 2 cm (HR = 2.762, 95% CI: 1.303-5.852, p = 0.008), and high preablative simulated thyroglobulin level over 10 ng/ml (HR = 7.826, 95% CI: 2.353-26.033, p < 0.001) were independent prognostic markers for worse RFS in the enrolled PTC patients.

CONCLUSIONS

LMR at the time of radioiodine therapy has comparable predictor for the clinical outcome with both tumor size and preablative simulated thyroglobulin level in low- to intermediate-risk PTC patients.

Comparison of radioiodine ablation rates between low versus high dose, and according to the surgeon's expertise in the low-risk group of differentiated thyroid cancer

Radioiodine ablation following surgery is the accepted treatment for patients with differentiated thyroid cancer (DTC). Since that surgical volume and radioiodine dose can have impact on treatment outcome, we aimed to evaluate them on the treatment outcome of low-risk DTC patients. Low-risk DTC patients were classified into four groups, including (1) thyroidectomy was performed by thyroid surgeon and low-dose (1850 MBq [30 mCi]) radioiodine was administered (n = 17), (2) thyroidectomy was performed by thyroid surgeon and high-dose (3700 MBq [100 mCi]) radioiodine was administered (n = 10), (3) thyroidectomy was performed by general surgeon and low-dose radioiodine was administered (n = 22), and (4) thyroidectomy was performed by general surgeon and high-dose radioiodine was administered (n = 29). All patients were followed at least for 6 months and also for evaluation of treatment success, neck sonography, thyroid-stimulating hormone-off, thyroglobulin (Tg)-off, and anti-Tg-off tests were performed. Furthermore, two common radioiodine treatment-associated side effects, including dry mouth, and nausea/vomiting were assessed for all patients. Seventy-eight low-risk DTC patients (female: 70 [89.7%]; male: 8 [10.3%]) aged from 18 to 78 years old with mean of 41.96 ± 13.42 years were enrolled in this study. In total, the treatment was successful in 96.2% of patients. There was no significant difference in treatment success among groups (P > 0.05), while there was a significant association among administered activity and side effects. In low dose patients, only one patient complained from dry mouth; however, 11/39 patients who received high dose of iodine complained from dry mouth (P = 0.002). In addition, 9/39 high dose patients suffered from vomiting/nausea, while none of low-dose patients suffered from vomiting/nausea (P = 0.001). In low-risk DTC patients, surgical volume and amounts of radioiodine had no significant impact on treatment results; therefore, low dose radioiodine following thyroidectomy may be preferable to low-risk DTC patients to avoid side effects.

A Survey of UK Centres on Low Iodine Diet Recommendations prior to Radioiodine Ablation Therapy for Differentiated Thyroid Cancer

BACKGROUND

Guidelines suggest that a low iodine diet (LID) is advised prior to radioiodine ablation (RIA) for thyroid cancer. We aim to describe current practice regarding LID advice in the UK, determine uptake of the 2016 UK LID Working Group diet sheet and discover whether there are differences in practice.

METHODS

We used an online survey distributed between November 2018 and April 2019 to centres in the UK that administer ¹³¹I. We asked questions on whether a LID is advised, for how long, how advice is presented, whether and how compliance is measured and whether treatment is delayed if LID advice is not followed.

RESULTS

Fifty-six clinicians from 47 centres that carry out RIA for thyroid cancer responded. Forty-four centres (94%) advise a LID prior to RIA, the majority for 14 days (82%). Two-thirds of the centres use the UK LID Working Group diet sheet. Patients are told to resume normal eating when ¹³¹I is administered at 17 centres (39%), with 18 (41%) advising waiting for 24-48 h after administration. Most centres (95%) use only a simple question or do not assess compliance. Only 2 (5%) indicate that RIA would be delayed if someone said they had not followed LID advice.

CONCLUSIONS

UK practice regarding LID prior to RIA for thyroid cancer is consistent with current guidelines, but non-adherence does not usually delay RIA. The UK Low Iodine Diet Working Group diet sheet is widely recognised and used. Practice could be improved by centres working to harmonise advice on when to restart a normal diet.

Double Pyramidal Lobe of the Thyroid Gland a Rare Variation: Case Report

Knowledge of the variations of the pyramidal lobe of the thyroid is important for surgeons to perform complete resection of the functional thyroid tissue. Complete excision of the thyroid tissue surgery reduces the chances of recurrence in both the benign and the malignant diseases. It is important to remove all functioning thyroid tissue especially in the differentiated thyroid cancer so the postoperative radioiodine ablation is more effective and serum thyroglobulin acts as an efficient marker. We report a case of the double pyramidal lobe of thyroid gland in a woman of age 63 years with follicular thyroid cancer. Our literature search revealed only three documented cases of the double pyramidal lobe. Knowledge and recognition of such a rare variation is essential to perform safe and effective thyroid surgery.

Comparison between the different doses of radioactive iodine ablation prescribed in patients with intermediate-to-high-risk differentiated thyroid cancer

OBJECTIVE

This study aimed to compare the clinical outcomes of patients who received radioactive iodine (RAI) ablation after undergoing thyroidectomy for intermediate-to-high-risk differentiated thyroid carcinoma (DTC) according to the American Thyroid Association (ATA) criteria.

METHODS

We retrospectively examined patients who underwent RAI ablation for DTC after surgical resection without macroscopic residual lesions or metastatic lesions between December 2011 and August 2016. Among 147 patients who underwent RAI ablation, those whose initial pathological stages or RAI ablation results were unknown and whose distant metastases were confirmed during RAI ablation were excluded. Low-dose therapy was defined as administration of 1110 MBq of ¹³¹iodine (¹³¹I), while high-dose therapy referred to administration of 2960-3700 MBq of ¹³¹I. We defined initial success of RAI ablation as a serum thyroglobulin concentration of < 2.0 ng/mL without thyroid-stimulating hormone stimulation and disappearance of ¹³¹I uptake in the thyroid bed on ¹³¹I scintigraphy 6-12 months after RAI ablation. RAI ablation success rates were compared between the low-dose and high-dose groups using Fisher's exact test, and inverse probability of treatment weighting (IPTW) analysis was performed for adjusting potential biases.

RESULTS

Among the 119 patients examined in this study (39 men and 80 women), 79 were classified as having intermediate risk, while 40 were classified as having high risk based on the ATA guideline. Initial RAI ablation success was achieved in 50/68 (73.5%) patients from the low-dose group and in 36/51 patients (70.6%) from the high-dose group (p = 0.84). Moreover, IPTW analysis showed no significant difference between the low-dose and high-dose groups. However, the success rate tended to be superior in high-risk patients who received high-dose therapy (86.2%) than in those who received low-dose therapy (72.7%) (p = 0.37).

CONCLUSION

There was no significant difference in the RAI ablation success rate between the low-dose and high-dose groups involving patients with intermediate-to-high-risk DTC. However, high-dose RAI ablation may be recommended in high-risk patients.

A Rare Case of Thyrolipomatosis Presenting with Latent Hyperthyroidism

Goiter and hyperthyroidism are fairly common problems in the Indian population. We present a 49-year-old female who presented with thyroid swelling and suppressed thyroid-stimulating hormone. On evaluation, she was having latent hyperthyroidism with diffuse and soft thyroid swelling. During the evaluation for feasibility of radioiodine ablation, she was found to have thyrolipomatosis on computed tomography. She was counseled for total thyroidectomy and subsequently underwent the same with histopathology confirming the presence of fatty infiltration into the thyroid stroma.

Successful Treatment of Differentiated Thyroid Carcinoma with Transaxillary Robotic Surgery and Radioiodine: The First European Experience

OBJECTIVES

Transaxillary robotic thyroidectomy surgery (TARS) has been reported to be a safe approach in patients with differentiated thyroid carcinoma, and oncological responses are promising.

STUDY DESIGN

This study aimed to evaluate the oncological outcomes of TARS followed by radioiodine (RAI) therapy in patients with differentiated thyroid carcinoma. Between 2011 and 2016, patients treated for differentiated thyroid carcinoma by TARS in a single institution, followed by RAI, were retrospectively included. The oncological response was performed according to the 2015 American Thyroid Association (ATA) guidelines 6-12 months later and at the last available visit.

RESULTS

A total of 42 patients (30 females) were included, with a median tumor size of 20 mm (12 cases of N1a and 5 cases of N1b on initial pathology report). According to ATA classification of recurrence risk after surgery, 17 and 25 patients were classified as low and intermediate risk, respectively. After RAI, all patients had a normal posttherapeutic whole body scan (except 1 patient, who had pathological lymph node uptake), but no unusual uptake was seen. At the 6- to 12-month evaluation (n = 37), 24 patients had excellent response, 8 had indeterminate response, and 5 had incomplete response (2 biological and 3 structural); no distant metastasis was found. At the last evaluation (median follow-up 15.9 months), 35 patients had no evidence of disease and 1 patient had a structural incomplete response. In total, a second open surgery was necessary for 3 patients to treat persistent lymph nodes (all intermediate risk).

CONCLUSION

In this study, TARS followed by RAI therapy seems to be curative, even for patients with lymph node metastases, after good preoperative staging. More studies are required to confirm the findings.

Papillary thyroid cancer recurrence 43 Years following Total Thyroidectomy and radioactive iodine ablation: a case report

Background

Recurrent papillary thyroid carcinoma (PTC) beyond the first two decades of definitive treatment (i.e. total thyroidectomy and radioactive iodine ablation) is a rare occurrence.

Case presentation

We present a case of a 71-year old Caucasian female with a distant history of PTC treated with total thyroidectomy and radioactive iodine ablation who experienced recurrence of her disease 43 years following initial diagnosis and definitive treatment. She presented with palpable left-sided neck mass and subsequently underwent a level II, III, neck dissection and adjuvant iodine ablation. This case presents the latest recurrence in papillary thyroid cancer documented to date in the literature.

Conclusion

This case exemplifies the need for the head and neck surgeon, radiation oncologist, general practitioner and radiologist to consider new lateral neck mass as late-presenting recurrence of PTC until proven otherwise regardless of low recurrence rates beyond two decades from treatment and low prognostic risk scores.

Re-ablation I-131 activity does not predict treatment success in low- and intermediate-risk patients with differentiated thyroid carcinoma

The aim of this study was to evaluate the efficacy of different radioactive iodine (I-131) activities used for re-ablation, to compare various combinations of treatment activities, and to identify predictors of re-ablation failure in low- and intermediate-risk differentiated thyroid carcinoma (DTC) patients. The study included 128 consecutive low- and intermediate-risk patients with DTC with ablation failure after total thyroidectomy. Patient characteristics, T status, tumor size, lymph node involvement, postoperative remnant size on whole-body scintigraphy, serum thyroglobulin (Tg), thyroid-stimulating hormone (TSH), anti-Tg antibody (TgAb), and Tg/TSH ratio were analyzed as potential predictors of the re-ablation success. Re-ablation was successful in 113 out of 128 patients (88.3 %). Mean first I-131 activity was 2868 ± 914 MBq (77.5 ± 24.7 mCi) and mean second I-131 activity 3004 ± 699 MBq (81.2 ± 18.9 mCi). There was no association between the first, second, and cumulative activity with re-ablation treatment outcome. Treatment failure was associated with higher Tg levels prior to re-ablation (Tg2) (OR 1.16, 95 % CI 1.05-1.29, P = 0.003) and N1a status (OR 3.89, 95 % CI 1.13-13.41, P = 0.032). After excluding patients with positive-to-negative TgAb conversion, Tg2 level of 3.7 ng/mL predicted treatment failure with a sensitivity of 75.0 %, specificity of 80.5 %, and a negative predictive value of 97.1 %. Patients with positive-to-negative TgAb conversion had higher failure rates (OR 2.96, 95 % CI 0.94-9.29). Re-ablation success was high in all subgroups of patients and I-131 activity did not influence treatment outcome. Tg may serve as a good predictor of re-ablation failure. Patients with positive-to-negative TgAb conversion represent a specific group, in whom Tg level should not be used as a predictive marker of treatment outcome.

Preoperative contrast-enhanced computerized tomography should not delay radioiodine ablation in differentiated thyroid carcinoma patients

BACKGROUND

There is concern about potential interference of iodinated contrast used in contrast-enhanced computerized tomography (CECT) with radioiodine therapy in differentiated thyroid carcinoma (DTC). The aim of this study was to determine the effect of iodinated contrast on urinary iodine concentration (UIC) in patients having thyroidectomy compared with control groups without CECT and without thyroidectomy.

METHODS

This prospective control study consisted of 4 groups each comprising 32 patients. Group 1- DTC patients undergoing preoperative CECT, group 2- DTC patients not undergoing CECT, group 3- benign goiter patients undergoing preoperative CECT, and group 4- patients with non-thyroidal diseases undergoing preoperative CECT. Spot UIC before CECT, after surgery (5-7 d), and at follow-up (4-6 wk) were compared among the groups.

RESULTS

The median basal UIC levels were not significantly different between the four groups (232.2 versus 263.9 versus 268.2 versus 178.2 μg/L, respectively, P = 0.443). In contrast, groups having preoperative CECT had significantly higher UIC levels at discharge (924 versus 329 versus 776 versus 661 μg/L, respectively, P = 0.001). These differences became insignificant at follow-up (225 versus 252 versus 310 versus 275 μg/L, respectively, P = 0.505). Patients having follow-up UIC values above the conventional cut-off of clinically relevant iodine excess (>200 μg/L) also had significantly higher basal values than those having lower follow-up values (283.0 versus 181.7 μg/L; P = 0.037).

CONCLUSIONS

Irrespective of the fact whether a patient is thyroidectomized or not preoperative CECT using non-lipophilic contrast does not result in long-term iodine retention.

Controversy over radioiodine ablation in thyroid cancer: who benefits?

Recent studies have proposed that overdiagnosis is probably the principal cause of the increased incidence of thyroid cancer. The controversy around radioiodine ablation is complicated by the ever increasing numbers of small, low-risk thyroid cancers being diagnosed. This article examines the history and evolving epidemiology of the disease and treatment.

Preparation with recombinant humanized thyroid-stimulating hormone before radioiodine ablation after thyroidectomy: a systematic review

BACKGROUND

Standard treatment for differentiated thyroid cancer is thyroidectomy followed in selected cases by radioiodine ablation (RA). Recombinant humanized thyroid-stimulating hormone (rhTSH) is an exogenous source of tsh that can be administered to obviate the need for hormone withdrawal. In this systematic review, we analysed the evidence for the therapeutic use of (rhTSH for RA preparation.

METHOD

A systematic review of the MEDLINE and EMBASE databases from 1996 through January 2008 selected articles reporting randomized controlled trials, cohort studies, and retrospective studies published in English that compared ra using rhTSH with standard hormone withdrawal.

RESULTS AND INTERPRETATION

Stimulation by rhTSH is equivalent to thyroid hormone withdrawal in achieving ablation while avoiding detrimental symptoms of hypothyroidism and significantly lowering the whole-body radiation dose. Furthermore, rhTSH may be the only option for patients who either cannot raise endogenous tsh or who would be at risk from the morbidity of hypothyroidism. Based on the results of validated instruments of physical and mental performance, there is agreement that rhTSH maintains a better quality of life. Studies of cost-effectiveness found that rhTSH-prepared patients lost less time from work and required fewer encounters with health care providers.