Dose Of RAI Research Articles

Nasolacrimal Duct Obstruction Following Radioactive Iodine: An Update on Counseling Recommendations for Thyroid Cancer Survivors

ObjectiveRadioactive iodine (RAI) treatment for thyroid carcinoma may induce nasolacrimal duct obstruction. Evidence-based recommendations regarding nasolacrimal screening and prophylactic management in thyroid cancer survivors are lacking. MethodsA case control study of patients treated with radioactive iodine for thyroid carcinoma was performed, comparing those who developed symptomatic nasolacrimal duct obstruction (group 1) to age- and gender-matched controls who did not develop nasolacrimal duct obstruction (group 2), to identify risk factors. ResultsFifty patients with history of RAI treatment for thyroid carcinoma were reviewed, including 25 patients who subsequently developed epiphora and were diagnosed with nasolacrimal duct obstruction, and 25 age- and gender-matched RAI-treated patients who did not develop nasolacrimal duct obstruction. The mean cumulative RAI dose was 223.4 mCi (8.27 Gbq) for group 1 and 121.4 mCi (4.49 Gbq) for group 2 (P = .0092). The mean initial treatment dose was 128.9 mCi (4.77 Gbq) and 100.0 mCi (3.70 Gbq) for the 2 groups, respectively (P = .0317). The mean number of RAI treatment sessions in patients who developed nasolacrimal duct obstruction was 1.48 (range 1-3), compared to 1.16 (range 1-2) in the group that did not (P = .0387). ConclusionsHigher initial and cumulative treatment dose of RAI, and multiple treatment sessions, increased likelihood of subsequent development of nasolacrimal duct obstruction. We recommend increased counseling and screening of thyroid cancer survivors undergoing RAI for thyroid carcinoma at lower doses than previously indicated, particularly in those who undergo multiple treatment sessions.

Predictors of response to Radioactive Iodine Therapy in Intermediate and high risk patients with papillary thyroid carcinoma

BackgroundRadioactive iodine (RAI) therapy is the standard treatment approach after total thyroidectomy in patients with papillary thyroid carcinoma (PTC). We aimed to identify predictive factors of response to the treatment in intermediate and high-risk patients with PTC. In addition, the impact of multiple RAI treatments was explored.MethodsIn a 3-year retrospective study, data from intermediate and high-risk patients with PTC who received RAI therapy following total thyroidectomy, were analyzed by the end of year-one and year-three. Demographic data, tumor size, capsular/vascular invasion, extrathyroidal extension, local or distant metastasis, initial dose and cumulative dose of RAI, serum thyroglobulin(Tg), antithyroglobulin antibody(TgAb), and imaging findings were investigated. Patients with an excellent response to a single dose of RAI treatment, after three years of follow-up were classified as the “Responder group”. Excellent response was defined as stimulated serum Tg less than 1 ng/ml, or unstimulated serum Tg less than 0.2 ng/ml in TgAb-negative patients with negative imaging scans.Results333 patient records with a complete data set were analyzed in this study. After three years of initial treatment, 271 patients were non-responders (NR) and 62 were responders (R). At baseline, the median pre-ablation serum Tg level was 5.7 ng/ml in the NR group, and 1.25 ng/ml in the R group (P < 0.001). TSH-Stimulated serum Tg greater than 15.7 ng/ml, was associated with response failure even after multiple RAI therapy, AUC: 0.717(0.660–0.774), sensitivity: 52.5%, specificity: 89.47%, P < 0.001. On the other hand, multiple RAI therapy was associated with excellent response in 16.2% of the patients. The chance of ER was decreased by 74% if initial post-operation ultrasound imaging confirmed the presence of locoregional involvement, OR 0.26, (95% CI: 0.12–0.55), P < 0.001.ConclusionStimulated serum Tg and locoregional involvement after total thyroidectomy are predictive factors of non-response to RAI therapy in intermediate and high-risk patients with PTC. In addition, a minority of patients achieve excellent response after multiple RAI therapy.

The Presence of Anti-TPO Antibodies Increase the Likelihood of Post-I131 Hypothyroidism.

The use of radioactive iodine in the treatment of hyperthyroidism is common practice. However, a standardized treatment protocol with regard to radioactive iodine treatment (RAI) remains subject to discussion. We retrospectively analyzed 100 patient records. Patient diagnosis, age, gender, body mass index (BMI), dose of radioactive iodine, thyroid size, the 24 h radioiodine uptake (24 h RAIU) and protein bound iodine (PBI) were deducted, as well as the use of antithyroid drugs prior to RAI. Biochemical parameters were obtained, such as TSH, fT4, fT3, Anti-TPO, Anti-TG antibodies and thyroid stimulating antibodies. After 5 years of follow-up, 46% of the patients proved to be hypothyroid, whereas 8% of the patients were not cured after one dose of RAI. One year after RAI, a larger proportion of patients with a toxic nodule developed hypothyroidism compared to patients with a multinodular goiter (MNG) (44.2% vs. 21.2%). Radioactive iodine dose, PBI, RAIU, BMI, size of the thyroid gland, diagnosis, age and TPO-antibodies showed statistically significant differences in the development of hypothyroidism. Furthermore, thiamazole pretherapy was shown to be a predictor of hypothyroidism, as well as a high PBI value, exhibiting a positive predictive value of 85.2% when the PBI exceeded 0.16. We suggest a standardized measurement of TPO-Ab's to further determine their role in the development of hypothyroidism after RAI. The empirical dosing regimen was very effective, illustrating a 92% cure rate after 1 dose.

SAT554 Follicular Variant of PTCA Initially Presenting with Widespread Metastases

Abstract Disclosure: N.N. Bisquera: None. R.C. Mirasol: None. Background: Papillary thyroid carcinoma accounts for most cases of thyroid cancer. Most cases of PTC have a good prognosis and low incidence of metastases. The follicular variant is the most common variant. First described in the 1960’s, the understanding of FV-PTC began to evolve with molecular profiling demonstrating a similarity with FTC, and clinical behavior profiling showing that a subtype may behave like PTC with a propensity for lymph node metastases. We are presented with an unusual case of an infiltrative FV-PTC presenting with widespread multiple metastases on diagnosis. Clinical Case: A 64-year-old female, presented with 1-year history of a slowly enlarging mass on the left mandible, which was also associated with an enlarging anterior neck mass. She had no constitutional symptoms and had previously been in good health. On examination, there was a 7x8x3 cm hard, fixed left mandibular mass. There was also a palpable right thyroid nodule measuring 2.5x2 cm. There was no difficulty in swallowing or breathing, but she had some difficulty in eating due to trismus. There were no associated symptoms of hypo/hyperthyroidism. Investigations revealed a euthyroid status. CT scan showed a solid lobulated heterogeneously enhancing mass measuring 4.2x5.1x5.2cm on the body and angle of the left mandible. Ultrasound showed multiple thyroid nodules, the largest - a mixed cystic and solid mass measuring 2.9 x 2.7 x 2.17 cm on the right thyroid lobe, for which FNA was performed. Histopathology showed benign follicular nodules. Incision biopsy of the mandibular mass showed presence of thyroid tissue. Further imaging showed metastases to the left frontal, parietal bone, T7 vertebra, and bilateral lungs. The case was discussed in a multi-disciplinary tumor board meeting. With a pre-operative diagnosis of a primary thyroid malignancy, the patient then underwent a total thyroidectomy with segmental mandibulectomy. Post-operative histopathology showed a metastatic multifocal infiltrative follicular variant of PTC. RAI was administered post-surgery, and she was started on suppressive thyroxine therapy. Steroids were given during RAI, with no untoward events post treatment. Post-ablative whole body scanning revealed increased tracer uptake in multiple areas: left frontal and parietal bone, bilateral thyroidal beds, left supraclavicular lymph node, the sternomanubrial junction, bilateral lung lobes, right humeral head and T7 vertebra. Further doses of RAI was planned and she is currently maintained on suppressive thyroxine therapy. Conclusion: Diagnosis of FV-PTC may be a greater challenge than conventional forms because of possible false-negative results on cytology. The infiltrative subtype has greater metastatic potential and higher recurrence rates. Multidisciplinary team management and careful preparation prior to treatment with RAI is indicated in these cases. Presentation Date: Saturday, June 17, 2023

SAT510 I-131 Therapy with Dosimetry for Advanced Thyroid Carcinoma: Recombinant TSH vs Thyroid Hormone Withdrawal

Abstract Disclosure: D. Awad: None. J. Hamsa: None. A. Fingeret: None. C. Johnson: None. F. Rutar: None. C. Carson: None. A. Kotwal: None. A. Patel: None. A. Thornburg: None. W.S. Goldner: None. Background: Dosimetry can be used to calculate an optimal and safe dose of Iodine-131 (I-131) for treatment of advanced differentiated thyroid cancer (DTC). Thyroid hormone withdrawal (THW) is the preferred method of TSH elevation for I-131 therapy with dosimetry. At our institution, Recombinant TSH (RhTSH) is used in patients in whom prolonged hypothyroidism is deemed clinically unsafe or cannot tolerate THW. We aim to evaluate if RhTSH and THW are equivalent methods of preparation for I-131 therapy using dosimetry (I-131D). Methods: This is a single institution retrospective cohort study evaluating all patients who received I-131D from 2010-2022. Demographic, clinical variables were assessed and dosimetric calculations were obtained. Statistical analysis was performed with Mann Whitney U, Kruskal Wallis, Chi-squared and Fisher’s exact testing. Results: Fifty-one unique patients were included with a total of fifty-five I-131D treatments, with 55% being female. Median (IQR) age at time of treatment was 60.3 years (42.8-70.4), and BMI kg/m2 was 29.3 (24-33.8). Of these patients 13% were stage I, 18.5% stage II, and 68.5% stage III/IV AJCC 7th ed. Sixty percent underwent THW and 40% received RhTSH. Gamma camera and blood activity measurements, at several time points following the pre-therapeutic I-131 dose, were taken to calculate the residence times and effective half-lives in whole body and blood. All patients demonstrated a monophasic elimination of I-131 activity in both the whole body and blood. Patients receiving RhTSH exhibited a slower elimination of the I-131 in the whole body than THW patients (effective half-life of 22 hrs vs 17 hrs) resulting in a higher fraction of I-131 activity remaining in the whole body 48 hours post-dose (25% vs 16%, p= 0.025). The effective half-life in the blood was also higher in the RhTSH group (p=0.025) resulting in a higher amount of activity remaining in the blood. As a result, the median (IQR) RAI dose was lower for those who received RhTSH (187.5 mCi (167-198)) vs those who underwent THW (260 mCi (202-306)) (p&amp;lt;0.001). As expected, TSH at the time of treatment was higher in the RhTSH group (p=0.0038). Thyroglobulin was higher at the time of treatment in the RhTSH group (p=0.031), but thyroglobulin drop at three months was not statistically different (p=0.0682) between groups. Conclusion: RhTSH administration is non-inferior to THW as a method of TSH elevation and preparation for I-131D for patients with advanced DTC. RhTSH, in comparison to THW, results in a significantly longer half-life in the whole-body and blood resulting in a lower calculated RAI dose. More studies are needed to confirm these findings. Presentation Date: Saturday, June 17, 2023

Outcomes of Radioactive Iodine (131I) Therapy among Hyperthyroid patients.

The present study aimed to assess the thyroid outcomes six-months after radioactive Iodine-131 therapy (RIT) among hyperthyroid patients and identify the factors associated with them. This retrospective observational study was conducted at the department of Nuclear Medicine and Molecular Imaging, Northwest General Hospital & Research Centre during 2013 to 2019. For the study purpose, the thyroid outcomes of 153 hyperthyroid patients were studied retrospectively for six months after RIT. The data was obtained from the medical records. Patient baseline characteristics, clinical features, laboratory investigations, results of thyroid imaging, and therapeutic investigations were acquired and recorded in a structured questionnaire. Out of the 153 screened records of hyperthyroid patients, 19.6% became euthyroid, 9.2% remained hyperthyroid, and 25.5% developed hypothyroidism after six months of RIT. The observed remission rate by the end of six months was 80.95%. Three months post-RIT, gender and RAI doses had a significant effect on thyroid function. The frequency of hypothyroidism was higher among those treated with an RAI dose of ≤ 20 mCi (83.0%) than those treated with a higher dose > 20 mCi (17%). Moreover, most patients receiving > 20 mCi radioiodine became euthyroid (64.5%). Similar outcomes were observed after six months of the therapy, except gender was replaced by etiologies of hyperthyroidism (p=0.009). Radioactive iodine (131-I) therapy is effective for the treatment of hyperthyroidism. However, the appropriate dose is still debatable, as there was a high incidence of hypothyroidism post-therapy.

The effect of radioiodine therapy on blood cell count in patients with differentiated thyroid cancer.

This study aimed to investigate the long-term effects of radioiodine treatment (RAI) on blood cell counts in patients with differentiated thyroid cancer (DTC) and to describe the characteristics of patients at high risk for blood cell count abnormalities. The study included patients with DTC who underwent RAI treatment between 2007 and 2017. Patients with regular complete blood counts for at least 5years were included, while those with diseases or treatments that could influence blood count parameters were excluded. Blood cell count abnormalities were defined according to the Common Terminology Criteria for Adverse Events version 5.0, and factors influencing these abnormalities were examined. A total of 225 patients were analyzed. The mean age at diagnosis was 45.8 ± 13.9years, and 76.5% of patients were female. In the first year after RAI, leukocyte, neutrophil, and lymphocyte counts were significantly reduced compared with baseline values. The leukocyte and neutrophil counts returned to baseline values by the third year, while the decrease in lymphocytes continued until the fifth year. Blood cell count abnormalities developed in 16 patients (7.1%) within the first year after RAI. Risk factors for blood cell count abnormalities within the first year after RAI included male sex, older age, T4, N1, and M1 disease, as well as higher RAI doses. In logistic regression analysis, only RAI dose remained independently associated with blood cell count abnormalities. These results suggest an association between RAI dose and blood cell count abnormalities, characterized by mild lymphopenia, and indicate that the risk of mild lymphopenia persists over time. Careful consideration should be given when planning high-dose RAI for patients at a high risk of blood cell count abnormalities, such as males with metastatic disease and of advanced age.

Differentiated thyroid cancer: effect on quality of life, depression, and anxiety.

Thyroid cancer is the most common endocrine cancer, the lifelong risk for which is approximately 1%. Despite favorable prognosis and well-tolerated treatment modalities, numerous studies have shown that thyroid cancer survivors have impaired health-related quality of life (HRQoL). Patients are also more frequently affected by depression and anxiety. We aimed to evaluate HRQoL, depression, and anxiety status in female patients with DTC. We compared HRQoL, depression, and anxiety status in 114 female thyroid cancer survivors with 110 healthy subjects via a cross-sectional design. For this purpose, we utilized short-form 36 (SF-36), Beck Depression Inventory (BDI), and Beck Anxiety Inventory (BAI). The majority of the patients (82%) were stage I. Fifty-seven patients (51%) received radioiodine treatment. Regarding HRQoL, depression, and anxiety between groups, thyroid cancer survivors did worse on every aspect of SF-36 than the control group (p < 0.05). Thyroid cancer survivors had higher BDI and BAI scores (p < 0.05). In those receiving RAI, the dose of RAI, lymph node dissection, and tumor stage did not affect SF-36, depression, and anxiety scores. Duration since diagnosis also did not affect results. Our study further confirms the observation that survivors of DTC have impaired HRQoL. Furthermore, they are more likely to suffer from anxiety and depression.

LBODP096 High Failure Rate Of Radioactive Iodine-131 (Rai) Therapy For The Treatment Of Grave's Disease And Toxic Multinodular Goiter In An Urban Municipal Hospital Clinic

Abstract Background Radioactive iodine-131 (RAI) therapy is used to treat hyperthyroidism secondary to toxic multinodular goiter (TMNG) and Graves’ Disease (GD). The treatment failure (TF) rate for RAI as reported in previous studies is 8-16% (1). Most patients respond to RAI with normalization of thyroid function tests and improvement of clinical symptoms within 4–8weeks. Previous studies also report higher TF rates amongst Black patients (2), but due to the low number of Blacks included in the study, identification of factors related to higher TF rates was difficult. Study Purpose: Determine treatment failure rates in patients who underwent RAI treatment for hyperthyroidism and characteristics related to Treatment Failure. Methods This is a retrospective study that included patients treated with RAI for either TMNG or GD from 2014-2021 at an urban hospital. Patients with thyroid cancer, less than 18 years, or toxic adenoma were excluded. TF was defined as persistent hyperthyroidism 6 months after RAI. Remission was defined as euthyroid or hypothyroid state off of anti-thyroid hormones 6 months after RAI. Factors evaluated included age at RAI, gender, race, cause of hyperthyroidism, percentage uptake in pretreatment scan, peak Ft4 / Ft3 pre-treatment, RAI dose, and treatment with methimazole post RAI. Comparison of TF to those who achieved remission was performed using two-sample t-test or the Wilcoxon rank-sum test for continuous variables and fisher tests for categorical variables. Results 66 patients were included in the analysis. Mean age was 49 years, majority female (76%), African (21%), African American (45%), GD (68%), TMNG (32%). 19 had TF (28.7%). There was no significant difference in characteristics between TF andremission groups prior to RAI. The RAI dose was not significantly different between the groups (21. 0;21.1mCi). However, patients given methimazole shortly after RAI were at significantly higher risk of TF compared to patients who did not receive methimazole after RAI (64% vs 89%, p=0. 04). Conclusion Previous studies report TF after RAI as high as 16%. Patients at our Hospital with TMNG or GD who underwent RAI had a higher TF rate of 28.7%. The high TF rate was not due to low RAI treatment dose. Randomized Controlled Trials have found 61%-86%(1) success with RAI dose ranging from 5.4 -15.7 mCi (1). In comparison, mean RAI dose at our hospital was high at 21. 0. Patients prescribed methimazole within 4 weeks of RAI were more likely to have TF at 6 months. Based on the results of this study, we will initiate a change in protocol at our institution to hold methimazole for at least 4 weeks after RAI to see if this lowers the TF rates.

ODP480 Failure to achieve remission post Radioactive iodine therapy

Abstract Background Radioactive iodine-131 (RAI) therapy is used to treat hyperthyroidism secondary to toxic multinodular goiter (TMNG) and Graves’ Disease (GD). The treatment failure (TF) rate for RAI as reported in previous studies is 8-16% (1). Most patients respond to RAI with normalization of thyroid function tests and improvement of clinical symptoms within 4–8 weeks. Previous studies also report higher TF rates amongst Black patients (2), but due to the low number of Blacks included in the study, identification of factors related to higher TF rates was difficult. Study Purpose Determine treatment failure rates in patients who underwent RAI treatment for hyperthyroidism and characteristics related to Treatment Failure. Methods This is a retrospective study that included patients treated with RAI for either TMNG or GD from 2014-2021 at an urban hospital. Patients with thyroid cancer, less than 18 years, or toxic adenoma were excluded. TF was defined as persistent hyperthyroidism 6 months after RAI. Remission was defined as euthyroid or hypothyroid state off of anti-thyroid hormones 6 months after RAI. Factors evaluated included age at RAI, gender, race, cause of hyperthyroidism, percentage uptake in pretreatment scan, peak Ft4 / Ft3 pre-treatment, RAI dose, and treatment with methimazole post RAI. Comparison of TF to those who achieved remission was performed using two-sample t-test or the Wilcoxon rank-sum test for continuous variables and fisher tests for categorical variables. Results 66 patients were included in the analysis. Mean age was 49 years, majority female (76%), African (21%), African American (45%), GD (68%), TMNG (32%). 19 had TF (28.7%). There was no significant difference in characteristics between TF and remission groups prior to RAI. The RAI dose was not significantly different between the groups (21. 0;21.1mCi). However, patients given methimazole shortly after RAI were at significantly higher risk of TF compared to patients who did not receive methimazole after RAI (64% vs 89%, p=0. 04). Conclusion Previous studies report TF after RAI as high as 16%. Patients at our Hospital with TMNG or GD who underwent RAI had a higher TF rate of 28.7%. The high TF rate was not due to low RAI treatment dose. Randomized Controlled Trials have found 61%-86% (1) success with RAI dose ranging from 5.4 -15.7 mCi (1). In comparison, mean RAI dose at our hospital was high at 21. 0. Patients prescribed methimazole within 4 weeks of RAI were more likely to have TF at 6 months. Based on the results of this study, we will initiate a change in protocol at our institution to hold methimazole for at least 4 weeks after RAI to see if this lowers the TF rates.

PSAT372 Percutaneous Polidocanol Injection as an Alternative Treatment Differentiated Thyroid Cancer Oligometastases

Abstract Introduction Differentiated thyroid cancer (DTC) presents central lymph node metastasis in 20-50% and lateral in 12-81% of patients and ipsilateral recurrence after lateral neck dissection occur in 8-26%. The treatment of choice is surgical reintervention with subsequent administration of radioiodine. Treatment with radioactive iodine together with surgical reintervention aimed at compartments dissection provides variable remission rates in some cases of only 30-50%. Surgical reintervention carries a greater risk of complications such as recurrent laryngeal nerve injury, secondary postoperative hypoparathyroidism and morbidity associated with fibrosis formation in the surgical bed. Due to the complications, minimal invasive techniques (MIT) have been described for the treatment of unresectable and/ or proliferative oligomestastases, such as percutaneous ethanol injection (PEI), radiofrequency ablation, microwave ablation and laser ablation. PEI is described for the ablation for thyroid cysts, thyroid and parathyroid adenomas and cervical lymph node metastases. It´s used in the treatment of lesions smaller than 10 mm2 and represents a berry picking type intervention. It requires multiple sessions and can cause pain due to extravasation, skin necrosis, laryngeal necrosis, and damage to the recurrent laryngeal nerve. PEI´s greatest limitation is the uneven and unpredictable ablation area. Guidelines don´t contemplate it as the first line of MIT, highlighting thermal ablation`s (TA) usefulness, however it´s mentioned to consider its selection according to resources availability. After stating the inconveniences with PEI and difficulties related to the TA availability, in our center we have used polidocanol as a safer and more effective alternative to ethanol. Percutaneous polidocanol injection (PPI) requires fewer sessions and lower dose, and its administration technique is like PEI. PPI is described only as an alternative treatment for PEI recurrent pure cysts. Objective Determine the efficacy of PPI for DTC oligometastasis treatment. Study Design: An experimental, prospective, comparative, and analytical study. Patients older than 18 years were selected, with oligometastasis due to DTC in whom ablation with polidocanol 3% was performed, considering therapeutic efficacy the disappearance of the treated node and reduction of thyroglobulin. Results 27 patients were studied, a total of 60 lymph nodes. 22 women and 5 men, age 47.0±14.2 years, all with papillary thyroid cancer and structural incomplete response, with a cumulative RAI dose of 50±176 mCi, Thyroglobulin without stimulation was 3.06±2.9 ng/dl. Number of sessions was 1 in 71.4%. Mean polidocanol 3% used was 1.9±1.28ml. Follow-up time was 7.8±4.9 months. Initial tumor volume 5.9±1.3 ml, tumor volume at follow-up 0.88± 0.21, (p=0.00), control thyroglobulin was 0.55±0.8.1 (p=0.10). Remission was modified in 52.4%, reduction in 42.9%, stability in 4.8% No patient documented progression. Conclusion Polidocanol is safe and effective so it should be considered for the treatment of oligometastasis in DTC, in selected cases when thermal ablation techniques are lacking. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.

Cure Rates After a Single Dose of Radioactive Iodine to Treat Hyperthyroidism: The Fixed-Dose Regimen.

IntroductionRadioactive iodine (RAI) has been used to treat hyperthyroidism for more than 70 years. Cure rates after RAI therapy range between 80% and 100%, with some patients requiring two or more doses. There is continued debate over which dosing regimen is optimal. We evaluated our cure rates after giving a single dose of radioactive iodine to treat hyperthyroidism using the fixed-dose regimen as opposed to the calculated-dose regimen.Materials and methodsWe retrospectively reviewed the clinical records of patients who had received their first single dose of RAI between 2016 and 2021. The patients had clinical and biochemical assessments every six weeks until six months post-RAI therapy, then every three months thereafter, if still not cured. Patients were deemed cured if they developed persistent hypothyroidism or euthyroidism after a single dose of RAI. The data included baseline demographics, adverse events, and cure rates after RAI treatment.ResultsOne hundred and thirty-eight patients received their first dose of RAI during the study period. Their mean ± standard deviation (SD) age was 56.9 ± 15.3 years, and there were 101 women and 37 men. The median duration of hyperthyroidism was 34 months, and 62% of the cases were affected by Graves’ disease. A majority of patients (90%) were on an antithyroid drug prior to RAI therapy. The median (interquartile range) dose of RAI received by the group was 559 (546-577) megabecquerels (MBq). Four patients (2.9%) reported adverse events shortly after receiving RAI. Our overall cure rate was 87.7% amongst patients who received a single dose of RAI therapy. This number consisted of 96 patients (69.6%) who developed hypothyroidism and 25 patients (18.1%) who remained euthyroid. Our one-year cure rate was 84.1%. Further analysis revealed that women had a greater cure rate than men over the study period (92% vs 75.7%, p = 0.017). ConclusionWe have evaluated cure rates after a single dose of RAI therapy for the treatment of hyperthyroidism at our center. Our results are comparable to those reported at other centers using a similar dosing regimen.

The effect of I-131 therapy on pregnancy outcomes after thyroidectomy in patients with differentiated thyroid carcinoma: a meta-analysis.

Studies on the effects of I-131 therapy on pregnancy outcomes after differentiated thyroid carcinoma (DTC) surgery showed inconsistent findings. The purpose of the study was to investigate the association between I-131 therapy and pregnancy outcomes in female DTC patients. PubMed, Embase, Cochrane Library, CNKI, and VIP were searched until November, 2020. Keywords included differentiated thyroid cancer, thyroid carcinoma, thyroid neoplasm, radioiodine, I-131, 131I, pregnancy outcomes, reproduction, fertility, abortion, preterm birth, and congenital malformation. Studies that provided the pregnancy outcomes in DTC patients who received I-131 therapy and those who did not receive I-131 therapy were included. Meta-analysis was performed in Stata/SE 12. A random or fixed effects model was adopted according to the result of heterogeneity test. Seven observational studies were eligible, involving 125,591 participants and 13,811 pregnancies. It showed that postoperative I-131 therapy for DTC had no significant effect on spontaneous abortion (OR = 1.05, P = 0.701), induced abortion (OR = 1.06, P = 0.859), abortion (OR = 1.07, P = 0.098), premature birth (OR = 1.02, P = 0.756), stillbirth (OR = 1.58, P = 0.364), and congenital malformation(OR = 1.00, P = 0.986). Cumulative RAI dose >3.7 GBq or <3.7 GBq had no significant effect on abortion (OR = 0.94, P = 0.252) and congenital malformation (OR = 1.05, P = 0.752).The group in which interval time between last I-131 therapy and pregnancy >1 year had significant lower risk of abortion than with interval <1 year (OR = 0.60, P = 0.000). Pregnancy is not recommended for DTC patients within 1 year after I-131 therapy.

Radioactive Iodine Treatment for Children and Young Adults with Thyroid Cancer in South Korea: A Population-based Study.

This study investigated radioactive iodine treatment (RAIT) patterns and the secondary cancer incidence among children and young adults receiving RAIT after thyroidectomy for thyroid cancer. This population-based cohort study used the Health Insurance Review and Assessment database of South Korea to identify a total of 18 617 children and young adults (0-29 years) who underwent thyroidectomy for thyroid cancer between 2008 and 2018. We recorded age at surgery, sex, the interval from surgery to RAIT, the doses of RAI, the number of RAIT sessions, and secondary cancer incidence. A total of 9548 (51.3%) children and young adults underwent 1 or more RAIT sessions. The initial dose of RAIT was 4.35 ± 2.19 GBq. The overall RAIT frequency fell from 60.9% to 38.5%, and the frequency of high-dose RAIT (>3.7 GBq) fell from 64.2% to 36.5% during the observational period. A total of 124 cases of secondary cancer developed during 120 474 person-years of follow-up; 43 (0.5%) in the surgery cohort and 81 (0.8%) in the RAIT cohort. Thus, the RAIT cohort was at an increased risk of secondary cancer (adjusted hazard ratio 1.52 [95% confidence interval 1.03-2.24], P = 0.035). The proportion of children and young adults receiving RAIT, and the RAI dose, fell significantly over the observational period. RAIT was associated with secondary cancers. This is of major concern in the context of child and young adult thyroid cancer survivors.

Value of Initial 18F-FDG PET/CT in Change of Management of Patients with Differentiated Thyroid Cancer as Compared to Post Ablative Whole Body Iodine Scan.

Differentiated thyroid cancers (DTC) are generally malignant endocrine tumors with good prognosis. 50-68% of patients with DTC's have local or regional recurrences depending on the patient's risk factors. The aim of the work: was to assess the rule of initial PET/CT in patients with DTC, evaluate the PET/CT as compared to post ablative WBS in DTC. The study included 124 patients with essentially pathologically proven differentiated cancer thyroid patients who had undergone or near total thyroidectomy and was eligible for RAI ablative dose. Pathological details, TG levels and post ablative I-131 WBS results were also reviewed and compared to PET/CT results. A short follow up period ranged from 4-6 months was used as a reference to validate the results of the current study. Results: we found the majority were females (74.2%), The mean age was 42 years old, papillary thyroid cancer was the dominant type in (83.1 %). (55.6%) was of low risk according to ATA Risk stratification and of stage I, Serum TG levels varied widely from 0.04-13564 with a median value of 8.28 ng/ml. 38 patients out of 124 (30.6%) showed positive FDG uptake in following sites thyroid operative bed, cervical and mediastinal LNs, pulmonary and bone metastases with the majority of pathological FDG uptake being at the loco-regional area in 38 patients. It was observed that PET/CT had positive results in older age groups especially those above 50 years old, patients with elevated serum TG levels with a median value of 40 ng/ml, Hurthle cell type and Intermediate /High risk groups. Therefore, patients with such criteria are more likely to benefit from initial PET/CT prior to their RAI dose. No significant correlation between the metabolic parameters and the avidity of RAI-131 positive findings was found. In 38 patients positive PET/CT results led to re-staging of 12 patients (9.6 %) and changed the management in 30 patients (24.2%). Conclusions: PET/CT changed the management in around 25 % of Differentiated thyroid cancers (DTC) that helped in validating the Theranostics concept which aimed at individualized patient management to achieve the best outcome.

A MATHEMATICAL MODEL FOR TREATMENT OF PAPILLARY THYROID CANCER USING THE ALLEE EFFECT

The incidence of thyroid cancer is rising all over the world, and the papillary subtype (PTC) is the primary factor for this increase. The presence of thyroid tumors is commonly associated with increased levels of cytokines, such as interleukin 6 (IL-6). Considering PTC patients treated with thyroidectomy and radioactive iodine [Formula: see text]I (RAI), we propose an ordinary differential system using four variables: the RAI activity, the number of cancer cells and the serum concentrations of IL-6 and thyroglobulin (Tg). Our objective is to study the efficacy of different therapeutic doses of RAI in the treatment of thyroid cancer. The Allee effect is taken into account when modeling cancer cells growth under the influence of IL-6. From the results obtained, the main factors and conditions correlated with successful treatment, such as the RAI activity used and the tumor response are addressed. The detection of minimal doses of RAI that can cause tumor extinction is performed, though this has also meant longer periods for tumor cell elimination. The critical number of tumor cells due to the Allee effect is analyzed and linked to the immune system or biological factors that can slow the progression of the tumor but are insufficient after thyroid resection surgery.

SUN-510 Prolonged RAIA Induced Thyroiditis After 131 I Therapy for Graves’ Hyperthyroidism

Radioactive iodine ablation (RAI) has been used for the treatment of Graves’ hyperthyroidism since 1946 and it is the primary recommended modality for Graves’ disease treatment in many countries. Acute painful radiation thyroiditis after radioiodine treatment for hyperthyroidism of Graves’ disease is considered uncommon. The prevalence is 1-5% in patients treated with 131I therapy for hyperthyroidism. Dose of RAI and thyroid volume can be precipitating factors for post radiation thyroiditis. The higher RAI dose increases the chance of RAI thyroiditis while the larger goiter size decreases the absorbed radiation dose in the thyroid gland. We present a 25-year-old Emirati male previously healthy, who was referred to our service for hyperthyroidism management. He presented with thyrotoxicosis in absence of goiter. All investigations revealed that graves’ disease is the primary cause of his hyperthyroidism. He was treated with RAI ablation 18.3 mCi. Day four after RAI, he presented with severe pain in the anterior neck associated with fatigue, tremor, palpitation and weight loss. Symptoms lasted for 6 weeks post RAI. There was laboratory evidence of thyrotoxicosis presented with further suppression of TSH and higher fT4 than the baseline. Acute radiation thyroiditis was diagnosed and has been commenced on propranolol 10mg BID. Symptoms completely resolved after 6 weeks of treatment and thyroid function returned to normal level. The patient has remained asymptomatic on continued follow up care till eventually became hypothyroid clinically and biochemically. Our case reflects that radioiodine thyroiditis can last for longer period and occur after larger doses of 131I treatment in absence of goiter. Our patient has RAIA induced thyroiditis lasted for 6 weeks post 18.3mCi of 131I, and has no goiter, which were both contributing factors for RAIA induced thyroiditis

MON-LB87 Recombinant Human TSH vs Thyroid Hormone Withdrawal Preparation for Radioiodine Ablation in Pediatric Differentiated Thyroid Cancer

Introduction: Recombinant human TSH (rhTSH) is commonly used to prepare patients with differentiated thyroid cancer (DTC) for radioiodine (I-131) ablation after total thyroidectomy (TT). In adults, rhTSH is associated with equivalent oncologic efficacy and improved health-related quality of life in comparison to thyroid hormone withdrawal (THW). In this study, we aimed to measure disease-free survival after rhTSH stimulation vs. THW in pediatric patients with DTC. Methods: A prospective database was analyzed for pediatric patients under the age of 21 with DTC who underwent TT and I-131 ablation with rhTSH preparation at a single tertiary institution from 2012 through 2018. These patients were compared against historical controls prepared with THW. Tumor stage, I-131 treatment details, disease-free survival, structural recurrence, biochemical recurrence (defined as serum Tg > 2 at one year), and postoperative serum TSH, thyroglobulin (Tg) and Tg antibody levels were recorded. The log-rank test was used to compare groups, and time to recurrence was estimated by Kaplan-Meier analysis. Results: Seventeen patients who received rhTSH (mean age, 16.6±3.2 [SD] years) were compared to 28 historical controls prepared with THW. No differences were observed in RAI dose (mean 2.3±0.7 mCi/kg), tumor stage, or follow-up time (median [IQR] 2.6 [1.1-3.1] years) between groups. The THW group exhibited a nonsignificantly greater recurrence rate (14 [50%], 7 with biochemical recurrence and 7 with structural recurrence) than the rhTSH group (three [18%], 2 with biochemical recurrence and 1 with structural recurrence, p=0.2). A trend toward improved disease-free survival was identified in those treated with rhTSH compared to THW. Conclusion: In this cohort of pediatric patients with DTC, we observed a trend toward improved disease-free survival among those prepared with rhTSH compared to historical controls prepared with THW. Long-term follow up is needed to better characterize outcomes associated with rhTSH stimulation prior to I-131 ablation in the pediatric population.

Outcomes Associated with Treatment of Hyperthyroidism with Radioiodine; A Single Center Retrospective Study

Background: Hypothyroidism and hyperthyroidism are prevalent conditions with potentially crippling health consequences that globally affect all populations. Hyperthyroidism is overproduction and persistent release of thyroid hormones that can be stratified into a number of subtypes with varying magnitudes and treatment outcomes. Despite of decades of treatment of hyperthyroidism with radioiodine, the success of treatment is still debatable and influenced by many factors. &#x0D; Objective: To determine outcomes associated with treatment of hyperthyroidism with radioiodine.&#x0D; Methods: All patients screened for thyroid disease at King Abdullah Medical City, Makkah in between 2012-17 were included in the analysis (N = 353). Eighteen questions were used to assess the presence or absence of symptoms associated with hyperthyroidism. 251 out of 353 patients were found eligible for screening with thyroid-stimulating hormone, free triiodothyronine (fT3) and free thyroxin (fT4). On the basis of laboratory analysis, 73 patients were eligible for the differing RAI therapeutic regimens. Treatment outcomes were assessed 6 months after the patients received RAI therapy, at which time they were classified as being hypothyroid, euthyroid, or hyperthyroid.&#x0D; Results: Females were predominantly affected by hyperthyroidism (75.2%) compared with males (24.8%). However, males were significantly more likely than females to have Graves’ ophthalmopathy (p &lt; 0.01), anxiety (p &lt; 0.05), and insomnia (p &lt; 0.05). A total RAI dose of ≤15 mCi was effective in eliminating most hyperthyroidism: ≤12 mCi, 26/29 = 89.7%; 12.1–15 mCi, 28/30 = 93.3%. Using bivariate analysis, the association of treatment effectiveness with each of the symptoms and comorbidities revealed significant correlations only for diabetes mellitus (rho = −0.428, p &lt; 0.001).&#x0D; Conclusions: Our data suggests that radioiodine remains an effective option of treating hyperthyroidism in most of the patients who qualify for it.

A Comparison between High Ablative Versus Usual Dosages of Iodine-131 in Inducing Hypothyroidism After One Year of Therapy in Hyperthyroid Patients

Background: Radioactive iodine-131 therapy is highly effective in treating patients with hyperthyroidism. An ablative dose is preferred by a number of endocrinologists, and, a fixed dose protocol seems to be better than a calculated dose in real practice.&#x0D; Objective: To check for hypothyroidism in hyperthyroid patients one year after RAI therapy, comparing between the results of high ablative versus usual dosages of RAI-131.&#x0D; Methods: This study included 174 hyperthyroid patients, 101 males and 73 females, divided into 2 groups, the first consisted of 162 patients given a usual fixed dose of RAI while the second consisted of 12 patients given a high fixed ablative dose of RAI. The study lasted about 2 years from August 2000 till July 2002 in the Specialized Centre for Endocrinology &amp; Diabetes, Baghdad.&#x0D; Results: Out of 162 patients in the first group, 11 patients (6.8%), developed hypothyroidism compared to 4 patients out of 12 (33.3% ) in the second group ( p &lt; 0.05).&#x0D; Conclusion: A high ablative dose RAI has a better outcome regarding hypothyroidism than a usual dose, although, endocrinologists have different opinions regarding this issue.&#x0D; &#x0D;