High-dose 131I Therapy Research Articles

Disrupted gut microecology after high-dose 131I therapy and radioprotective effects of arachidonic acid supplementation

BackgroundDespite the potential radiotoxicity in differentiated thyroid cancer (DTC) patients with high-dose 131I therapy, the alterations and regulatory mechanisms dependent on intestinal microecology remain poorly understood. We aimed to identify the characteristics of the gut microbiota and metabolites in DTC patients suffering from high-dose 131I therapy and explore the radioprotective mechanisms underlying arachidonic acid (ARA) treatment.MethodsA total of 102 patients with DTC were recruited, with fecal samples collected before and after 131I therapy for microbiome and untargeted and targeted metabolomic analyses. Mice were exposed to total body irradiation with ARA replenishment and antibiotic pretreatment and were subjected to metagenomic, metabolomic, and proteomic analyses.Results131I therapy significantly changed the structure of gut microbiota and metabolite composition in patients with DTC. Lachnospiraceae were the most dominant bacteria after 131I treatment, and metabolites with decreased levels and pathways related to ARA and linoleic acid were observed. In an irradiation mouse model, ARA supplementation not only improved quality of life and recovered hematopoietic and gastrointestinal systems but also ameliorated oxidative stress and inflammation and preserved enteric microecology composition. Additionally, antibiotic intervention eliminated the radioprotective effects of ARA. Proteomic analysis and ursolic acid pretreatment showed that ARA therapy greatly influenced intestinal lipid metabolism in mice subjected to irradiation by upregulating the expression of hydroxy-3-methylglutaryl-coenzyme A synthase 1.ConclusionThese findings highlight that ARA, as a key metabolite, substantially contributes to radioprotection. Our study provides novel insights into the pivotal role that the microbiota-metabolite axis plays in radionuclide protection and offers effective biological targets for treating radiation-induced adverse effects.

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

BackgroundI-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.MethodsFrom 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.ResultsThyroid 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.ConclusionI-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.

Clinical Outcomes of Radioactive Iodine Redifferentiation Therapy in Previously Iodine Refractory Differentiated Thyroid Cancers.

Objective: Redifferentiation therapy (RDT) can restore radioactive iodine (RAI) uptake in differentiated thyroid cancer (DTC) cells to enable salvage 131I therapy for previously RAI refractory (RAIR) disease. This study evaluated the clinical outcomes of patients who underwent RDT and identified clinicopathologic characteristics predictive of RAI restoration following RDT. Methods: This is a retrospective case series of 33 patients with response evaluation criteria in solid tumors (RECIST)-progressive metastatic RAIR-DTC who underwent RDT between 2017 and 2022 at the Mayo Clinic (Rochester, MN). All patients underwent genomic profiling and received MEK, RET or ALK inhibitors alone, or combination BRAF-MEK inhibitors for 4 weeks. At week 3, those with increased RAI avidity in metastatic foci received high-dose 131I therapy. Baseline and clinicopathologic outcomes were comprehensively reviewed. Results: Of the 33 patients, 57.6% had restored RAI uptake following RDT (Redifferentiated subgroup). 42.1% (8/19) with papillary thyroid cancers (PTC), 100% (4/4) with invasive encapsulated follicular variant PTCs (IEFV-PTCs), and 100% (7/7) with follicular thyroid cancers (FTC) redifferentiated. All (11/11) RAS mutant tumors redifferentiated compared with 38.9% (7/18) with BRAF mutant disease (6 PTC and 1 IEFV-PTC). 76.5% (13/17) of redifferentiated and 66.7% (8/12) of non-redifferentiated patients achieved a best overall RECIST response of stable disease (SD) or non-complete response/non-progressive disease. Both subgroups had a median 12% tumor shrinkage at 3 weeks on drug(s) alone. The redifferentiated subgroup, following high-dose 131I therapy, achieved an additional median 20% tumor reduction at 6 months after RDT. There were no statistically significant differences between both groups in progression free survival (PFS), time to initiation of systemic therapy, and time to any additional therapy. Of the entire cohort, 6.1% (2/33) experienced histologic transformation to anaplastic thyroid cancer, 15.1% (5/33) died, and all had redifferentiated following RDT and received 131I therapy. Conclusion: RDT has the potential to restore RAI avidity and induce RECIST responses following 131I therapy in select patients with RAIR-DTC, particularly those with RAS-driven "follicular" phenotypes. In patients with PTC, none of the evaluated clinical outcomes differed statistically between the redifferentiated and non-redifferentiated subgroups. Further studies are needed to better characterize the long-term survival and/or safety outcomes of high-dose RAI following RDT, particularly whether it could be associated with histologic anaplastic transformation.

SAT520 Efficacy of Radioactive Iodine Redifferentiation Therapy in Previously Iodine Refractory Differentiated Thyroid Cancers

Abstract Disclosure: D. Toro-Tobon: None. J.C. Morris: None. C. Hilger: None. C.S. Peskey: None. D.M. Jolanta: None. M.M. Ryder: None. Objective: Patients with metastatic differentiated thyroid cancer (DTC) that are radioactive iodine (RAI) refractory (RAIR) have a poor prognosis. Redifferentiation therapy (RDT) has emerged as a potential approach to restore RAI avidity in this disease. The aim of this study was to examine the efficacy and predictors of RAI restoration in RAIR disease, as well as examine the outcomes of patients re-treated with high dose RAI following RDT. Methods: A retrospective review was conducted of 33 patients with RECIST-progressive metastatic RAIR-DTC who underwent RDT between 2017 and 2022 at the Mayo Clinic. All patients underwent genomic profiling, and either MEK inhibitor alone or combination BRAF-MEK inhibitors were prescribed for 4 weeks. At week 3, Thyrogen-stimulated I-123 whole body scans were performed. Those with increased RAI avidity in metastatic foci received high dose I-131 therapy using a previously published modified dosimetry protocol. Baseline and clinicopathologic outcomes were comprehensively reviewed. Results: Of the 33 patients, 12 of 23 (52%) with papillary thyroid cancers (PTC), 4 of 4 (100%) with follicular variant PTCs (FV-PTC), and 7 of 7 (100%) with follicular thyroid cancers (FTC) had restored RAI avidity following RDT using dabrafenib/trametinib (7 for BRAF mutant disease) or trametinib monotherapy (12 for RAS mutant disease). All 11 (100%) RAS mutant tumors (2 PTC, 3 FV-PTC, and 6 FTC) had RAI avidity restoration compared to 7 (36%) with BRAF mutant disease (6 PTC, and 1 FV-PTC). Of the 19 patients (57%) with restored RAI avidity (responders), 18 (94%) received I-131 with a median dose of 294 mCi. The median thyroglobulin (Tg) in responders was 294 mIU/L as compared to 29 mIU/L in non-responders. Following RDT-facilitated I-131 treatment, 94.7% achieved RECIST defined objective response (complete or partial response, stable disease, non-complete response/non-progressive disease) with a median progression free survival of 18 months and an overall survival of 30 months. Overall, patients with FTC (p=0.01), RAS mutation (p&amp;lt;0.001), Tg of 294 mIU/L or more (p=0.03), largest tumor diameter of 1.7 cm or less (p=0.05), bone metastasis (p=0.007), and without locoregional nodal disease (p=0.04), were more likely to demonstrate restored RAI avidity following RDT. Of the entire cohort, 2 (6%) patients experienced histologic transformation to anaplastic thyroid cancer and 5 (15%) patients died, all had had RAI restoration and received high-dose RAI following RDT. Conclusion: RDT has the potential to restore RAI avidity and induce RECIST responses following I-131 therapy in select patients with RAIR-DTC, particularly those with RAS mutations and ‘follicular’ phenotypes. Further studies are needed to better characterize the long-term survival and/or safety outcomes of high-dose RAI following RDT, particularly whether it could be associated with histologic transformation. Presentation Date: Saturday, June 17, 2023

Influence of COVID 19 Pandemic on Shifting High Dose I-131 Therapy to Home Isolation Practice.

COVID-19 pandemic forced medical facilities to postpone many elective services, including hospitalization for radioactive iodine (I131) therapy. This has negative impact on patients in need of this therapy in many countries, including Kingdom of Saudi Arabia (KSA), as they mandate hospital admission in special isolation room for few days to receive high dose I31 therapy. In other countries, this therapy is not significantly affected as high dose I-131 therapy on outpatient basis with home isolation (HDITO) is a well-established safe and effective therapeutic policy. Aim: To assess opinion of health care providers concerned with I131 therapy in KSA about HDITO and to verify acceptance to apply HDITO during current pandemic. Material and Methods: questionnaire about HDITO was electronically dispensed to health care providers in KSA and results were collected within four weeks to be statistically analysed. Results: Out of 101 respondents, about two thirds confirmed significant delay in giving high dose I-131 therapy due to COVID19. Half respondents agreed to apply HDITO, 85% agreement was reported for those frequently involved in I-131 therapy. Avoiding treatment delay with its unfavourable consequences represents the foremost etiological factor for agreement to apply the policy of giving HDITO, followed by avoiding overwhelming of health care system and saving patients from catching viral infection during the current pandemic . Respondent's agreement for application of the policy of HDITO was conditioned with presence of separate bedroom and bathroom for the patient, strict application of radiation safety instructions and proper waste disposalRespondents favour the use of a communication method with the patient and his/her family as hot line for answering any question about radiation protection issues raised at any time during post therapy period. Around 63% of respondents agreed about conducting a national multi-centric clinical study, providing approval from all related governmental radiation safety authorities in KSA, to ensure the safety and efficacy of HDITO. 50% Are so willing to participate in this study, this figure increases to 85% for those who are more frequently involved in I-131 therapy. CONCLUSION: Many healthcare professionals in KSA agreed to apply the policy of HDITO that appears to be good alternative to routine hospital admission during COVID19 pandemic. This study encourages performing a multi-centric research in KSA about HDITO, on approval from higher radiation safety authorities, to confirm its safety and efficacy to be applied in the future during any other pandemic.

Clinical Outcome of Parotid Gland Massage for Preventing Parotid Gland Dysfunction in Patients Treated with Radioiodine Therapy for Differentiated Thyroid Cancer: a Prospective Longitudinal Follow-Up Study

Background and Objectives: The aim of this study was to determine the clinical effectiveness of parotid gland (PG) massage for the prevention of PG dysfunction after administration of radioiodine (I-131) therapy for treatment of differentiated thyroid cancer (DTC). Materials and Methods: One hundred patients with DTC with planned high-dose I-131 therapy were enrolled in the clinical trial and randomized into two groups (massage and non-massage group). Serum amylase values were obtained before and 24 h after I-131 therapy, and salivary gland scintigraphy (SGS) were taken before and at eight months after the I-131 therapy. Additional SGS (addSGS) were taken when the patients complained symptoms related to salivary gland dysfunction. Questionnaire surveys were performed before and until two years after I-131 therapy. Results: Ninety-five of 100 patients finished the study protocol. Changes in survey scores tended to be higher in the non-massage group. The non-massage group had more severe symptoms related to salivary gland dysfunction. Among 32 patients who underwent addSGS, 27 had normal 8-month SGS. Of these 27 patients, 18 (66.7%) had salivary gland dysfunction on the addSGS. Amylase values were significantly increased in patients with normal 8-month SGS but abnormal addSGS, as compared to patients who were normal on both 8-month SGS and addSGS (p=0.046). Amylase difference values were a significant predictor of abnormal addSGS (p=0.002). Conclusion: PG massage reduced symptoms related to salivary gland dysfunction. The PG massage may be helpful in preventing damage to salivary glands caused by I-131 therapy.

The Preventive Effect of Parotid Gland Massage on Salivary Gland Dysfunction During High-Dose Radioactive Iodine Therapy for Differentiated Thyroid Cancer: A Randomized Clinical Trial.

To evaluate the preventive effect of parotid gland (PG) massage for PG damage during the I therapy, we prospectively investigated the serum amylase value and salivary gland scintigraphy (SGS) after I therapy. One hundred patients with thyroidectomized differentiated thyroid cancer who underwent high-dose I therapy were enrolled in the clinical trial and randomized into 2 groups (PG massage group and nonmassage group). The serum amylase value was obtained before and 24 hours after I therapy, and the SGSs were also taken just before and at 8 months after the I therapy. Change in serum amylase value and SGS was compared between PG massage and nonmassage groups. The difference value of serum amylase was significantly lower in PG massage group than in nonmassage group (P = 0.0052). Worsening of PG function on SGS was observed in 43 (45.3%) of the 95 patients. The incidence rate of PG abnormality on F/U SGS was significantly lower in PG massage group than in nonmassage group (odds ratio, 0.3704; P = 0.0195). In the multiple regression analysis, PG massage significantly affected the abnormality on the 8-month F/U SGS (rpartial = -0.2741, P = 0.0090) after adjusting for clinical variables (age, sex, TNM stage, TSH preparation methods for the I therapy, and I dose). PG gland massage significantly reduced the incidence rates of salivary gland dysfunction on the 8-month F/U SGS and the level of the serological marker of salivary gland destruction after I therapy. Therefore, PG gland massage could alleviate salivary gland damage related to I therapy.

Comparison of I-131 Biokinetics after Recombinant Human TSH Stimulation and Thyroid Hormone Withdrawal Measured by External Detector in Patients with Differentiated Thyroid Cancer.

The aim of this study was to compare radioactive iodine (I-131) biokinetics after recombinant human TSH stimulation (rhTSH) and thyroid hormone withdrawal (THW) in patients with differentiated thyroid cancer (DTC). External effective dose rates were measured using external detectors and imaged quantitatively at the time of discharge from the isolation wards. We retrospectively analyzed 32 patients who had been diagnosed with DTC, papillary or follicular, and underwent remnant ablation after either rhTSH stimulation (n=22) or THW (n=10). The uptake of I-131 by remnant thyroid tissue was measured from 20.0 cm, 100.0 cm and 200.0 cm distances using a handheld external detector. The remnant thyroid tissue measured by the whole body images two to five days from administration was 10.7+26.0% (range 0.5 to 60.0%). The values measured at 20 cm were best correlated to the thyroid residual uptake measured by SPECT/CT. The half-lives of I-131washout (T1/2) in rhTSH group measured by external detector were shorter than those of THW group. T1/2 becomes longer when it was measured over longer distances. They were 10.9, 12.3 and 13.1 hours at distances of 20, 100, and 200 cm in rhTSH group, respectively. The TWH group showed 12.8, 14.9 and 17.7 hours, respectively. We conclude that I-131 biokinetics can be measured by external detector after high dose I-131 therapy for DTC. It showed that washout of I-131 was faster after rhTSH stimulation than THW, and slower in patients with distant metastasis than those without metastasis.

The minimum amount of fluids needed to achieve the fastest time to reach permissible level for release in well-differentiated thyroid patients undergoing high-dose I-131 therapy.

Radioiodine (131I) therapy is the mainstay of treatment for patients who had undergone total thyroidectomy for well differentiated thyroid carcinoma. Increased fluid intake has always been encouraged to minimize the risk of non-target organ exposure to I-131radiation. This study aimed to determine the minimum amount of fluids needed for patients to have the fastest time to achieve permissible level for release after high dose I-131therapy. Methodology: All the patients who were treated with high dose I-131from 18th January 2016 till 31st December 2016 in Hospital Pulau Pinang, Malaysia were recruited. The data from 126 patients on thyroxine hormone withdrawal (THW) group and 18 patients on recombinant human thyroid stimulating hormone (rhTSH) group were analysed. There is no change in patient management in terms of preparation, dose or post therapy whole-body scan. Fluid intake of patients were monitored strictly and whole-body retention of I-131are measured using ionizing chamber meter immediately after ingestion of I-131then at 1 hour, 24 hours, 48 hours, 72 hours and 96 hours. Results: The median time to achieve permissible release limit (50 μSV/hr at 1 meter) was 21.6 hours and 22.1 hours post-ingestion of I-131in the THW and rhTSH group respectively. The minimum amount of fluid needed to reach permissible release limit in the fastest time was 2,103 ml and 2,148ml for the THW and TSH respectively. Conclusion: Clinicians would be able to evidently advise their patient on the amount of fluid to consume and utilize their isolation wards faster to treat more patients.

Unusual Sites of Metastatic and Benign I 131 Uptake in Patients with Differentiated Thyroid Carcinoma.

Introduction:Differentiated thyroid carcinoma (DTC) is the most common pathological type of thyroid carcinoma, which includes papillary and follicular subtypes. DTC is usually indolent, characterized by good prognosis, and long-term survival. Total thyroidectomy is the mainstay of treatment in DTC which is followed by diagnostic whole body 131I (WBI) scan. Like other primary malignancies of the head and neck, DTC follows a consistent pattern of spread in the cervical LNs. The central compartment, level VI and VII, is the first sentinel node followed by spread to the lateral compartments levels II–V, followed by the contralateral side. Inspite of nodal involvement, DTC usually have a favourable outcome. Presence of extrapulmonary distant metastases could predict a poor prognosis for high-dose 131I therapy. However, distant metastasis occurs often as a grave event and mortality rates vary depending on metastatic sites.Aim and Objectives:A range of rare 131I concentrating DTC deposits in sella, orbit, choroid, skeletal muscles, liver, skin, costochondral soft tissue, pancreas and kidney, and a few benign 131I concentrating sites are being depicted.Materials and Methods:Metastatic sites from DTC can be easily identified by performing a whole body 131I (WBI) scan along with a stimulated thyroglobulin (Tg) estimation (TSH >30 uIU/ml). Apart from thyroid and thyroid-related diseases, certain benign non-thyroidal pathologies can concentrate radioiodine (131I). From 13,000 of our patients who underwent radioiodine scan for thyroid cancer, we have selected a few cases of 131I concentrating benign and malignant lesions for illustration.Results:Out of 13000 DTC patients who underwent whole body 131I scintigraphy in our department from Jan 2007 till Mar 2018, 25 patients revealed benign sites of 131I uptake. 61 % patients had residual thyroid tissue with or without associated nodal involvement. Remaining patients had distant metastases. Rare sites of functioning thyroid metastases and benign sites of I 131 uptake have been selected for illustration.Conclusion:Apart from the WBI (two-dimensional, planar) images, single-photon emission computed tomography-computed tomography (SPECT-CT) has been incremental in localizing benign lesions which greatly depends on their location. This pictorial review highlights the need to create an awareness to detect metastatic deposits of DTC at unexpected sites. Otherwise patients will need further investigation to rule out unsuspected sites of functioning distant metastases.

A Study on the Effective Half-life after the High Dose Radioactive Iodine (131I) Therapy for Thyroid Cancer Patients

High-dose 131I therapy has been generally carried out to remove remaining thyroid tissue or to cure metastasize lesion of patients who received full thyroidectomy due to differentiated thyroid cancers. In case high-dose 131I therapy is carried out for a patient, the patient should be hospitalized being isolated for a certain period in order to restrict the amount of exposure to radiation of people at large from the patient within the limit of a level of radiation. Effective half-life is an important value to calculate how family members are exposed to radiation from a patient or to decide the period of isolation of the patient from the family members. Therefore, in this study we calculated the effective decay constant, effective half-life and period of isolation of high-dose 131I therapy patient using NM670 SPECT/CT. As a result of carrying out this study, the effective half-life of high-dose 131I therapy patients was derived and the time to reach the discharge level of 1.2 GBq was confirmed. When they were compared with each other in each of curative doses, the effective half-life did not have significant difference, but the time when the level of radiation remaining in the interior of the body to reach the criteria of isolation and discharge showed significant difference and it could be confirmed that the higher the curative dose the longer the period of isolation becomes. When the effective half-lives in each type of preparation were compared with each other, they did not show significant difference. However, When the times to reach the level of radiation that is the criteria of isolation and discharge in each type of preparations, they showed significant difference. The cause of the shortening of the isolation period for rhTSH patients group is decided to be low curative dose. Accordingly, if the current national health insurance (the insurance is applied to using of rhTSH in 3.7 GBq or lower) is maintained, while discerning them in each of types of preparation, we would be able to discharge patients at the time earlier than the current period of isolation (2 nights and 3 days).

Outcome of radioiodine therapy in patients with papillary thyroid carcinoma concurrent with Hashimoto′s thyroiditis

Objective To evaluate the impact of low-dose 131I therapy and high-dose 131I therapy on the clinical outcome in PTC patients coexisting with Hashimoto′s thyroiditis (HT). Methods A total of 140 non-distant metastatic PTC patients (16 males, 124 females, age range: 16-66 years) from July 2010 to December 2014 were enrolled in this retrospective study. Patients concurrent with HT (n=84, group A) were divided into low-dose group (1 110 MBq, n=56, group A1) and high-dose group (5 550 MBq, n=28, group A2) according to 131I ablation dose. Patients without HT (n=56) were enrolled as control group (group B), and received 1 110 MBq of 131I. The thyroid remnant ablation outcome was evaluated according to 131I diagnostic whole-body scan (Dx-WBS), neck ultrasonography (US), serum Tg and TgAb level 6-8 months after 131I ablation therapy. The successful ablation rates were compared by χ2 test. Kruskal-Wallis rank sum test was also used. Results There were no significant differences among the 3 groups in terms of both clinicopathological features and postoperative remnant thyroid (H: 0.203-2.944, χ2: 0.271-0.970, all P>0.05). When negative Dx-WBS and US were deemed as successful ablation criterion, complete ablation rate was found significantly more in group B (94.6%, 53/56) than that in group A1 (82.1%, 46/56; χ2=4.264, P 0.05). When combining negative sTg (sTg 0.05), and no difference was observed between group A2 (12/15) and group A1 (χ2=1.320, P>0.05). Conclusion Non-distant metastatic PTC patients coexisting with HT has undesirable 131I ablation outcome compared with those without HT, increasing 131I dose is unhelpful to enhance efficiency of remnant ablation for PTC patients with HT. Key words: Thyroid neoplasms; Hashimoto disease; Radiotherapy; Iodine radioisotopes; Treatment outcome

Low-dose and high-dose 131I therapy for low and intermediate risk differentiated thyroid cancer: a randomized controlled clinical study

Objective To compare the ablation efficacy and therapy response with low-dose (1.1 GBq) and high-dose (3.7 GBq) 131I in postoperative patients with low and intermediate risk DTC. Methods A total of 140 patients (37 males, 103 females, age range: 18-75 years) were enrolled from October 2014 to June 2015, and randomly assigned to low-dose group (1.1 GBq 131I) and high-dose group (3.7 GBq 131I). Diagnostic whole body scan was performed (6±3) months after radioiodine(131I, 185 MBq) therapy after L-T4 withdrawal. TSH, FT3, FT4, Tg, TgAb and neck ultrasonography were also examined. χ2 test and Fisher′s exact test were used to analyze the data. Results The data of 132 patients (33 males, 99 females, age range: 18-75 years) could be evaluated, and the half of them received low-dose radioiodine and the other half received high-dose radioiodine. Thyroid ablation was complete in 55 patients (55.6%, 55/99). The successful ablation rates in low-dose group and high-dose group were 52.7%(29/55) and 59.1%(26/44) respectively, with no significant difference (χ2=0.74, P=0.548). In the low-dose group, 80.3%(53/66) had excellent response, 19.7%(13/66) had indeterminate response, and no patients had biochemical incomplete response. In the high-dose group, the proportions were 84.8%(56/66), 10.6%(7/66) and 4.5%(3/66), respectively. There were no significant differences between the two groups (χ2=4.88, P=0.087). Conclusion The ablation efficacy and therapy response between low-dose group and high-dose group have no significant differences in postoperative patients with low and intermediate risk DTC. Key words: Thyroid neoplasms; Radiotherapy; Iodine radioisotopes; Treatment outcome

Radiation exposure levels in close proximity to therapeutic patients treated for thyroid carcinoma with high dose I-131

High dose I-131 therapy is administered to thyroid cancer patients after thyroidectomy. In the treatment process when a radiopharmaceutical is administered to patients, they become a mobile source of radiation. After the treatment, contamination may arise from large amount of activity, which is excreted during the period of hospitalization. To reduce the rate of exposure it is essential to monitor workplace. This study determines the rate of radiation exposure in the room where the patient stays during the period of hospitalization as well as the adjacent rooms and surrounding areas. DOI: http://dx.doi.org/10.3329/bjnm.v17i1.22491 Bangladesh J. Nuclear Med. 17(1): 50-54, January 2014

Investigation of the level of safety for out-patients treated with high dose of 131I in Sudan

The aim of this study was to describe and analyze the patterns of radiation exposure of contacts of Sudanese patients treated with radioactive 131I on an out-patient basis and post discharge after high dose 131I therapy, and also to compare the family members׳ results with dose constraints proposed by the European Commission (EC). Thermoluminiscent dosimeters (Model TLD-100H) were used to estimate the effective doses for 40 family members of fifteen patients treated with 131I. The family members wore a TLD in front of the chest for 10 days. The effective dose ranged from 0.23 to 6.74mSv (mean 1.75mSv). These findings may be considered when establishing new national guidelines concerning radiation protection and release of patients after a treatment with radioiodine therapy.

Both F-18 FDG-avidity and Malignant Shape of Cervical Lymph Nodes on PET/CT after Total Thyroidectomy Predict Resistance to High-dose I-131 Therapy in Patients with Papillary Thyroid Cancer.

Objective:Resistance of metastatic lymph nodes (LNs) to high dose I-131 therapy is associated with high morbidity in patients with differentiated thyroid cancer. We evaluated the role of F-18 FDG PET/CT in the prediction of resistance to high dose I-131 therapy in patients with papillary thyroid cancer.Methods:The subjects were 307 patients who underwent total or near total thyroidectomy followed by high dose (5.55-6.66 GBq) I-131 therapy. We divided the patients into three subgroups by visual assessment of regional LNs: FDG-avid LNs with a malignant shape on CT (PET/CT-positive group), FDG-avid LNs with a benign shape on CT (PET/CT-intermediate group) and no FDG-avid lesion (PET/CT-negative group). We measured the maximum SUV (SUVmax) of FDG-avid LNs in each patient. The presence or absence of focal increased uptake of I-131 was evaluated by whole body scan (WBS), and was denoted as WBS-positive group or WBS-negative group, respectively. Resistance to therapy was defined as presence of thyroglobulin (Tg) in serum (Tg ≥1.0 ng/ml) 3-6 months after I-131 therapy. Univariate and multivariate analyses were performed to determine the relationship between resistance to I-131 therapy and various clinico-pathologic variables.Results:PET/CT-positive, intermediate, and negative groups included 20 (6.5%), 44 (14.3%) and 243 (79.2%) patients, respectively. The mean SUVmax was significantly higher in the PET/CT-positive group than that of the PET/CT-intermediate group (4.6 vs. 2.7, P <0.001). Univariate analysis revealed that the PET/CT-positive group (P <0.001), T2-4 stage (P <0.001), N1b stage (P = 0.001), lower dose (5.55 GBq) of I-131 (P <0.001), and the WBS-positive group (P = 0.029) were associated with resistance to therapy. In multivariate analysis, the PET/CT-positive group, lower dose of I-131, N1b stage, and T2-4 stage remained significant with odds ratios of 10.07 (P <0.001), 3.82 (P <0.001), 3.58 (P = 0.001), and 2.53 (P = 0.009), respectively.Conclusion:FDG-avidity and malignant shape of cervical LNs on pre-therapy FDG PET/CT were a strong risk factors predicting resistance to high dose I-131 therapy. A lower dose of administered I-131 (5.55 GBq) and more extensive tumors (T2-4 and N1b) were also associated with resistance to high dose I-131 therapy.

Improved Detection of Lung or Bone Metastases with an I-131 Whole Body Scan on the 7th Day After High-Dose I-131 Therapy in Patients with Thyroid Cancer

The purpose of this study is to compare post-therapy third day and seventh day I-131 whole body scans (3DWBS and 7DWBS) in detecting lung or bone metastasis from well-differentiated thyroid cancer. We enrolled 52 patients with lung or bone metastasis out of 1,152 patients who were treated with high-dose I-131 therapy from January 2008 to June 2009. All patients underwent 3DWBS and 7DWBS. I-131 avidity was classified into three grades: no uptake, suspicious for uptake, and definite uptake. We compared the presence and grades of metastatic lesions on each scan. We categorized all cases into three groups based on I-131 uptake on each scan and compared several clinical parameters including FDG uptake and thyroglobulin (Tg) level among the groups. Sixty metastatic cases from 52 patients (45 lung and 15 bone metastases) were included. In 35 cases, I-131-avid metastatic lesions were detected by both 3DWBS and 7DWBS (group A). In 15 cases, metastatic lesions were missed on 3DWBS but detected on 7DWBS (group B). In 10 cases, I-131 uptake was not detected on either 3DWBS or 7DWBS (group C). Ten of 45 cases (22.2%) of lung metastasis that were negative on 3DWBS were detected on 7DWBS (p = 0.002). Five of 15 cases (33.3%) of bone metastasis that were negative on 3DWBS were detected on 7DWBS (p = 0.0625). The serum Tg level (TSH stimulated) was significantly different among groups A, B, and C (p = 0.0030). However, after exclusion of cases without a history of I-131 therapy, there was no significant difference in serum Tg level among the groups (p = 0.2330). The number of cases with a prior history of metastasis was higher in group A than in group B (p = 0.0069). However, there was no significant difference in prior history of metastasis between groups A and C (p = 0.8107). 7DWBS showed more lung or bone metastatic lesions than 3DWBS. After high-dose I-131 therapy, 7DWBS should be considered regardless of the results of the 3DWBS for the diagnosis of lung or bone metastasis from well-differentiated thyroid cancer.

The Effect of High-Dose Radioiodine Treatment on Lacrimal Gland Function in Patients With Differentiated Thyroid Carcinoma

There are a limited number of case reports confirming the radioiodine (I-131) presence in tears and only a few case reports of lacrimal gland dysfunction after I-131 therapy. This study was designed to clarify whether lacrimal gland function can be affected by I-131 therapy. We studied 100 eyes of 50 patients who had received high doses of I-131 for treatment of differentiated thyroid carcinoma and 100 eyes of 50 age- and sex-matched control individuals without a history of interfering conditions. The exposed group was studied at least 3 months after their last I-131 therapy. Dry eye symptoms and Schirmer test values (wetting level in millimeters per 5 minutes) of an exposed group were compared with those of an unexposed group. Fifty-one percent of the exposed eyes and 50% of the unexposed ones revealed at least 1 of the dry eye symptoms. There was no significant difference in symptoms between 2 groups, except for burning sensation and eye redness, which were significantly higher in the exposed eyes. A lower Schirmer test value was noted in the exposed group, 14.5 +/- 10.8 mm, when compared with that in controls, 18.2 +/- 11.0 mm (P = 0.016), and the relative risk of an abnormal Schirmer test in exposed cases to control group was 1.78 +/- 0.62. Correlation coefficient analysis showed no significant relationship between Schirmer test values and cumulative doses of administered I-131. Reduction in the tear secretion from lacrimal glands is seen after high-dose I-131 therapy; however, their symptoms are no greater than an unexposed population.

Elevated thyroglobulin levels and negative I-131 whole body scans: Six-year experience in United Arab Emirate

16508 Purpose: This is a retrospective study of thyroid cancer patients seen at Oncology Department at Mafraq Hospital/UAE from 1/1999 to 12/2005. Clinical data, prognostic factors and treatment outcomes were studied, special emphasis was put on patients with elevated Serum Thyroglobulin (TG) and negative I-131 whole body scans. Patients and Methods: Total of 144 patients were fully evaluated, intent to treat analysis was used. All patients were treated surgically and post-op thyroid technician 99 scan were performed. I-131 ablation was given if the tumor size was =1 cm or if =1 cm (micropapillary) and multi-focal. Post ablation scan was done on day 10 and thyroxin was given in suppressive doses. Periodic evaluations were done with TG level, I-131 whole body scan, neck US and CXR. Plain CT scans and PET scans were done in selected cases. Results: Male to female ratio 1:2.42, non-smokers were 90%, non-alcoholics were 99%, Diabetes and Hypertension were associated in 28% of cases, family history of thyroid cancer was noted in 8%, papillary carcinoma was seen in 85.8%, follicular cancer in 11.6%, hurthel cell cancer in 0.83% and medullary cancer in 0.17%. Vascular and lymphatic invasion was noted in 29% of all cases. Interesting all patients with vascular or lymphatic invasion relapsed locally or distantly. Post-operative thyroid scan showed residual thyroid tissue in 96% of cases. During follow up TG levels (cut off 5.0 ng/ml) were elevated in 52 patients (37% cohort). Diagnostic I-131 scans were done in 36 patients and were positive in 24 patients (67%) and negative in 12 patients (33%). In the 12 patient group of research interest with elevated TG and negative I-131 whole body scans, 9 received high dose I-131 therapy. Of these patients 8 (88%) showed positive post therapy scan and 1 (12%) showed negative post therapy scan. Conclusion: 1. TG is more sensitive marker than diagnostic I-131 scan in making treatment decisions. 2. Lympho vascular invasion has adverse prognostic value. No significant financial relationships to disclose.

Radiation Safety Protocol for High Dose 131I Therapy of Thyroid Carcinoma in Patients on Hemodialysis for Chronic Renal Failure

Iodine ablation therapy for thyroid cancer on patients receiving dialysis poses unique radiation safety challenges. Exposure to gamma and beta negative particles by the hemodialysis (HD) staff is a concern that has not been well studied. A 53-y-old male patient on HD for chronic renal failure was scheduled for 131I high dose therapy as treatment for thyroid papillary carcinoma. The patient was on HD every other day, prior to ablation. A high dose of 131I (3,607.5 MBq) was required. The patient was admitted for 131I therapy, and continued HD. Thyroid cancer ablation therapy was administered according to our institutional protocol. New radiation safety measures were developed and implemented in order to give the patient an optimal treatment dose, reduce radiation to the patient (critical organs and whole body), and to protect the HD personnel. This included placing two lead shields between the patient and the HD nurse, and HD monitoring by two alternating nurses to reduce their radiation exposure. Film badges were used to measure radiation exposure to the nursing staff. Dosimetry calculations were obtained to determine radiation absorbed doses by the optic lens, skin, and whole body. Quality control verification for this shielding arrangement proved to be effective in protecting the HD staff against gamma and beta negative radiation from recent 131I high dose therapy. Implementation of this model proved to be an effective and adequate radiation safety protocol for limiting radiation exposure to the HD staff. The patient was given 3607.5 MBq for optimal treatment after HD. Hemodialysis was repeated after approximately 48 and 96 h to remove excess 131I and reduce radiation to the patient.