Remnant Ablation Research Articles

Association between clinical and tumor features with postoperative thyroglobulin in pediatric papillary thyroid cancer

BackgroundWhy certain patients after total thyroidectomy for thyroid cancer who do not have distant metastasis have increased serum stimulated thyroglobulin (s-Tg) is unknown. The aim of our study was to systematically investigate the associations of preablation s-Tg with clinical and tumor characteristics in children and young adults less than 20 years old after total thyroidectomy for papillary thyroid cancer. MethodsWe performed a retrospective analysis of 93 children and young adults younger than 20 years old who had undergone total thyroidectomy and were without known distant metastases who underwent remnant ablation. Before any remnant preablation, we assessed the association of s-Tg after thyroid hormone withdrawal with the clinical and histopathologic characteristics according to the American Thyroid Association pediatric initial risk classification system. ResultsThe median age was 18 years, and the majority of patients were female (80%). The preablation s-Tg ranged from 0.02 to 902.00 ng/mL, with a median of 9.2 ng/mL. Forty-five (48%) patients had an increased preablation s-Tg >10 ng/mL. In multivariate analyses of clinical and tumor characteristics, high-risk stratification and high neck uptake (>2%) were the independent predictive factors for the presence of an increased preablation s-Tg. ConclusionChildren and young adults younger than 20 years old with high-risk stratification and high neck uptake are likely to present a high level of preablation s-Tg after total thyroidectomy for papillary thyroid cancer. Continued long-term surveillance is necessary in this cohort of patients to confirm the role of preablation s-Tg as a biomarker for monitoring postoperative residual disease.

A Case Report of Water Intoxication During Radioactive Iodine Treatment: Why Physicians Should Communicate Clearly With Patients

Radioactive iodine (RAI) treatment is an effective method for the treatment of thyroid remnant ablation and metastasis in patients with differentiated thyroid cancer. The current guidelines recommend patients to drink lots of water to reduce the amount of iodine in the body during RAI treatment; however, water intoxication is a life-threatening condition resulting from hyponatremia. This case report describes water intoxication during RAI treatment in a 55-year-old patient who was evaluated for the management of angio-invasive follicular thyroid cancer following a total thyroidectomy. Hyponatremia is an electrolyte imbalance commonly encountered in oncology practice and is usually defined as a serum sodium level of less than 135 mEq/L. Water intoxication is a rare phenomenon that occurs due to an excessive intake of water, especially when the volume of water intake exceeds the excretory capacity of the kidney. This case report has revealed that all relevant information and instructions including the consumption of water should be clearly and accurately communicated to patients. J Endocrinol Metab. 2020;10(3-4):101-105 doi: https://doi.org/10.14740/jem646

No important salivary gland damage following radioiodine remnant ablation

No important salivary gland damage following radioiodine remnant ablation

The place of radioactive iodine remnant ablation in papillary thyroid microcarcinoma

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Preablative stimulated thyroglobulin in predicting dynamic risk stratification after 1 year in patients with differentiated thyroid cancer

The aimThe aim of the study is to establish the utility of stimulated preablative stimulated thyroglobulin (ps-Tg) as a predictor of response to therapy and to determine a possible cut-off for ps-Tg as prognostic tool. Patients and methodsA total of 73 consecutive patients who underwent total thyroidectomy and remnant ablation with radioactive iodine therapy (RIT) were reviewed retrospectively. Patients were classified according to the dynamic risk stratification 1 year after initial treatment. The ps-Tg values were compared among the groups. ROC curve analysis was performed. ResultsThe mean age at diagnosis was 43.85 (range: 17–75) with a female-to-male ratio of 4.6. Ps-Tg value after total thyroidectomy and before RIT ranged from 0,1 to 256ng/mL. When patients were restaged, 74% had excellent response to treatment, 12.3% indeterminate and 13.7% incomplete response 1 year after initial therapy. ROC curve analysis showed that the optimal cut-off for ps-Tg was 15ng/mL with a sensivity of 61%; a specificity of 87%; PPV of 61% and NPV of 87%. Among the group of patients showing an excellent response to treatment after 1 year, 87% had ps-Tg<15ng/mL. ConclusionPs-Tg before RIT is associated with dynamic risk stratification at 1 year after therapy in patients with DTC. Higher ps-Tg levels were found in patients that had indeterminate, and particularly incomplete, response.

Thyroid remnant ablation with radioiodine activity of 30, 60, and 100 mCi in patients with differentiated thyroid cancer - a prospective comparison of long-term outcomes.

IntroductionThe aim of this prospective study was to evaluate long-term outcomes in differentiated thyroid cancer (DTC) patients postoperatively treated with distinct RAI activities of 30 mCi, 60 mCi, and 100 mCi.Material and methodsThe analysis involved 277 low-risk and 46 intermediate-risk patients, who underwent radioiodine (RAI) ablation with 30 mCi, 60 mCi or 100 mCi under prospective, randomized clinical trials. Seventy-eight patients from the low-risk group received 30 mCi, whereas 125 and 74 patients received 60 mCi and 100 mCi, respectively. Regarding the intermediate-risk group, 20 patients were given 60 mCi, and 26 subjects were given 100 mCi. The mean time of follow-up was 11 years.ResultsAn excellent treatment response was obtained in 88%, 89% and 90% of low-risk patients treated with 30 mCi, 60 mCi, and 100 mCi, respectively, and in 85% of intermediate-risk patients, who were administered 60 or 100 mCi. An indeterminate response was achieved in 9.4% and 6.5%, whereas an incomplete structural response was obtained in 1.4% and 6.5% of low-risk and intermediate-risk patients, respectively. An incomplete biochemical response was observed only in 2.2% of intermediate-risk patients. The differences in treatment response regarding RAI activity were not significant.ConclusionsRAI activity of 30 mCi demonstrates a comparable efficacy as 60 mCi and 100 mCi in low-risk DTC. RAI activity of 60 mCi seems to be effective in intermediate-risk DTC.

Experiences of low iodine diets in the treatment of differentiated thyroid cancer with radioactive iodine ablation therapy.

International guidelines on the treatment of differentiated thyroid cancers (DTC) promote the use of low iodine diets (LID) prior to radioactive iodine remnant ablation (RIA), as high iodine status may interfere with radioiodine uptake. Most UK treatment centres adhere to these guidelines and advise people to consume a LID. There is limited research as to how people cope with the LID or its impact on daily life and wellbeing, and no studies have been conducted in the UK. This study explored peoples' views and experiences in relation to consuming a LID during treatment for DTC with RIA. Twenty-eight semi-structured interviews were conducted with people from across three treatment centres where differing advice had been delivered regarding a LID. Interviews were recorded, transcribed verbatim and key themes were developed through inductive thematic analyses. Individuals advised to consume a LID believed that adhering to the diet would help their treatment. Most restricted their diets beyond what was recommended and there was confusion surrounding what they could eat as part of the diet. Food selection and preparation were important which included substitution of foods and ingredient checking. Being on the diet was considered to have both a physical and psychological impact. The findings of this study provide a qualitative insight into the lived experiences of people with DTC in relation to consuming a LID. The results have relevance for professionals providing dietary guidance at oncology centres treating patients with RIA therapy in the UK.

Compartment syndrome of the leg after thyroid hormone withdrawal; two cases and a systematic review of the literature

BackgroundAcute compartment syndrome is a rare complication of severe hypothyroidism. If the symptoms are not recognized promptly and treatment initiated immediately, there is a high risk of permanent damage. Only few other cases of compartment syndrome due to hypothyroidism have been published and the exact pathophysiological mechanism remains unknown.Case presentationsA 59 year old male developed acute compartment syndrome of his right lower leg after thyroid hormone withdrawal prior to radioiodine remnant ablation after total thyroidectomy for follicular thyroid cancer. He underwent emergency fasciotomy of all four compartments of the lower leg. The muscle tissue in the anterior and lateral compartment was necrotic and was therefore excised. The second patient was a 62 year old female with Hashimoto’s thyroiditis, who developed acute compartment syndrome of both lower legs after thyroid hormone withdrawal due to non-compliance. Emergency fasciotomy of all four compartments of both legs was performed. The muscle tissue was viable in all compartments.ConclusionAlthough compartment syndrome due to hypothyroidism is uncommon, it is a complication physicians should be aware of. The majority of reported cases are caused by an acute withdrawal of thyroid hormones and not by undetected hypothyroidism. No previous case of compartment syndrome caused by an iatrogenic hormone withdrawal in preparation for radioactive iodine has been published. However, as shown in this report, it may be beneficial to inform patients of this rare complication prior to hormone withdrawal in preparation for remnant ablation after thyroidectomy.

Prognostic Implications of CD10 and CD15 Expression in Papillary Thyroid Carcinoma.

Patients with papillary thyroid carcinoma (PTC) have excellent survival, but recurrence remains a major problem in the management of PTC. We aimed to determine the prognostic impact of the expression of CD10 and CD15 in patients with PTC. Immunohistochemistry for CD10 and CD15 was performed on the tissue microarrays of 515 patients with PTC. The expression of CD10 and CD15 was detected in 201 (39.0%) and 295 (57.3%) of 515 PTC cases, respectively, but not in the adjacent benign thyroid tissue. Recurrence was inversely correlated with CD15 expression (p = 0.034) but not with CD10 expression. In 467 PTC patients treated with radioiodine remnant ablation, the CD15 expression had an adjusted hazard ratio of 0.500 (p = 0.024) for recurrence-free survival and an adjusted odds ratio of 2.678 (p = 0.015) for predicting long-term excellent therapeutic response. CD10 expression was not associated with clinical outcomes. In the Cancer Genome Atlas dataset, the expression level of FUT4 (CD15) mRNA was higher in the low/intermediate-risk group for recurrence than in the high-risk group and exhibited positive correlation with SLC5A5 (NIS) mRNA expression (p = 0.003). Taken together, CD15 expression was identified as an independent prognostic marker for improved prognosis in PTC patients.

Contemporary considerations in adjuvant radioiodine treatment of adults with differentiated thyroid cancer.

Differentiated thyroid cancer (DTC) is the most common endocrine malignancy with a growing incidence worldwide. The initial conventional management is surgery, followed by consideration of 131 I treatment that includes three options. These are termed remnant ablation (targeting benign thyroid remnant), adjuvant (targeting presumed microscopic DTC) and known disease (targeting macroscopic DTC) treatments. Some experts mostly rely on clinicopathologic assessment for recurrence risk to select patients for the 131 I treatment. Others, in addition, apply radioiodine imaging to guide their treatment planning, termed theranostics (aka theragnostics or radiotheragnostics). In patients with low-risk DTC, remnant ablation rather than adjuvant treatment is generally recommended and, in this setting, the ATA recommends a low 131 I activity. 131 I adjuvant treatment is universally recommended in patients with high-risk DTC (a primary tumor of any size with gross extrathyroidal extension) and is generally recommended in intermediate-risk DTC (primary tumor >4 cm in diameter, locoregional metastases, microscopic extrathyroidal extension, aggressive histology or vascular invasion). The optimal amount of 131 I activity for adjuvant treatment is controversial, but experts reached a consensus that the 131 I activity should be greater than that for remnant ablation. The main obstacles to establishing timely evidence through randomized clinical trials for 131 I therapy include years-to-decades delay in recurrence and low disease-specific mortality. This mini-review is intended to update oncologists on the most recent clinical, pathologic, laboratory and imaging variables, as well as on the current 131 I therapy-related definitions and management paradigms, which should optimally equip them for individualized patient guidance and treatment.

Indication for radioiodine remnant ablation in differentiated thyroid cancer patients: does 2018 Italian consensus change anything?

We speculated that radioiodine remnant ablation (RRA) could be performed less frequently in differentiated thyroid cancer (DTC) patients, if the recommendations of the 2018 Italian Consensus (ITA) were applied in clinical practice. Therefore, we compared the ITA indications for RRA with the recommendations by the 2015 American Thyroid Association guidelines (ATA). We retrospectively evaluated 380 consecutive DTC patients treated with surgery and RRA, followed at the Section of Endocrinology, University of Siena, Italy from January 2006 to December 2019. Using ITA a significant increase of DTC patients classified as low or high risk and a significant decrease of patients defined at intermediate risk were observed (p < 0.0001). Consequently, the percentage of patients without routinary indication for RRA (47.4%, versus 38.2%, p < 0.0001) and those with a definite indication for RRA (8.2 versus 1.8%, p < 0.0001) was significantly higher compared to ATA. Moreover, using ITA the percentage of patients with a selective use of RRA was lower in comparison to ATA (44.7% versus 60%, p < 0.0001). Nevertheless, the prevalence of distant metastases, at post-ablative whole body scan, in patients without indication for RRA, was not different using either ATA or ITA (2.1% and 1.1% respectively, p = 0.37). The use of ITA Consensus, in clinical practice, increases significantly the number of patients for whom RRA is not routinely indicated in comparison to ATA guidelines but without differences in delaying the diagnosis of distant metastatic disease.

MON-494 Quality of Life in Patients with Papillary Thyroid Microcarcinoma According to the Treatment: Total Thyroidectomy Versus Total Thyroidectomy with Radioactive Iodine Remnant Ablation

Background: Recently, the role of radioactive iodine (RAI) ablation in the treatment of low risk differentiated thyroid carcinoma (DTC), especially for papillary thyroid microcarcinoma (PTMC), is controversial. This study aims to compare quality of life (QoL) parameters in patients with PTMC underwent total thyroidectomy (TT) versus TT with RAI ablation. Methods: In this cross-sectional study, patients with PTMC who underwent TT with/without RAI remnant ablation were prospectively enrolled between June 2016 and October 2017. All patients completed three questionnaires: 12-item short-form health survey (SF-12), thyroid cancer specific quality of life (THYCA-QOL), and fear of progression (FoP). Results: The TT and TT with RAI groups comprised 107 and 183 patients, respectively. The TT with RAI group had significantly lower serum TSH level than TT group. However, after matching of TSH level between the groups (TT with RAI = 100, TT = 100), there was no significant difference in baseline characteristics. According to the SF-12, the score for general health showed significantly lower in TT with RAI group than TT group (p = 0.047). The THYCA-QOL also showed statistically significant difference in felt chilly score between the groups (p = 0.023). No significant differences in FoP scores were seen between the groups. Conclusion: Patients with PTMC underwent TT with RAI ablation experienced more health-related problems than those managed by TT alone. These findings support RAI ablation should be carefully determined in patients with low-risk DTCs.

MON-453 Dramatic Clinical Response to Lenvatinib in a Pediatric Patient with Advanced Metastatic Papillary Thyroid Carcinoma

Introduction: Papillary thyroid cancer (PTC) is the most common thyroid tumor in childhood. Most patients are referred with locally advanced and/or distant disease at the time of diagnosis. Whenever possible, these patients should be offered total thyroidectomy and radioiodine remnant ablation; however, this approach is not always feasible, rendering these tumors unresectable. These critical cases could benefit from neoadjuvant treatment with multikinase inhibitors (MKI) so that standard treatment can be performed. Lenvatinib is an MKI recently approved in many countries throughout the world for the treatment of radioiodine refractory adult differentiated thyroid cancer. Only few pediatric cases have been reported. Case report: A 10-year-old female patient with locally advanced PTC and metastasis to the lungs, who required 3 liters of oxygen due to respiratory failure caused by bilateral miliary lung disease, mistakenly treated as tuberculosis two months previously and referred to our Hospital. A large thyroid mass adhered to deep tissues was confirmed on CT scan, showing a large heterogeneous neck mass with multiple microcalcifications associated with multiple lymph nodes. Both lungs had multiple micro-nodular disease with interstitial involvement. Total thyroidectomy together with lymph-node dissection was planned, but extensive local infiltration made the lesion unresectable and surgery was limited to a thyroid biopsy. The patient required respiratory assistance. Histopathology confirmed the presence of a PTC (diffuse sclerosing variant) with a RET-PTC3 oncogene rearrangement. Eight days after surgery the patient was critical and we decided to indicate the compassionate use of Lenvatinib. The patient was started on oral lenvatinib at a dose of 14 mg daily (14 mg/m/day). Three days later, she clinically improved and nine days post-lenvatinib initiation, the patient was discharged from hospital without need for oxygen therapy. Lab studies showed a rise in thyroglobulin levels in the first month of treatment followed by a significant drop. All Lung Function Test parameters significantly improved. The patient initially had severe restrictive breathing and due to the resting dyspnea with hypoxemia she could not perform the walking test. Two months after treatment onset she could walk 360 meters in six minutes with 96% oxygen saturation. After 4 months on Lenvatinib, imaging studies showed a stable thyroid mass while the pulmonary nodules appeared stable to slightly smaller without evidence of new or progressive disease. Conclusion: On lenvatinib treatment, our patient showed significant clinical improvement, arrest of disease progression, and stable disease on imaging studies. This case shows that lenvatinib may be a beneficial option for children with advanced PTC not amenable to surgery/RAI treatment and may be used as a bridge to these first-line therapies.

Referral Practice for Radioactive Iodine Ablation (RAI) after ATAguidelines 2015: results from a Tertiary Cancer Care Centre.

The ATA guidelines for differentiated thyroid cancer (DTC) are one of the most widely referred to. Their 2015 edition proposed a new risk stratification system and modified the indications for radioactive iodine (RAI) ablation especially for the low risk category. We attempted to analyze whether the new guidelines altered referral practices for RAI ablation at our institute. Patients who underwent total or completion thyroidectomy for DTC during 2016-2017 were included. Relevant demographical and pathological data was tabulated. Patients were classified as per the new stratification system and referral practice for RAI ablation documented. 238 patients were included. Of these 20.6% were low risk, 44.1% were intermediate and 35.3% were high risk as per modified guidelines. All patients within the intermediate and high-risk group and 77.8% of the low risk group were referred for RAI ablation. Analysis of risk factors revealed that within the low risk group there were three patients with < 5 metastatic nodes, all within 3cm in size-a category that the ATA failed to stratify appropriately. Among those labeled as Intermediate risk due to microscopic extra thyroidal extension (ETE), 85% had no other risk factors and were upstaged solely due to microscopic ETE, which is interestingly no longer included in the TNM staging. Majority of low risk patients continue to receive RAI ablation due to persistent belief emanating from literature that remnant ablation improves outcomes and aids in follow up. The issue of RAI ablation for low risk group and prognostic implications of microscopic ETE and limited nodal disease need to be revisited.

Scintigraphic evaluation of salivary gland function in thyroid cancer patients after radioiodine remnant ablation.

Radioiodine (131I, RAI) has traditionally been used in thyroid cancer treatment but its benefit should be balanced against possible risks. Among them, salivary gland dysfunction has often been discussed, although the reported data have been inconsistent. The aim of our prospective study was to evaluate salivary gland function in 31 thyroidectomised patients (6 men, 25 women; median age 52 yr) before and 4–6 months after RAI remnant ablation (RRA), using activity of 3.7 GBq 131I‐NaI. Salivary gland uptake and excretion fractions were quantitatively assessed with 99mTc – pertechnetate salivary gland scintigraphy. Pre‐ and post‐treatment values were compared using Wilcoxon signed rank test. No statistically significant difference in the pre‐ and post‐treatment values was observed in parotid or submandibular glands uptake, or in the parotid or submandibular excretion fractions. The calculated power for minimum relevant difference of 25% with the sample size of 31 ranged between 86% and 96% for the individual variables, making our negative results reasonably reliable. The results suggest that RRA with the most commonly used activity of 3.7 GBq has no important impact on salivary gland function. Therefore, the concerns about putative salivary gland functional deterioration following RRA are probably unjustified.

Recombinant human thyrotropin versus thyroid hormone withdrawal in an Asian population

To prepare for radioactive iodine therapy in post total thyroidectomy patients with well-differentiated thyroid cancer (WDTC), either thyroid hormone withdrawal (THW) or administration of recombinant human thyrotropin (rhTSH) can be performed. Our objective is to compare quality of life (QoL) parameters using the SF-36v2 questionnaire (Short Form health survey) and a self-evaluated item, and the hypothyroid status using modified Billewicz scores in an Asian population undergoing either THW or rhTSH for remnant ablation or adjuvant treatment following total thyroidectomy for WDTC. We will also assess the proportion of patients achieving TSH level of >30 mU/L after 4 weeks of thyroid hormone withdrawal. Patients in the rhTSH group were better in the QoL domains of physical functioning, role functioning/physical and bodily pain, while patients in THW group were better in mental health. This was however, not statistically significant. Modified Billewicz scores were higher in patients in THW group as compared with rhTSH group and statistically significant. A total of 96.3% of patients achieved TSH level >30 mU/L after 4 weeks of THW. Clinical symptoms and signs of hypothyroidism as assessed with modified Billewicz scores were statistically significantly higher in the THW group. However, there was no statistically significant difference in QoL in the rhTSH group.

Positive Lymph Node Counts in American Thyroid Association Low-Risk Papillary Thyroid Carcinoma Patients.

Current American Thyroid Association (ATA) guidelines state that patients with intermediate-risk papillary thyroid cancer (PTC) may benefit from remnant ablation. One criterion for intermediate-risk classification is >5 positive lymph nodes (LNs). We investigate whether performing step-sectioning of LNs increases the metastatic detection rate, thereby influencing ATA risk of recurrence (ROR) classification. A retrospective review was conducted of cases in which ≥ 5 LNs were removed during thyroidectomy and ≤5 LNs were found positive for PTC. Step-sectioning was performed on the original tissue blocks. All slides were re-reviewed by a senior pathologist. Twenty patients met study criteria. Step-sectioning significantly increased LN yield compared to standard sectioning. In total, we found 12 new positive lymph nodes; seven (58%) were in totally new lymph nodes, while five (42%) were in lymph nodes previously read as negative. All newly discovered metastases were classified as micrometastases (≤2mm). Of the 15 patients originally classified as low-risk, the step-sectioning protocol impacted two patients (13%), increasing ROR stratification. Intensive step-sectioning reveals additional micrometastases. More detailed analysis did not identify clinically significant nodal disease likely to impact the clinical course of patients in this study. Our study supports current standards of pathology specimen handling related to LN assessment and the impact on ATA ROR classification. Nonetheless, it is important for clinicians to understand their institution's sectioning protocol utilized to report positive and total LN counts, which could impact ATA risk stratification and denote the comprehensive nature of the LN dissection that was performed.

Prognostic value of post-ablation 131 I scintigraphy in children with thyroid cancer.

To evaluate the prognostic value of post-ablation whole-body scintigraphy (PAS) in children with thyroid cancer following 131 I therapy. A retrospective analysis of children with thyroid cancer who underwent remnant ablation was performed. PAS results were correlated with clinical and histopathologic characteristics of the primary tumor and compared with the follow-up data. One hundred and sixty-eight children were eligible for the analysis. The median age was 17 years, and the majority were female (81.5%). In multivariate analysis, N1b classification and 131 I ablative dose were associated with PAS positivity. After a median follow-up of 49 months, 89 (71.8%) of 124 children with normal PAS achieved complete remission. Fifteen of 44 (34.1%) children with positive PAS had complete remission. Kaplan-Meier analysis showed that positive PAS was negatively associated with cumulative complete remission rates (P < .001). PAS could provide prognostic information in children with thyroid cancer undergoing 131 I therapy.

Cómo es de importante el momento de la ablación con radioyodo en los carcinomas diferenciados de tiroides: la experiencia de un centro de referencia

IntroductionIt's difficult to make a scientific, evidence-based approach about the timing of radioiodine remnant ablation (RRA) in patients with differentiated thyroid carcinomas (DTCs). Primary aim of the study was to reveal whether timing of RRA relates to achievement of non- structurally incomplete response (non-SIR) in low/intermediate and high-risk patients. Another aim was to reveal the correlation of timing with non-SIR status in reproductive-age women. Materials and MethodsRecords of 279 low, intermediate, and high-risk patients were analysed, retrospectively. Number of days between surgery and RRA is referred to as timing. Low/intermediate-risk patients, high-risk patients, and low/intermediate-risk reproductive-age women were divided into non-SIR and SIR groups, according to 2015 American Thyroid Association guidelines for therapy response. The relationship between timing and therapy response was analysed statistically. ResultsWe could not find any significant relationship in patients with low/intermediate risk between timing and non-SIR, including women between 18-49 years of age (p >0.1). For high-risk patients, we found a statistically significant relationship between timing and non-SIR response. According to ROC analysis, RRA ≤58 days was found as a cut-off value. The sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio were calculated as 83.3%, 70.0%, 2.78, and 0.24, respectively. ConclusionRRA must be initiated within 58 days after surgery in patients with high-risk DTCs. Under this approach, risk of SIR and associated mortality risk may be reduced. RRA timing for women in reproductive ages with low/intermediate risk groups may be planned according to their pregnancy/breastfeeding intent. For other low/intermediate risk groups, they can safely proceed according to the capacity of the medical facility and related logistical considerations.

Short-term bone marrow suppression in differentiated thyroid cancer patients after radioactive iodine treatment.

After thyroidectomy in differentiated thyroid cancer (DTC), radioactive iodine (RAI) treatment is often used for remnant ablation. However, RAI treatment has been associated with bone marrow suppression, and leukopenia, anemia, and thrombocytopenia may occur after a single RAI administration. In this study, we examined the change in complete blood counts at 1 week after RAI administration; this is less well studied. A group of 189 DTC patients who received RAI treatment and underwent blood tests before and after treatment, were included. Peripheral blood counts at baseline were compared to those obtained at 1 week, 1-6 months, and 6-12 months after RAI treatment in order to test for bone marrow suppression. At 1 week after RAI treatment, there was a significant decrease in the white blood cell count (WBC, 5.8 ± 1.6 × 109/L vs. 5.4 ± 1.5 × 109/L, p < 0.001) and hemoglobin level (Hb, 13.5 ± 1.7 g/dL vs. 13.3 ± 1.4 g/dL, p = 0.001). The WBC decrease was mostly due to lymphocyte counts (2.2 ± 0.6 × 109/L vs. 1.6 ± 0.5 × 109/L, p < 0.001), with no decrease in the neutrophil count. Although not significantly changed at 1 week, platelets counts were altered within 6 months (265 ± 69 × 109/L vs. 239 ± 53 × 109/L, p < 0.001). The decline in the WBC count recovered within 6 months; lymphocyte and platelet counts recovered within 12 months. In conclusion, RAI treatment after a thyroidectomy was associated with a statistically significant but temporary decline in WBC counts and Hb levels at 1 week. Physicians treating DTC patients should not decrease usage of moderate dose RAI treatments.