Impact of radioiodine therapy on recurrence and survival outcomes in intermediate-risk papillary thyroid carcinoma -A systematic review and meta-analysis.

OBJECTIVE: The utility of radioiodine (RAI) therapy in intermediate-risk papillary thyroid carcinoma (PTC) remains a topic of ongoing discussion. This systematic review and meta-analysis aimed to consolidate existing evidence on the impact of postoperative RAI therapy on recurrence and survival outcomes in intermediate-risk PTC. METHODS: A literature search was performed using relevant keywords in PubMed, Scopus, and EMBASE. Articles from January 2008 to March 2023 were included. Odds ratios (ORs) and hazard ratios (HRs) were extracted from the individual articles, and pooled estimates were generated using meta-analysis. RESULTS: Eleven articles comprising 56,266 intermediate-risk PTC patients were included. 41,530 (73.8%) patients underwent postoperative RAI therapy, while 14,736 (26.2%) patients were kept on no-RAI (NOI) follow-up. No significant reduction in rates of structural disease recurrence was noted with RAI therapy in comparison to NOI follow-up (pooled univariate OR, 0.73, 95% confidence interval [CI], 0.29-1.87, I2 = 75%). RAI therapy was not a significant predictor of better recurrence-free survival (pooled multivariate HR, 0.21; 95% CI, 0.01-3.74, I2 = 94%). Interestingly, RAI therapy was associated with an overall survival benefit compared to NOI follow-up (pooled multivariate HR, 0.63; 95% CI, 0.48-0.82, I2 = 79%). CONCLUSIONS: This meta-analysis did not establish a conclusive benefit of RAI therapy in preventing structural disease recurrence or improving recurrence-free survival in intermediate-risk PTC. However, these results need to be interpreted with caution owing to significant heterogeneity in the existing literature. A prospective, randomised clinical trial is the need of the hour to better understand the effect of RAI therapy on long-term outcomes.

Effect of Radioactive Iodine Therapy on Cancer-Specific Survival of Papillary Thyroid Cancer Tall Cell Variant.

CONTEXT: Radioactive iodine (RAI) therapy is often used as an adjuvant treatment to reduce the risk of recurrence in patients with papillary thyroid cancer (PTC). However, the effect of RAI therapy on cancer-specific survival (CSS) in patients with tall cell variant (TCV) remains controversial. OBJECTIVE: This study aimed to investigate the impact of RAI therapy on CSS in patients with TCV-PTC by analyzing data from the Surveillance, Epidemiology, and End Results database. METHODS: We identified 1281 patients with TCV-PTC in the SEER database who underwent total thyroidectomy between 2004 and 2019. Of these, 866 (67.6%) patients received RAI therapy and 415 (32.4%) did not. Propensity score matching was conducted to balance the baseline characteristics between the 2 groups. Cox proportional hazards regression models were used to estimate the hazard ratio (HR) and 95% CI for the effect of RAI therapy on CSS. RESULTS: After propensity score matching, 373 pairs of patients were included in the analysis. The results showed no significant difference in CSS between the RAI therapy group and the non-RAI therapy group (HR 0.54, 95% CI 0.25-1.17, P = .120). Subgroup analyses indicated similar results. CONCLUSION: RAI therapy may not improve CSS in patients with TCV-PTC after total thyroidectomy. Future studies with larger sample sizes, longer follow-up periods, and better study designs are needed to confirm or refine our research findings.

Guiding the postoperative radioactive iodine-131 therapy for patients with papillary thyroid carcinoma according to the prognostic risk groups: a SEER-based study.

PURPOSE: The effectiveness of iodine-131(131I) therapy in patients with papillary thyroid cancer (PTC) of various stage is controversial. This study aimed to use prognostic risk groups to guide 131I therapy in patients with PTC after radical thyroidectomy. METHODS: Data of 53,484 patients with PTC after radical thyroidectomy were collected from the Epidemiology and End Results (SEER) database. Patients were divided into subgroups according to MACIS system and regional lymph node involvement. The prognostic role of 131I therapy was investigated by comparing Kaplan-Meier survival analysis and Cox proportional hazard models in different subgroups. RESULTS: Sex, age, tumor size, invasion, regional lymph node involvement, and distant metastasis was related to the survival of patients with PTC. If MACIS < 7, 131I treatment didn't affect the cancer-specific survival (CSS) rate. If MACIS ≥ 7, 131I therapy didn't work on CSS rate for patients with N0 or N1a < 5 status; 131I therapy had improved CSS rate for patients in the N1a ≥ 5 or N1b status. If patients with distant metastasis, invasion, or large tumor, 131I therapy didn't improve CSS rate for patients in N0 or N1a < 5 stage. CONCLUSION: After radical thyroidectomy, if MACIS < 7, patients with PTC could avoid 131I therapy. If MACIS ≥ 7, patients in the N0 or N1a < 5 could avoid 131I therapy; those in the N1a ≥ 5 or N1b stage should be given 131I therapy. Among them, all patients with distant metastasis should be given 131I therapy.

Factors Affecting Ablation Success After I-131 Radioactive Iodine Therapy in Low and Intermediate Risk Papillary Thyroid Cancer.

The study was to evaluate the effect of radioactive iodine (RAI) treatment application time and clinical, histopathological factors on ablation success in patients with operated papillary thyroid cancer (PTC) in low and intermediate-risk. One hundred sixty-one patients with PTC in the low and intermediate-risk were evaluated. Most patients (89.4%) were in the low-risk, and 10.6% were in the intermediate-risk. When the patients were divided into two groups according to the date of receiving RAI treatment after surgery, those who received early treatment (≤3 months) constituted the majority of the patients (72.7%). Seventeen patients received 1.85 Gigabecquerel (GBq), 119 3.7 GBq, 25 5.55 GBq RAI. Most patients (82%) achieved ablation success after the first RAI treatment. The time interval between surgery and RAI treatment did not affect ablation success. Stimulated Tg level measured on the RAI treatment day was an independent predictive factor for successful ablation (p<0.001). The cut-off value of Tg found to predict ablation failure was 5.86 ng/ml. It was concluded that 5.55 GBq RAI treatment could predict ablation success compared to 1.85 GBq dose (p=0.017). It was concluded that having a T1 tumor may predict treatment success compared to a T2 or T3 tumor (p=0.001, p<0.001, retrospectively). The time interval does not affect ablation success in low and intermediate-risk PTC. The ablation success rate may decrease in patients who receive low-dose RAI and have high Tg levels before treatment. The most crucial factor in achieving ablation success is giving enough doses of RAI to ablate the residual tissue.

Effect of Waiting Time for Radioactive Iodine Therapy on Outcome in N1 Stage Papillary Thyroid Cancer.

CONTEXT: The waiting time for radioactive iodine therapy (WRAIT) after total thyroidectomy (TT) in patients with papillary thyroid cancer (PTC) and lymph node metastases (N1) has not been sufficiently investigated for risk of adverse outcomes. OBJECTIVE: This work aimed to estimate the effect of WRAIT on the outcomes of disease persistence and recurrence among patients with N1 PTC and investigate factors predictive of delayed radioactive iodine therapy (RAIT). METHODS: This retrospective cohort study was conducted in a university hospital. A total of 909 patients with N1 PTC were referred for RAIT between 2014 and 2018. WRAIT is the duration between TT and initial RAIT. The optimal WRAIT threshold determined using recursive partitioning analysis was used to define early and delayed RAIT. The primary end point was tumor persistence/recurrence. We compared the outcomes of patients with early and delayed RAIT using inverse probability weighting based on the propensity score. RESULTS: The WRAIT threshold that optimally differentiated worse long-term remission/excellent response outcomes was greater than 88 days (51% of our cohort; n = 464). WRAIT exceeding 88 days was associated with an augmented risk of disease persistence/recurrence (odds ratio, 2.47; 95% CI, 1.60-3.82) after adjustment. Predictors of delayed RAIT included residence in lower-income areas, reoperation before the initial RAIT, TT at a nonuniversity-affiliated hospital, multifocality, extrathyroidal extension, N1b disease, and pre-RAIT-stimulated thyroglobulin level less than 1 ng/mL. CONCLUSION: Delayed RAIT beyond 88 days after TT in patients with N1 PTC independently increased the risk of disease persistence/recurrence. Evaluation of the predictive determinants of prolonged WRAIT may help target at-risk patients and facilitate interventions.

The role of BRAF V600E mutation in post-surgical 131I therapy in papillary thyroid carcinoma: a study based on SPECT-CT uptake analysis.

BACKGROUND: The BRAF V600E mutation (BRAF mut) in papillary thyroid cancer (PTC) has been associated with poor response to therapy with 131I in patients with metastases but the results in postsurgical treatment are controversial. Our main objective is to investigate the impact of the mutation on the biokinetics of the administered 131I therapy after surgery. METHODS: A prospective study was designed, from July 2015 to January 2018 which included patients with PTC receiving 131I therapy after surgical treatment. To study the biokinetics of the radioiodine in postoperative thyroid remnants, SPECT-CT images were acquired so as to obtain the following variables: percentage of remnant uptake at 2 and 7 days post-administration, effective half-life and time-integrated activity coefficient. All of them were compared depending on the mutational diagnosis and other clinical features and pathological variables. RESULTS: Sixty-one patients, and in total 103 thyroid remnants, were included. About 59% of patients were BRAF mutated. The mutation was associated with classic variant (88.5% vs. 11.5%; P=0.0001), desmoplastic reaction (85.7% vs. 14.3%; P=0.002), smaller tumor size (1.5 vs. 2.1 cm; P=0.024), nodal disease (3.3 vs. 1; P=0.001) and advanced stages (76.9% vs. 23%; P=0.014). The BRAFmut group had a lower percentage of 131I uptake at 2 days (0.17% vs. 0.47%; P=0.001) and at 7 days (0.02% vs. 0.1%; P=0.013); and a lower time-integrated activity coefficient (0.05h vs. 0.17 h; P=0.002). In univariate analysis, in addition to the mutation, the histological variant was significant but only for time-integrated activity coefficient (P=0.04). In multivariate analysis, only mutation determined the 2-day uptake (P<0.001) and the time-integrated activity coefficient (P<0.001). CONCLUSIONS: The BRAF V600E mutation is associated with lower 131I uptake in thyroid remnants. Furthermore, it is an independent factor that decreases the effect of post-surgical 131I therapy, and therefore, it could be used as a potential tool to optimize the treatment of PTC.

Role of 131I in low-risk differentiated thyroid cancer.

Differentiated thyroid cancer (DTC) is the most frequent endocrine neoplasm, with an increase in recent decades. Papillary carcinoma is the most frequent histological subtype and a large number of cases are related to tumors of small size and with little clinical repercussion, detected incidentally or as a consequence of the availability of diagnostic techniques. The "good prognosis" of the majority of cases has maintained for years the controversy in the approach to these patients, especially in two basic aspects of the therapeutic protocol: surgery and the administration of radioiodine. While in metastatic and high-risk patients, the administration of 131I therapy is widely accepted, in intermediate-low risk patients its use is highly questioned. In this paper we review the available evidence on radioiodine therapy in low-risk patients.

Oncological outcomes for encapsulated papillary carcinoma of the breast: Multicentric study of Turkish Society for Radiation Oncology breast cancer study group (TROD 06-014 study).

BACKGROUND: Encapsulated papillary carcinoma (EPC) is a rare malignant papillary breast cancer accounting for approximately .5%-2% of all breast tumors. The aim of this multicenter study was to evaluate clinicopathologic features of EPC in addition to oncological outcomes and radiotherapy (RT) details. METHODS: From 10 different academic hospitals in Turkey, we obtained pathology reports of 80 patients with histologically confirmed EPC between 2005 and 2022. Demographic, diagnostic, and treatment data were collected from medical records, retrospectively. Local failure, distant progression, toxicity-adverse effects, overall survival (OS), and disease-free survival were evaluated, and survival analyzes were performed using the Kaplan-Meier method. RESULTS: Eighty patients with the diagnosis of misspelled sorry (ECP) were retrospectively evaluated. The median age of the patients was 63 (range, 35-85). After a median follow-up of 48 (range; 6-206) months, local recurrence was observed in three patients (4%). Local recurrence was less common in the patients who received whole breast RT with a tumour bed boost (p = .025). There were not any distant metastasis or disease-related death. RT was applied to 61% of the cases, and no treatment-related grade 3 or higher toxicity was reported in any of the patients. Five year OS, cancer-specific survival (CSS), and  were observed as 85%, 100%, and 96%, respectively. CONCLUSIONS: ECP is a rare, slow-progressing breast carcinoma associated with good prognosis, it is a disease of elderly patient, and usually occurs in postmenopausal women. It responds extremely well to optimal local treatments and appropriate adjuvant treatments on a patient basis, and has excellent OS and CSS ratios.

Long-term clinical outcomes and prognostic factors for patients with papillary thyroid carcinoma with other organ invasions after adjuvant radioactive iodine.

PURPOSE: Papillary thyroid carcinoma (PTC) with other organ invasions is directly related to patient prognosis and quality of life; however, studies on the clinical outcomes of adjuvant radioactive iodine (RAI) for PTC with other organ invasions are limited. This study aimed to clarify the clinical outcomes and prognostic factors for patients with PTC with other organ invasions after adjuvant RAI. METHODS: Patients with PTC with other organ invasions without distant metastases who underwent surgery and adjuvant RAI were retrospectively reviewed. We evaluated the initial responses based on the American Thyroid Association guidelines and survival rates. Prognostic factors for locoregional recurrence-free survival (LRRFS) were analyzed. RESULTS: Between January 2005 and December 2019, 102 patients were included in the study. Their median age was 55 years. The median follow-up duration was 92 months (range; 30-231 months). The excellent response rate after RAI was 42%. The 7-year overall survival, LRRFS, and recurrence-free survival rates were 100%, 75%, and 75%, respectively. Metastatic lymph node size, resection margin status, and post-RAI suppressed thyroglobulin level were the independent prognostic factors for LRRFS. CONCLUSION: We demonstrated that 75% of patients with PTC with other organ invasions could achieve long-term survival without recurrence after adjuvant RAI. Future development of effective treatment strategies for large metastatic lymph nodes, gross residual tumors, and high serum thyroglobulin levels is warranted.

Analysis of factors influencing the clinical outcome after surgery and 131I therapy in patients with moderate-risk thyroid papillary carcinoma.

Purpose: Generally, the prognosis for papillary thyroid cancer (PTC) is favorable. However, the moderate risk involved warrants further evaluation. Hence, we investigated the clinical outcomes in patients with moderate-risk PTC following surgery and the first 131I therapy, as well as the relevant factors that influence the therapeutic efficacy. Methods: Retrospective analyses of 175 patients with medium-risk PTC who visited the Second Affiliated Hospital of Chongqing Medical University from September 2017 to April 2019 were conducted. In according with the 2015 American Thyroid Association (ATA) guideline treatment response evaluation system, the patients were categorized into the following groups: excellent response (ER), indeterminate response (IDR), biochemical incomplete response (BIR), and structurally incomplete response (SIR), of which IDR, BIR, and SIR were collectively referred to as the NER group. To compare the general clinical features between the 2 groups of patients, 2 independent samples t-tests, χ2 test, and Mann-Whitney U-test were performed, followed by multivariate logistic regression analyses. With reference to the receiver operating characteristic (ROC) curve, the predicted value of ps-Tg to ER was evaluated, and the best cut-off value was determined. The subgroups with BRAFV600E test results were analyzed by χ2 test only. Results: The treatment responses of 123 patients were ER, while those of 52 patients were NER. The differences in the maximum tumor diameter (U = 2495.50), the amount of metastatic lymph nodes (U = 2313.50), the size of metastatic lymph node (U = 2113.50), the metastatic lymph node ratio (U = 2111.50), metastatic lymph node location (χ2 = 9.20), and ps-Tg level (U = 1011.00) were statistically significant. Multivariate regression analysis revealed that ps-Tg (OR = 1.209, 95% CI: 1.120-1.305) was an independent variable affecting ER. The cut-off value of ps-Tg for predicting ER was 6.915 ug/L, while its sensitivity and specificity were 69.2% and 89.4%, respectively. Conclusions: Patients with smaller tumor size, fewer lymph nodes, lower metastatic lymph node ratio, metastatic lymph nodes in the central region, smaller lymph node size, and ps-Tg <6.915 ug/L demonstrated better therapeutic effects after the initial treatment.

The high degree of similarity in histopathological and clinical characteristics between radiogenic and sporadic papillary thyroid microcarcinomas in young patients.

The potential overtreatment of patients with papillary thyroid microcarcinoma (MPTC) has been an important clinical problem in endocrine oncology over the past decade. At the same time, current clinical guidelines tend to consider prior radiation exposure as a contraindication to less extensive surgery, even for low-risk thyroid carcinomas, which primarily include microcarcinomas. This study aims to determine whether there are differences in the behavior of MPTC of two etiological forms (radiogenic and sporadic), including invasive properties, clinical data, and recurrence in patients aged up to 30 years. For this purpose, 136 radiogenic (from patients aged up to 18 years at the time of the Chornobyl accident) and 83 sporadic (from patients born after the Chornobyl accident) MPTCs were selected and compared using univariate and multivariate statistical methods in a whole group and in age and tumor size subgroups. No evidence of more aggressive clinical and histopathological behavior of radiogenic MPTCs as compared to sporadic tumors for basic structural, invasive characteristics, treatment options, and postoperative follow-up results was found. Moreover, radiogenic MPTCs were characterized by the lower frequencies of oncocytic changes (OR = 0.392, p = 0.004), nodal disease (OR = 0.509, p = 0.050), and more frequent complete remission (excellent response) after radioiodine therapy (OR = 9.174, p = 0.008). These results strongly suggest that internal irradiation does not affect tumor phenotype, does not associate with more pronounced invasive properties, and does not worsen prognosis in pediatric or young adult patients with MPTC, implying that radiation history may be not a pivotal factor for determining treatment strategy in such patients.

Potential Impact of Body Mass Index on the Clinical Outcome of Papillary Thyroid Cancer After High-Dose Radioactive Iodine Therapy.

Context: Obesity has been reported as a potential risk factor for the aggressiveness of papillary thyroid cancer (PTC), but the data gathered so far are conflicting. Objective: The aim of our study was to evaluate the relationship between body mass index (BMI) and aggressiveness of PTC at the diagnosis and clinical outcome. Methods: A total of 337 patients who underwent radioactive iodine (RAI) therapy between March 2017 and May 2020 were recruited. Patients were divided into four groups: underweight (BMI<18.5 kg/m2), normal weight (18.5-24.9 kg/m2), overweight (25-29.9 kg/m2), and obese (BMI≥ 30 kg/m2). Treatment and follow-up were defined according to criteria used in the 2015 ATA guidelines. Results: This study included 337 patients with PTC (71.5% women, median age 45.21 ± 13.04 years). The mean BMI was 24.2 ± 3.1 kg/m2. Obese groups had a higher age than the other groups (P = 0.001). Moreover, obese patients had larger tumor sizes and higher T stage, compared to overweight, normal weight, and underweight patients (P = 0.007). After a median follow-up of 32 months, 279 patients (82.7%) had achieved an excellent response (ER) to therapy. The overall ER rates were compared between groups, and they did not differ significantly. Conclusions: We demonstrated that BMI may have an additive effect on the aggressiveness of PTC, but did not have an effect on the response to therapy after high-dose RAI therapy.

Radiation-induced synchronous mandibular osteosarcoma and papillary thyroid carcinoma: A disguised conundrum.

With substantial improvement in survival in cancer patients, the risk of radiation-induced malignancy in previously irradiated areas is increasingly possible. Both radiation-induced sarcomas and papillary thyroid carcinomas (PTCs) are well documented in literature. However, radiation-induced synchronous malignancies are rare, are often misdiagnosed, and presents with diagnostic and therapeutic challenges due to paucity of literature and lack of available guidelines. Here, we report a case of radiation-induced synchronous mandibular osteosarcoma and PTC in a previously treated carcinoma of base tongue with concurrent chemoradiation. He initially presented with an oral cavity mass, and during the course of the treatment was incidentally diagnosed with a synchronous PTC. It also establishes the indolent course of PTC, which often goes undiagnosed till the presentation with regional nodal metastasis. This report, to the best of our knowledge, is the first reported case of synchronous radiation-induced OSM and PTC.

Clinical Effects of Microwave Ablation in the Treatment of Low-Risk Papillary Thyroid Microcarcinomas and Related Histopathological Changes.

Objective: This study aimed to evaluate the feasibility and efficacy of ultrasound-guided percutaneous microwave ablation (MWA) in the treatment of low-risk papillary thyroid microcarcinoma (PTMC), and to observe the histopathological changes after MWA. Methods: MWA was performed under ultrasound guidance for 73 unifocal PTMC patients without clinically cervical or distant metastasis. The target ablation zone exceeded the tumor edge (judged by contrast-enhanced US) to avoid marginal residue and recurrence. Ultrasound evaluation was performed at 1 day, 1, 3, 6, 12 and 24 months after treatment, and thyroid function evaluation at the first 6 months. Repeated fine needle aspiration cytology or core needle biopsy pathology was performed at 3 or 6 months after MWA to evaluate residual tumors. Any adverse event associated with MWA was evaluated. Results: The follow-up after MWA lasted 6 (6, 12) months. Tumor volume decreased significantly from 0.06 mm3 (0.04, 0.11 mm3) to 0.03 mm3 (0.00, 0.06 mm3) at 12 months after MWA (P< 0.001), with a median volume reduction ratio of 80.28% (-7.43, 100%) and 16 cases (21.92%) presenting complete remission. The largest diameter, volume and ablation energy were found to be different in patients with and without complete remission 12 months after MWA. On histopathological examinations, no atypical or malignant follicular cells were identified after thermal ablation. The most common pathological characteristics were fibroblastic proliferation (34/39, 87.18%) and chronic inflammation (32/39, 82.05%), followed by infarction (21/39, 53.85%). Five patients were transferred to thyroidectomy and 4 of them were confirmed with local recurrence and/or lymph node metastasis. Serum thyrotropin decreased transiently after MWA (P< 0.01) but normalized thereafter. No serious and permanent complications were reported. Conclusions: MWA is a safe and effective treatment for low-risk PTMC. Fibroblastic proliferation and chronic inflammation are the most common pathological changes after MWA of PTMC.

The role of adjuvant radiation therapy for locoregionally recurrent papillary thyroid carcinoma.

OBJECTIVES: To evaluate the role of adjuvant radiation therapy in patients with locoregionally recurrent (rpT4/N1b) papillary thyroid carcinoma (PTC). METHODS: The medical records of patients with rpT4/N1b PTC who were treated between January 2001 and December 2016 were reviewed. A total of 57 patients were analyzed, of which 24 patients were treated with adjuvant radiation therapy, and 33 patients did not receive adjuvant radiation therapy. Survival outcomes were compared between the 2 treatment groups. The primary endpoint was locoregional recurrence-free survival rate. RESULTS: The median follow-up period for all patients was 10.3 years (range, 2.8-19.2 years). The 15-year locoregional recurrence-free survival rate was 80.5% for those who received adjuvant radiation therapy and 28.1% for those who did not (p<0.001). The 15-year distant metastasis-free survival rate was 48.8% for those who received adjuvant radiation therapy and 33.4% for those who did not (p=0.906). The 15-year overall survival rate was 69.7% for those who received adjuvant radiation therapy and 53.1% for those who did not (p=0.921). CONCLUSIONS: Adjuvant radiation therapy ensured favorable locoregional recurrence-free survival in patients with rT4/N1b PTC and might contribute to improving patients' quality of life by reducing the need for additional salvage surgery and the economic burden of other salvage treatments, such as surgery or radioactive iodine therapy.

Clinical impact of radioactive iodine dose selection based on the number of metastatic lymph nodes in patients with papillary thyroid carcinoma: A multicenter retrospective cohort study.

OBJECTIVE: The aim of this study is to investigate whether the number of metastatic lymph nodes (LNs) could be used as a basis in the radioactive iodine (RAI) dose selection for patients with papillary thyroid carcinoma (PTC). PATIENTS: A total of 595 patients with PTC who received first RAI therapy after total or near-total thyroidectomy and had no evidence of disease in treatment response assessment were retrospectively enroled from five hospitals. The patients were classified into two subgroups based on the number of metastatic LNs (>5). The multivariate Cox-proportional hazard model was performed to identify the significant factors for recurrence prediction in each group as well as all enroled patients. RESULTS: Overall, 22 (3.7%) out of 595 patients had the recurrent disease during the follow-up period. The number of metastatic LNs (>5) was only a significant factor for recurrence prediction in all enroled patients (odds ratio: 7.834, p < .001). In the subgroup with ≤5 metastatic LNs, the presence of extrathyroidal extension was only associated with recurrence (odds ratio: 7.333, p = .024) in multivariate analysis. RAI dose was significantly associated with recurrence rate in which the patients with high-dose RAI (3.7 GBq or higher) had less incidence of recurrence than those with low-dose RAI (1.11 GBq) in the subgroup with more than five metastatic LNs (odds ratio: 6.533, p = .026). CONCLUSIONS: High-dose RAI (≥3.7 GBq) therapy significantly lowered the recurrence rate in patients with more than five metastatic LNs. Therefore, RAI dose should be determined based on the number of metastatic LNs as well as conventional risk factors.

The Value of Pre-Ablative I-131 Scan for Clinical Management in Patients With Differentiated Thyroid Carcinoma.

Background: A diagnostic I-131 (Dx) scan is used to detect a thyroid remnant or metastases before treatment of differentiated thyroid cancer (DTC) with I-131. The aim of this study is to specify in which patients with DTC a Dx scan could have an additional value, by studying the effect of the Dx scan on clinical management. Methods: Patients with DTC, treated with I-131 after thyroidectomy were included in this retrospective cohort study. Twenty-four hours after administration of 37 MBq I-131 a whole body Dx scan and an uptake measurement at the original thyroid bed were performed. Outcomes of the Dx scan and the subsequent changes in clinical management, defined as additional surgery or adjustment of I-131 activity, were reported. Risk factors for a change in clinical management were identified with a binary logistic regression. Results: In 11 (4.2%) patients clinical management was changed, including additional surgery (n=5), lowering I-131 activity (n=5) or both (n=1). Risk factors for a change in clinical management were previous neck surgery (OR 5.9, 95% CI: 1.4-24.5), surgery in a non-tertiary center (OR 13.4, 95% CI: 2.8 - 63.8), TSH <53.4 mU/L (OR 19.64, 95% CI: 4.94-78.13), thyroglobulin ≥50.0 ng/L (OR 7.4, 95% CI: 1.6-34.9) and free T4 ≥4.75 pmol/L (OR 156.8, 95% CI: 128.4-864.2). Conclusion: The Dx scan can potentially change clinical management before treatment with I-131, but the yield is low. A Dx-scan should only be considered for patients with a high pre-scan risk of a change in management, based on patient history and prior center-based surgical outcomes.

Is Postoperative Adjuvant Radioactive Iodine Ablation Therapy Always Necessary for Intermediate-Risk Papillary Thyroid Cancer Patients With Central Neck Metastasis?

BACKGROUND: Papillary thyroid cancer (PTC) is commonly associated with neck lymph node metastasis (LNM), and recurrence does occur after radioactive iodine (RAI) ablation therapy. This study aimed to analyze the effectiveness of RAI ablation with regard to disease recurrence in intermediate-risk PTC patients with neck LNM. In addition, the study identified possible predisposing risk factors that might benefit from RAI ablation and analyzed common RAI therapy complications among these patients. METHODS: A retrospective analysis of 349 intermediate-risk PTC patients with neck LNM who underwent thyroidectomy with neck dissection was performed. The oncologic results and clinicopathologic characteristics of these patients together with the incidence of postoperative RAI therapy complications were evaluated. RESULTS: Of the 349 patients, disease recurrence after treatment occurred for 27 patients (8%) during a mean follow-up period of 58.7 months (range 7-133 months). The recurrence-free survival curve of the patients who received postoperative RAI therapy (n = 208) did not differ significantly from that of the patients who did not receive it (n = 141) (P = 0.567). Nine patients without adjuvant RAI therapy (6%, 9/141) had recurrence. The recurrence rate for the central LNM patients without RAI therapy was only 2% (2/106). Both of these patients with recurrence had pathologic extranodal spread (ENS) and a high number (> 5) of metastatic central LNs. Postoperative RAI-related complications were observed in 24 patients (12%). CONCLUSIONS: Postoperative RAI is not necessary for intermediate-risk papillary thyroid cancer patients with central LNM, especially for patients with negative ENS and low number (< 5) of metastatic lymph nodes.