Selective use of radioactive iodine (RAI) in thyroid cancer: No longer "one size fits all"

Assessing the role of central lymph node ratio in predicting recurrence in N1a low-to-intermediate risk papillary thyroid carcinoma

Introduction

Lymph node metastasis in patients with papillary thyroid carcinoma (PTC) is associated with postoperative recurrence. Recently, most studies have focused on the evaluation of recurrence in patients with late-stage PTC, with limited data on those with early-stage PTC. We aimed to assess the relationship between lymph node ratio (LNR) and recurrence in low-to-intermediate-risk patients and validate its diagnostic efficiency in both structural (STR) and biochemical recurrence (BIR).

Methods

Clinical data of patients with PTC diagnosed at the Affiliated Hospital of Jining Medical University were retrospectively collected. The optimal LNR cut-off values for disease-free survival (DFS) were determined using X-tile software. Predictors were validated using univariate and multivariate Cox regression analyses.

Results

LNR had a higher diagnostic effectiveness than metastatic lymph nodes in patients with low-to-intermediate recurrence risk N1a PTC. The optimal LNR cutoff values for STR and BIR were 0.75 and 0.80, respectively. Multivariate Cox regression analysis showed that LNR≥0.75 and LNR≥0.80 were independent factors for STR and BIR, respectively. The 5-year DFS was 90.5% in the high LNR (≥0.75) and 96.8% in low LNR (<0.75) groups for STR. Regarding BIR, the 5-year DFS was 75.7% in the high LNR (≥0.80) and 86.9% in low LNR (<0.80) groups. The high and low LNR survival curves exhibited significant differences on the log-rank test.

Conclusion

LNR was associated with recurrence in patients with low-to-intermediate recurrence risk N1a PTC. We recommend those with LNR≥0.75 require a comprehensive evaluation of lateral neck lymphadenopathy and consideration for lateral neck dissection and RAI treatment.

Survival benefit of active surveillance for papillary thyroid carcinoma: a propensity score matching analysis based on SEER database

Background

Over-treatment of papillary thyroid microcarcinoma (PTMC) has become a common issue. Although active surveillance (AS) has been proposed as an alternative treatment to immediate surgery for PTMC, its inclusion criteria and mortality risk have not been clearly defined. The purpose of this study was to investigate whether surgery can achieve significant survival benefits in patients with larger tumor diameter of papillary thyroid carcinoma (PTC), in order to evaluate the feasibility of expanding the threshold for active surveillance.

Methods

This study retrospectively collected data of patients with papillary thyroid carcinoma from the Surveillance, Epidemiology, and End Results (SEER) database between 2000 and 2019. The propensity score matching (PSM) method was used to minimize confounding factors and selection bias between the surgery and non-surgery groups, and to compare the clinical and pathological characteristics between the two groups based on the SEER cohort. Meanwhile, the impact of surgery on prognosis was compared using Kaplan-Meier estimates and Cox proportional hazard models.

Results

A total of 175,195 patients were extracted from the database, including 686 patients who received non-surgical treatment, and were matched 1:1 with patients who received surgical treatment using propensity score matching. The Cox proportional hazard forest plot showed that age was the most important factor affecting overall survival (OS) of patients, while tumor size was the most important factor affecting disease-specific survival (DSS) of patients. In terms of tumor size, there was no significant difference in DSS between PTC patients with tumor size of 0-1.0cm who underwent surgical treatment and those who underwent non-surgical treatment, and the relative survival risk began to increase after the tumor size exceeded 2.0cm. Additionally, the Cox proportional hazard forest plot showed that chemotherapy, radioactive iodine, and multifocality were negative factors affecting DSS. Moreover, the risk of death increased over time, and no plateau phase was observed.

Conclusion

For patients with papillary thyroid carcinoma (PTC) staged as T1N0M0, AS is a feasible management strategy. As the tumor diameter increases, the risk of death without surgical treatment gradually increases, but there may be a threshold. Within this range, a non-surgical approach may be a potentially viable management strategy. However, beyond this range, surgery may be more beneficial for patient survival. Therefore, it is necessary to conduct more large-scale prospective randomized controlled trials to further confirm these findings.

I-PET score: Combining whole body iodine and 18 F-FDG PET/CT imaging to predict progression in structurally or biochemically incomplete thyroid cancer

OBJECTIVE

We propose a new scoring system (I-PET) combining whole body scan (WBS) and FDG findings to identify patients who have or are likely to become refractory to radioactive iodine.

DESIGN

Retrospective analysis of 142 patients age >18 with differentiated thyroid cancer who had a F-18 labelled fluoro-2-deoxyglucose (¹⁸ F-FDG) positron emission tomography (PET) and WBS within a 6-month period between 2010 and 2020. Pairs of ¹⁸ F-FDG PET and WBS were reviewed by three independent nuclear medicine physicians and an I-PET score was assigned: I-PET [0]: Iodine -ve/FDG -ve, I-PET [1]: Iodine +ve/FDG -ve, I-PET [2]: Iodine +ve/FDG +ve and I-PET [3]: Iodine -ve/FDG +ve. Patients with FDG +ve lesions (I-PET [2] and I-PET [3]) were further classified into groups A and B if SUVmax was ≤5 or >5, respectively. Follow-up data were obtained by chart review. Progression was defined as structural progression as per RECIST 1.1 or further surgical intervention; or biochemical progression as unstimulated thyroglobulin increasing >20% from baseline.

RESULTS

Of 142 patients included in the study 121 patients had follow-up data available for review. At baseline, 49 patients were classified as I-PET [0], 10 as I-PET [1], 16 as I-PET [2] and 46 as I-PET [3]. Progression was seen in 11/49 (22%) of I-PET [0], 4/10 (40%) of I-PET [1], 10/16 (63%) of I-PET [2] and 34/46 (74%) of I-PET [3] (p < 0.001). I-PET [2B] and I-PET [3B] had a progression rate of 88% (7/8) and 78% (25/32), respectively. I-PET [3B] were 9.6 times more likely to commence multikinase inhibitor therapy (p = 0.001) and had 8 times greater mortality (p = 0.003) than patients in other I-PET groups combined.

CONCLUSION

I-PET is a simple readily acquired imaging biomarker that potentially enhances the dynamic risk stratification and guide treatment in thyroid cancer.

Radioactive Iodine Therapy Does not Improve Cancer-specific Survival in Hürthle Cell Carcinoma of the Thyroid

CONTEXT

It is unclear whether radioactive iodine (RAI) therapy could improve cancer-specific survival (CSS) in patients with Hürthle cell carcinoma (HCC) of the thyroid.

OBJECTIVE

To investigate the effect of RAI on CSS in HCC patients.

METHODS

HCC patients who underwent total thyroidectomy (TT) were identified from the Surveillance, Epidemiology, and End Results (SEER) database between 2000 and 2018. The Kaplan-Meier method and the Cox proportional hazards regression model were used to evaluate CSS. Propensity score-matched (PSM) analyses were performed to control the influence of potential confounders.

RESULTS

A total of 2279 patients were identified. RAI treatment was not significantly associated with improved CSS in overall or PSM cohort. Subgroup analyses indicated similar results, even in patients with aggressive features such as age 55 years or older, tumor size greater than 40 mm, distant disease in SEER staging, extrathyroidal extension, and lymph node metastases (all P > .05).

CONCLUSION

RAI has no statistically significant influence on the CSS in HCC patients. This information may aid in decision-making for RAI therapy in these patients.

Thyroglobulin-Based Risk Factor Repositioning for Determining Radioactive Iodine Activity in Patients with Papillary Thyroid Carcinoma: a Multicenter Retrospective Cohort Study

Purpose

We aimed to investigate the impact of various factors including radioactive iodine (RAI) activity on the therapeutic response according to the range of serum thyroglobulin (Tg) in patients with papillary thyroid carcinoma (PTC).

Methods

A total of 2809 patients were retrospectively enrolled from 24 hospitals. They were divided into four subgroups according to their serum Tg (stimulated Tg, sTg) or anti-Tg antibody (TgAb) levels, measured just before RAI therapy: sTg < 2 ng/mL, 2 ≤ sTg < 10 ng/mL, sTg ≥ 10 ng/mL, and TgAb > 100 IU/mL. The clinicopathologic factors for therapeutic responses, which were classified as acceptable response (AR) or non-AR, were compared in each subgroup.

Results

Clinical impact of the pN category on therapeutic response was different among subgroups based on sTg levels (subgroups with sTg < 2 ng/mL (P = 0.057), 2 ≤ sTg < 10 ng/mL (P = 0.032), and sTg ≥ 10 ng/mL (P = 0.001)). The pN category was also a significant factor in the subgroup with TgAb > 100 IU/mL (P = 0.006). The pT category was not associated with therapeutic response regardless of the sTg level. High activities of RAI (≥ 3.70 GBq) were associated with favorable therapeutic responses in only the subgroup with sTg ≥ 10 ng/mL (P = 0.044).

Conclusion

Risk factors for response prediction could be repositioned based on the serum Tg before RAI therapy. RAI activity should be determined while considering the serum Tg-aided remnant thyroid or malignant tissues as well as conventional factors.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13139-022-00756-4.

Radioactive iodine therapy: multiple faces of the same polyhedron

The incidence of differentiated thyroid carcinoma (DTC) has increased in recent decades with early stage, low risk papillary thyroid cancer (PTC) being detected and diagnosed. As a result, the psychological, financial, and clinical ramifications of overdiagnosis and excessively aggressive therapy are being increasingly recognized with many authorities calling for a re-evaluation of the traditional "one size fits all" management approaches. To address these critical issues, most thyroid cancer guidelines endorse a more risk adapted management strategy where the intensity of therapy and follow up is matched to the anticipated risk of recurrence and death from DTC for each patient. This "less is more" strategy provides for a minimalistic management approach for properly selected patients with low-risk DTC. This has re-kindled the long-standing debate regarding the routine use of radioactive iodine therapy (RIT) in DTC. Although recent guidelines have moved toward a more selective use of RIT, particular in patients with low-intermediate risk DTC, the proper selection of patients, the expected benefit, and the potential risks continue to be a source of ongoing controversy and debate. In this manuscript, we will review the wide range of clinical, imaging, medical team, and patient factors that must be considered when evaluating individual patients for RIT. Through a review of the current literature evaluating the potential benefits and risks of RIT, we will present a risk adapted approach to proper patient selection for RIT which emphasizes peri-operative risk stratification as the primary tool that clinicians should use to guide initial RIT management recommendations.

Perception of risk and treatment decisions in the management of differentiated thyroid cancer

BACKGROUND AND OBJECTIVES

The recent de-escalation of care for differentiated thyroid cancer (DTC) has broadened the range of initial treatment options. We examined the association between physicians' perception of risk and their management of DTC.

METHODS

Thyroid specialists were surveyed with four clinical vignettes: (1) indeterminate nodule (2) tall cell variant papillary thyroid cancer (PTC), (3) papillary thyroid microcarcinoma (mPTC), and (4) classic PTC. Participants judged the operative risks and likelihood of structural cancer recurrence associated with more versus less aggressive treatments. A logistic mixed effect model was used to predict treatment choice.

RESULTS

Among 183 respondents (13.4% response rate), 44% were surgical and 56% medical thyroid specialists. Risk estimates and treatment recommendation varied markedly in each case. Respondents' estimated risk of 10-year cancer recurrence after lobectomy for a 2.0-cm PTC ranged from 1% to 53% (interquartile range [IQR]: 3%-12%), with 66% recommending lobectomy and 34% total thyroidectomy. Respondents' estimated 5-year risk of metastastic disease during active surveillance of an 0.8-cm mPTC ranged from 0% to 95% (IQR: 4%-15%), with 36% choosing active surveillance. Overall, differences in perceived risk reduction explained 10.3% of the observed variance in decision-making.

CONCLUSIONS

Most of the variation in thyroid cancer treatment aggressiveness is unrelated to perceived risk of cancer recurrence.

Surgery and Radioactive Iodine Therapeutic Strategy for Patients Greater Than 60 Years of Age with Differentiated Thyroid Cancer

PURPOSE

The purpose of the current study was to determine whether older patients with differentiated thyroid cancer (DTC) who received surgical treatment had a better cause-specific survival (CSS) than patients who were recommended surgery, but declined, and whether patients who underwent postoperative RAI-131 therapy had an impact on CSS based on TNM staging and number of lymph node metastases for all total or near-total thyroidectomy patients. Patients and Methods: This retrospective, population-based study analyzed the clinical data of 162 DTC patients from signal institution in China and 26,487 cases from the Surveillance, Epidemiology, and End Results (SEER) program registry. The patients were divided into two groups (underwent surgery and surgery recommended, but not performed) in the SEER cohort. Furthermore, patients were grouped as follows: T4; N1b; M1; T1-3N0-1a; specific number of lymph node metastases; and total or near-total thyroidectomy. Results: The 120-month cause-specific survival (CSS) rate of women and men showed a gradual declining trend from 60-64 to ≥80 years of age in the group that underwent surgery. The CSS rate of women and men showed a marked downward and irregular trend with an increase in age in the recommended, but no surgery group in the SEER cohort. Univariate analysis indicated that the surgery group had a higher 120-month CSS in women in most stages and men, compared with the no surgery group in the SEER cohort. The analysis of the SEER cohort showed that RAI-131 therapy was associated with an improved 80-month CSS in T4/N1b/M1 women (P < 0.0183) and men (P < 0.0011). However, there were no CSS differences between the RAI-131 therapy and the no-RAI-131 group for the patients with T4/N1b/M1 (AJCC 7th) thyroid cancer in the Chinese cohort. There was no CSS difference in women or men between the T1-3N0 and T1-3N1a patients in the SEER cohort. And similar findings were observed in T1-3N1a patients in the Chinese cohort. There was no statistical difference between the two subgroups. Conclusions: Surgical treatment should be recommended for elderly DTC patients because surgery can lead to a better CSS. High-risk patients achieve a higher benefit-to-risk ratio with RAI-131 therapy. To avoid the adverse effects associated with RAI-131 therapy, a multidisciplinary discussion should be arranged for intermediate- and low-risk patients.

Inability of Radioiodine Remnant Ablation to Improve Postoperative Outcome in Adult Patients with Low-Risk Papillary Thyroid Carcinoma

OBJECTIVE

To determine whether radioiodine remnant ablation (RRA) reduces cause-specific mortality (CSM) or tumor recurrence (TR) rate after bilateral lobar resection (BLR).

PATIENTS AND METHODS

There were 2952 low-risk adult papillary thyroid cancer (LRAPTC) patients (with MACIS scores <6) who underwent potentially curative BLR during 1955-2014. During 1955-1974, 1975-1994, and 1995-2014, RRA was administered in 3%, 49%, and 28%. Statistical analyses were performed using SAS software.

RESULTS

During 1955-1974, the 20-year CSM and TR rates after BLR alone were 1.0% and 6.8%; rates after BLR+RRA were 0% (P=.63) and 5.9% (P=.82). During 1975-1994, post-BLR 20-year rates for CSM and TR were 0.3% and 7.5%; after BLR+RRA, rates were higher at 0.9% (P=.31) and 12.8% (P=.01). When TR rates were examined separately for 448 node-negative and 317 node-positive patients, differences were nonsignificant. In 1995-2014, post-BLR 20-year CSM and TR rates were 0% and 9.2%; rates after BLR+RRA were higher at 1.4% (P=.19) and 21.0% (P<.001). In 890 pN0 cases, 15-year locoregional recurrence rates were 3.4% after BLR and 3.7% after BLR+RRA (P=.99). In 740 pN1 patients, 15-year locoregional recurrence rates were 10% higher after BLR+RRA compared with BLR alone (P=.01). However, this difference became nonsignificant when stratified by numbers of metastatic nodes.

CONCLUSION

RRA administered to LRAPTC patients during 1955-2014 did not reduce either the CSM or TR rate. We would therefore not recommend RRA in LRAPTC patients undergoing BLR with curative intent.

Impacts of the American Joint Committee on Cancer (AJCC) 8th edition tumor, node, metastasis (TNM) staging system on outcomes of differentiated thyroid cancer in Thai patients

Background

In 2018, the American Joint Committee on Cancer (AJCC) 8^th edition (AJCC8) was introduced to replace the previous version (AJCC7) due to superiority of AJCC8 over AJCC7 for better prediction of survival from thyroid cancer.

Aim

To compare AJCC staging systems with the American Thyroid Association (ATA) risk classification for the prediction of 5-year disease-free survival (DFS), and 5-year disease-specific survival (DSS) in Thai patients.

Methods

We retrospectively reviewed all patients with histopathologic diagnosis of DTC who were treated at Theptarin Hospital, Bangkok, Thailand from 1987 to 2019.

Results

The study cohort included 262 differentiated thyroid cancer (DTC) patients (papillary thyroid cancer 89.7% with a median time of follow-up 7.8 years). The number (%) of patients within each stage group by AJCC7 and AJCC8 respectively are as follows: Stage I: 173 (66.0%) vs. 232 (88.5%), Stage II: 33 (12.6%) vs. 24 (9.2%), Stage III: 36 (13.7%) vs. 2 (0.8%), Stage IV: 20 (7.7%) vs. 4 (1.5%). The ATA high risk group was found in 24.3% of AJCC7 Stage I compared with 23.7% of AJCC8 Stage I. The 5-year DFS rates in patients classified as stages I, II, III, and IV by AJCC8 were 87.9%, 45.8%, 0% and 25%, respectively. The 5-year DSS rates in patients classified as stages I, II, III and IV by AJCC8 were 98.7%, 100%, 100% and 0%, respectively. AJCC8 was more predictive of DFS rate than AJCC7.

Conclusions

Our study is in accord with previous studies that AJCC8 downstage a significant percentage of patients with DTC and correlated with better prognostic validity. However, even a person at low risk for mortality can be at high risk for recurrence.

18F-FDG-PET/CT in Patients with Advanced, Radioiodine Refractory Thyroid Cancer Treated with Lenvatinib

Simple Summary

In patients with advanced radioiodine refractory differentiated thyroid carcinoma (DTC), therapeutic options are limited. In the “Study of (E7080) Lenvatinib in Differentiated Cancer of the Thyroid (SELECT)”, Lenvatinib significantly prolonged the progression-free survival, resulting in a more frequent use in clinical practice for this patient group. Due to considerable side effects, an accurate assessment of response to treatment is crucial in these patients. Therefore, we aimed to improve treatment individualization and reduce unnecessary therapies by selecting patients who will most likely benefit from Lenvatinib treatment using 2-deoxy-2-[¹⁸F] fluoro-D-glucose positron-emission-tomography/computed-tomography.

Abstract

Background: The tyrosine kinase inhibitor (TKI) Lenvatinib represents one of the most effective therapeutic options in patients with advanced radioiodine refractory differentiated thyroid carcinoma (DTC). We aimed to assess the role of 2-deoxy-2-[¹⁸F] fluoro-D-glucose positron-emission-tomography/computed-tomography (¹⁸F-FDG-PET/CT) in the monitoring of functional tumor response compared to morphological response. Methods: In 22 patients, a modified Positron Emission Tomography Response Criteria In Solid Tumors (mPERCIST) evaluation before treatment with Lenvatinib and at 3 and 6 month follow up was performed. Further PET-parameters and morphologic tumor response using Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 were assessed and their prediction of progression-free survival (PFS) and disease-specific survival (DSS) was evaluated. Results: Most patients were rated stable in morphological evaluation and progressive using a metabolic response. All patients who responded to therapy through RECIST showed a decline in nearly all Positron Emission Tomography (PET)-parameters. For both time-points, non-responders according to mPERCIST showed significantly lower median PFS and DSS, whereas according to RECIST, only DSS was significantly lower. Conclusion: Tumor response assessment by ¹⁸F-FDG-PET outperforms morphological response assessment by CT in patients with advanced radioiodine refractory DTC treated with Lenvatinib, which seems to be correlated with clinical outcomes.

Clinical Outcomes after Early and Delayed Radioiodine Remnant Ablation in Patients with Low-Risk Papillary Thyroid Carcinoma: Propensity Score Matching Analysis

BACKGROUND

The clinical outcomes of delayed radioiodine remnant ablation (RRA) therapy in patients with low-risk papillary thyroid carcinoma (PTC) are unclear. We aimed to evaluate the clinical impact of the interval between total thyroidectomy (TT) and RRA therapy in patients with low-risk PTC.

METHODS

We included 526 patients who underwent TT and RRA for low-risk PTC with a primary tumor size of >1 cm between 2000 and 2012. Patients were divided into the early (<90 days) and the delayed (≥90 days) RRA groups based on the interval between TT and RRA. The results of diagnostic whole-body scan (DxWBS), ongoing risk stratification (ORS; response to therapy), and disease-free survival (DFS) were evaluated before and after propensity score matching (PSM).

RESULTS

Among the 526 patients, 75 (14.3%) patients underwent delayed RRA; they had more cervical lymph node metastasis and received a higher RRA dose than those who underwent early RRA. The median follow-up period was 9.1 years after initial therapy, and the structural recurrence rate was 1.9%. In DxWBS, 60 patients had focal iodine uptake limited in operative bed, with no significant difference between groups. According to ORS, 78%, 20%, 1%, and 1% patients were classified into excellent, indeterminate, biochemical incomplete, and structural incomplete response groups, respectively. There was no significant difference in ORS or DFS between groups before and after PSM.

CONCLUSION

The timing of the first RRA had no clinical impact in patients with low-risk PTC. Thus, the clinical decision for RRA can be determined >3 months after TT considering other prognostic factors.

The impact of radioactive iodine treatment on survival among papillary thyroid cancer patients according to the 7th and 8th editions of the AJCC/TNM staging system: a SEER-based study

Papillary thyroid cancer is a very common endocrine malignancy. The 8th American Joint Committee on Cancer/Union for International Cancer Control (AJCC/UICC) staging system introduced major changes. We conducted this retrospective cohort analysis to assess the benefits of radioactive iodine (RAI) according to different stratification of patients. The source of the data was the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database. From 2006 to 2015, patients with papillary thyroid cancer were included in our study. The interactions between different variables and RAI treatment were tested by multivariate Cox regression models to compare the survival differences according to RAI treatment between the patients assessed with the 7th and 8th edition of the AJCC/TNM staging system. The results of the interaction analysis and group comparisons indicated that the effects of RAI treatment on patients staged with the 7th and 8th editions were similar. Patients with early Stage, early T stage, N0 and subtotal or near total thyroidectomy benefited greatly from RAI treatment. Patients with Stage III according to the 8th edition benefited less from RAI than patients with Stage III according to the 7th edition. Patients with T1a benefited from RAI but benefited less than patients with other T stages. Patients with T3a benefited more from RAI than those with T3b. According to the 8th edition, Stage III/IV more accurately differentiates patients with advanced stage disease. These patients benefitted less from RAI treatment, which may be due to the relatively weaker iodine uptake by tumor cells. T1a patients benefitted less than patients with other T stages. The difference in RAI benefit between patients with T3a and T3b is a novel finding in our study.

The Identification of Intraoperative Risk Factors Can Reduce, but Not Exclude, the Need for Completion Thyroidectomy in Low-Risk Papillary Thyroid Cancer Patients

Background: The extent of initial surgical resection for low-risk papillary thyroid cancer (PTC) remains debatable. Since the 2015 American Thyroid Association (ATA) guidelines, several retrospective studies have reported that 40-60% of patients initially treated with lobectomy would require a completion thyroidectomy (CTx) due to high-risk pathological features (HRFs). These studies are limited by variable preoperative stratification and inability to quantify the value of intraoperative assessment. The study objectives were to determine whether diligent preoperative and intraoperative assessment improves the appropriateness of initial surgery for low-risk PTCs and whether varying the criteria for lobectomy reduces the need for CTx. Methods: A prospectively collected province-wide database was analyzed over a 10-year period (2008-2017) for patients who underwent a total thyroidectomy (TT) for PTC without preoperative HRFs. All patients had preoperative ultrasound and fine-needle aspirates. Unique to this database are mandatory synoptic operative fields that identify intraoperative risk factors such as positive lymph nodes and local invasion. Results: In total, 74% of patients (709/959) were deemed eligible for lobectomy. Of those eligible, 149 (21%) had intraoperative risk factors that would necessitate conversion to TT at the initial operation. A further 209 (30%) would require CTx due to HRFs on final pathology. Varying the preoperative criteria for lobectomy did not significantly affect intraoperative conversion or CTx rates. Conclusions: Although intraoperative assessment reduced the need for CTx in 21%, up to 30% of patients would still require a second operation. Altering the preoperative criteria does not influence this outcome. Patients deemed eligible for lobectomy should be informed that despite careful pre- and intraoperative assessment, there is up to a 30% risk of requiring CTx.

Low-dose radioiodine therapy for patients with intermediate- to high-risk differentiated thyroid cancer

OBJECTIVE

The efficacy of low-dose radioiodine therapy (RIT) for intermediate-risk or high-risk differentiated thyroid cancer (DTC) patients is controversial. Because of the country's shortage of medical facilities for RIT, 1110-MBq RIT for higher risk DTC patients has been performed on an outpatient basis since 2010 in Japan. Herein, we addressed this issue and attempted to determine prognostic factors for the prediction of RIT outcomes.

METHODS

We retrospectively analyzed the cases of 119 patients with papillary thyroid cancer who underwent their first RIT with 1110 MBq radioactive iodine (RAI) following a total thyroidectomy, including 65 (54.6%) intermediate-risk and 54 (45.4%) high-risk patients (according to Japan's 2018 clinical practical guidelines for thyroid tumors). Successful ablation was defined when a negative I-131 whole-body scan and thyroglobulin (Tg) < 2 ng/mL were obtained at a diagnostic scan performed 148-560 days (median 261 days) after the first RIT.

RESULTS

The overall ablation success rate was 23.4%. Although the ablation success rates of each pretreatment protocol [recombinant human thyroid stimulating hormone and thyroid hormone withdrawal (THW)] did not differ significantly, THW tended to result in a higher success rate than rhTSH. The Tg level at RIT was the only independent powerful predictive factor for successful ablation. The best cut-off value of Tg for predicting unsuccessful ablation was 9 ng/mL.

CONCLUSIONS

The ablation success rate was much lower than those of earlier studies; the most plausible reason would be that higher risk DTC patients were included in this study. The low-dose RIT routinely performed in Japan might be inadequate for the achievement of successful ablation. At least for patients with Tg > 9 ng/mL at the first RIT, a higher dose of RAI is recommended.

Radioactive iodine ablation post differentiated thyroid cancer surgery: an analysis of use and impact of the American Thyroid Association guidelines

BACKGROUND

The 2009 American Thyroid Association (ATA) three-tiered risk stratification, and its updated version in 2015, provided clearer guidance on the use of radioactive iodine (RAI) ablation in differentiated thyroid cancer (DTC) patients. This study examines the impact of these guidelines on RAI use in our institution.

METHODS

Patients diagnosed with DTC during three different time periods (group 1: 2002-2006, group 2: 2010-2014 and group 3: 2017-2018) were identified and risk stratified according to the ATA guidelines. RAI use and extent of surgery were compared between the three groups. Categorical variables were analysed using Fisher's exact (2 × 2) and chi-squared (>2 × 2) tests.

RESULTS

A total of 415 patients were included (group 1 = 88, group 2 = 215, group 3 = 112). The proportion of patients having total thyroidectomy were 84.6, 84.7 and 69.6% in groups 1, 2 and 3, respectively (P = 0.003). Central lymph node dissection was significantly higher in the more contemporary groups compared to group 1 (9.1 versus 41.9 versus 64.3%, P < 0.001). Overall, fewer patients received RAI in more recent times (76.6 versus 54.8 versus 26.8%, P < 0.001), most evident in the low-risk patients (70 versus 29.1 versus 5.1%, P < 0.001). In the high risk group, the majority received RAI, with no difference between the groups.

CONCLUSION

Comparing DTC patients treated in our unit before and after publications of the 2009 and 2015 ATA guidelines, more nodal surgery was performed with less RAI administered in the latter groups. Better risk stratification according to the ATA guidelines has allowed more judicious use of RAI ablation.

Mortality Risk of Nonoperative Papillary Thyroid Carcinoma: A Corollary for Active Surveillance

Background: Active surveillance is established as an alternative to surgery for papillary thyroid microcarcinomas, but inclusion criteria and mortality risk for pursuing a nonsurgical approach have not been clearly defined. To gauge the feasibility of expanding active surveillance thresholds, we investigated the effects of increasing size and age on disease-specific survival (DSS) in a large nonoperative thyroid cancer cohort, compared against a matched group of surgical patients. Methods: Papillary thyroid carcinoma patients staged T1-4N0M0 were identified in the Surveillance, Epidemiology, and End Results (SEER) database between 1975 and 2015, stratified by nonsurgical and surgical management. Propensity score matching was performed to adjust for imbalances in covariates. Multivariable models were constructed using restricted cubic splines to model nonlinear relationships of age and tumor size with DSS. Results: Overall, 1453 nonoperative patients and 54,718 surgical patients met the inclusion criteria. Collectively, increasing age and size after certain thresholds independently led to greater differences in DSS between nonsurgical and surgical patients. For younger ages (14-55 years), surgical approach compared with nonsurgical approach was not associated with any difference in the 10-year DSS among 0-4 cm cancers (99.8% vs. 100%, p = 0.470), 4.1-6 cm cancers (98.8% vs. 100%, p = 0.599), or >6 cm cancers (97.3% vs. 100%, p = 0.718). Older patients with larger tumors (>75 years, >6 cm) demonstrated the greatest difference in DSS (48.1% vs. 91.3%, p < 0.001). Similar results were found when applying propensity score matching. For age, restricted cubic spline plots showed minimal relative survival hazard in nonoperative cases beginning after age 60 years, with a change point illustrating acceleration in relative hazard beyond age 72 years. For size, relative survival hazard was observed after 2.0 cm and increased slowly with nodule growth up to an inflection point of 4.5 cm. Beyond this, mortality risk escalated with each additional year without plateau. Conclusions: Increasing age and size lead to progressively greater mortality risk without surgery, but only beyond certain thresholds. We define escalating gradients at which a nonsurgical approach may be deemed appropriate, and beyond which survival benefits from surgery become apparent. Such findings reconcile controversial observations regarding age and size in active surveillance and further reshape evolving treatment paradigms in thyroid cancer.

New horizons in radiotherapy for older people

Radiotherapy is an effective, albeit underutilised, treatment for cancer in older adults, especially for those who are surgically inoperable or for whom chemotherapy poses too great a risk. It is estimated that approximately half of patients with cancer could benefit from radiotherapeutic management. This article synthesises the basics of how radiotherapy works, recent developments in the field and considers how this treatment modality may be adapted in an older patient population or may evolve in the future. Technological advances of relevance include Intensity Modulated Radiotherapy (IMRT), Volumetric Modulated Arc therapy (VMAT), Stereotactic Ablative Body Radiotherapy (SABR), proton therapy, MR guided radiotherapy, as well as better image guidance during irradiation in order to improve precision and accuracy. New approaches for better integration of geriatric medicine principles into the oncologic assessment and workup will also be considered, in order to provide more age attuned care. For more informed decision making, a baseline assessment of older radiotherapy patients should encompass some form of Comprehensive Geriatric Assessment. This can facilitate the optimal radiotherapy regime to be selected, to avoid overly toxic regimes in patients with frailty. The review discusses how these new initiatives and technologies have potential for effective oncologic management and can help to reduce the toxicity of treatment for older adults. It concludes by highlighting the need for more evidence in this patient population including better patient selection and support for treatment to enhance person-centred care.

A Case of Papillary Thyroid Carcinoma and Kostmann Syndrome: A Genomic Theranostic Approach for Comprehensive Treatment

BACKGROUND Theranostics is a combined diagnostic and treatment approach to individualized patient care. Kostmann syndrome, or severe congenital neutropenia, is an autosomal recessive disease that affects the production of neutrophils. Papillary thyroid carcinoma (PTC) is the most common type of thyroid malignancy associated with gene alterations, including in the mitogen-activated protein kinase (MAPK) signaling pathway gene. Translocation of the ETS variant 6/neurotrophic receptor tyrosine kinase 3 (ETV6/NTRK3) gene has been implicated in radiation-induced and pediatric forms of thyroid carcinoma but has rarely been described in sporadic PTC. This report is of a case of PTC in a patient with Kostmann syndrome associated with ETV6/NTRK3 gene translocation. CASE REPORT A 32-year-old woman with a history of Kostmann syndrome, acute myeloid leukemia (AML), and chronic graft versus host disease (GVHD) was diagnosed with PTC with cervical lymph node metastases and soft tissue invasion following total thyroidectomy and bilateral modified radical neck dissection. Her postoperative radioactive iodine (RAI) scan confirmed lymph node metastasis. Gene expression studies identified increased expression of iodine-handling genes and ETV6/NTRK3 gene fusion. Because of the bone marrow compromise due to Kostmann syndrome and AML, a careful genomic and molecular analysis was performed to guide therapy. CONCLUSIONS This is the first reported case of the association between PTC, Kostmann syndrome, and ETV6/NTRK3 gene translocation in which multimodality treatment planning was optimized by genomic profiling.

Prognostic Impact of Direct 131I Therapy After Detection of Biochemical Recurrence in Intermediate or High-Risk Differentiated Thyroid Cancer: A Retrospective Cohort Study

Background: Patients treated for intermediate- or high-risk differentiated thyroid carcinoma (DTC) and Thyroglobulin (TG) elevation during follow-up, require a diagnostic whole-body scan (DWBS) and if positive, ¹³¹I treatment. This approach can lead to a delay in treatment and increased costs. The purpose of this study is to compare the oncologic outcomes associated to administration of direct therapy with ¹³¹I at first biochemical recurrence. Methods: Retrospective cohort study of patients with intermediate- or high-risk DTC treated with total thyroidectomy, ¹³¹I ablation and who developed TG elevation during follow-up, between January 2007 and December 2015. Cohort A included patients who underwent a DWBS with 5 mCi of ¹³¹I, and if negative an MRI and/or ¹⁸FDG PET-CT prior to the therapeutic dosage, and cohort B included those who only received a therapeutic dosage of ¹³¹I, without a DWBS or extensive image studies. Main outcomes were second recurrence (SR) and disease-free survival (DFS). The diagnostic accuracy of DWBS was analyzed. Results: Cohorts A and B had 74 and 41 patients, each. By multivariate analysis, age, differentiation grade, TN classification, ablation dose, and performed DWBS (odds ratio 55.1; 95% CI 11.3-269) were associated with SR (p < 0.0001); age, male gender, ablation dose and performed DWBS (hazard ratio 7.79; 95% CI 3.67-16.5) were independent factors associated with DFS (p < 0.0001). DWBS diagnostic accuracy was 36.48%. Conclusion: ¹³¹I treatment in patients with DTC biochemical recurrence and no DWBS or extensive image studies is associated with a significantly lower frequency of SR and an increased DFS. The diagnostic accuracy of DWBS is low, and its clinical efficiency should be defined in prospective phase III studies.

30mCi radioactive iodine achieving comparative excellent response in intermediate/high-risk nonmetastatic papillary thyroid cancer: a propensity score matching study

OBJECTIVE

To determine the efficacy of low-dose radioactive iodine (RAI) therapy (30 mCi, 1110 MBq) in Chinese patients with intermediate- to high-risk papillary thyroid cancer (PTC) without distant metastasis.

DESIGN AND METHODS

This large retrospective study included Chinese patients with PTC that tested negative for thyroglobulin antibodies. Patients were categorized into low-dose (30 mCi, 1110 MBq) and high-dose (>100 mCi, 3700 MBq) RAI groups. Ablation rate and long-term response were compared between groups using propensity score matching (PSM) to minimize bias and confounding.

RESULTS

In total, we included 446 patients. No significant difference in ablation success rate was found between groups (P = 0.305) before or after PSM (N = 162; P = 0.200). Excellent response (ER) rate was not significant between groups before (P = 0.917) or after PSM (P = 0.798). Efficacy of low-dose RAI was similar to that of high-dose RAI in N0- (P = 1.000), N1a- (P = 0.981), and N1b-stage (P = 0.903) patients. Low- and high-dose RAI groups achieved similar ER rates in pre-ablative stimulated thyroglobulin level (≤1 ng/mL, P = 1.000; 1 < ps-Tg ≤ 5 ng/mL, P = 0.444; 5 < ps-Tg ≤ 10 ng/mL, P = 0.665; >10 ng/mL, P = 1.000) and BRAF^V600E-positive (P = 0.324) subgroups.

CONCLUSIONS

Efficacy of low-dose RAI therapy was similar to that of high-dose for ablation and achieving ER in Chinese nonmetastatic intermediate- to high-risk PTC patients. High-dose RAI could not rectify ablation failure or non-ER rates in PTC patients with BRAF^V600E, lymph node metastases, or unfavorable thyroglobulin levels.

Current controversies and future directions in the diagnosis and management of differentiated thyroid cancers

Despite the development of novel diagnostic, surgical, and chemotherapeutic approaches to differentiated thyroid cancers (DTCs), the diagnosis and management of these tumors remains controversial. The most recent American Thyroid Association (ATA) guidelines, released in 2015, reflect a recent shift towards less aggressive management for patients with DTCs. However, many clinicians have expressed concern that more conservative management will put patients at risk for disease recurrence and metastasis. In particular, the management of indeterminate nodules on fine needle aspiration (with special attention to genetic and epigenetic markers of malignancy), the extent of surgery for known differentiated cancers, the role of adjuvant radioactive iodine (RAI) therapy, and novel targeted treatments with tyrosine kinase inhibitors (TKIs) represent current areas of uncertainty and opportunities for future research. In this review, we examine the current state of the art in these areas, and address some of the questions that remain.