Re-treatment With Adjuvant Radioactive Iodine Does Not Improve Recurrence-Free Survival of Patients With Differentiated Thyroid Cancer

Second radioiodine treatment in patients with differentiated thyroid carcinoma: Causes and effects

INTRODUCTION

Patients with incomplete response to initial therapy of thyroid cancer can be managed with ongoing observation or potentially additional therapies. Our aim was to assess the effect of a second radioactive iodine treatment (RAIT) and its relationship with causes and clinical variables.

MATERIAL AND METHODS

Patients undergoing a second RAIT for biochemical or structural incomplete response to initial therapy of DTC were retrospectively included (n=120). They were categorised based on the American Thyroid Association (ATA) classification of response to initial therapy. Patients were reclassified in the following 6-18 months after second RAIT based on imaging findings and measurements of thyroglobulin and antithyroglobulin antibody levels. The associations of a downgrading of response category and progression-free survival (PFS), and the related variables, were evaluated.

RESULTS

Sixty-six patients (55%) had a downgrading on ATA response category after second RAIT. A significant interdependence of causes for second RAIT and outcomes was found (χ2=29.400, p=0.001), with patients with neck reoperation showing a higher rate of indeterminate or excellent responses. A significant association between ATA response to second RAIT and absence of structural progression was found (χ2=44.914, p<0.001), with less structural progression in patients with downgrading on ATA response (χ2=30.914, p<0.001). There was also significant interdependence to some clinical variables, such as AJCC stage (χ2=8.460, p=0.015), ATA risk classification (χ2=10.694, p=0.005) and initial N stage (χ2=8.485, p=0.004).

CONCLUSIONS

In selected cases, a second RAIT could lead to more robust responses with a potential improvement in prognosis in patients with incomplete response to initial DTC treatment.

Surgical resection of recurrent differentiated thyroid cancer: patterns, detection, staging, and treatment of 683 patients

Background

Despite improvements in overall survival, the recurrence of differentiated thyroid cancer (DTC) is becoming more common and remains a challenge necessitating accurate reappraisal of the patient. This study aimed to describe the characteristics, reasons, morbidity, and strategies of second operations for DTC.

Methods

This was a retrospective observational study of patients with DTC who underwent a second surgery between June 2008 and June 2021 in the Department of Thyroid Surgery at China-Japanese Union Hospital, Jilin University, P.R. China. All clinical characteristics were recorded, and the analysis was estimated using SPSS.

Results

Second surgeries were detected in 683 patients. The proportion of second operations changed with the update of international guidelines from 2015 (P < 0.001). The true recurrence rate progressively increased from 21.3% to 61.5%. The rate of an "absence of preoperative FNA" or an "absence of intraoperative pathology at first surgery" decreased from 49.8% to 12.7%, while that of a "misdiagnosis of preoperative FNA at second surgery" decreased from 10% to 1.8%. The most common tumor location during the second surgery was the lateral lymph nodes (n = 104, 36.5%), with a median time to relapse of 36 months. Completion of thyroidectomy and lymph node dissection correlated with the second operation.

Conclusion

After 2015, second surgeries were more standardized, the incidence of complications decreased, and real recurrence became the most common reason for a second DTC surgery.

Utility of adjuvant radioactive iodine therapy after reoperation in papillary thyroid carcinoma with cervical lymph node recurrence

PURPOSE

The aim of this study was to evaluate the utility of RAI therapy after reoperation for patients with LN relapse.

MATERIALS AND METHODS

We retrospectively evaluated PTC patients who had undergone reoperation due to cervical LN recurrence. We used the chi-square test, Fisher's exact test, Student's t test and the Mann-Whitney U test to compare characteristics between patients retreated with RAI and those who did not receive RAI after reoperation. A multivariate logistic regression model was used to determine the association between RAI and biochemical response. By means of the Kaplan-Meier estimator and a multivariate Cox proportional hazard model, we assessed whether administration of RAI after reoperation is associated with improved prognosis.

RESULTS

RAI therapy was closely associated with a superior biochemical response in all selected patients according to both univariate (p = 0.012) and multivariate analyses (p = 0.020). Thirteen of 97 patients developed a second recurrence or progression of structural disease during follow-up. A Kaplan-Meier progression-free survival (PFS) curve showed that high post-retreatment thyroglobulin (Tg) levels (≥ 1 ng/mL) were associated with unfavourable prognosis (p = 0.0172). In the subgroup analysis, univariate analysis revealed that only patients without extranodal invasion who received adjuvant RAI therapy achieved better PFS than those who did not receive RAI therapy (p = 0.0203). Multivariate analysis showed that RAI (p = 0.045) also improved PFS in patients without extranodal invasion.

CONCLUSIONS

Adjuvant RAI after reoperation for PTC recurrence/persistence was associated with a favourable biochemical response and tended to increase PFS. Specifically, it was significantly associated with improved PFS only in patients without extranodal extension.

The efficacy of adjuvant radioactive iodine after reoperation in patients with persistent or recurrent differentiated thyroid cancer: a systematic review

OBJECTIVE

The effectiveness of adjuvant radioiodine (RAI) after reoperation in patients with persistent or recurrent differentiated thyroid cancer (DTC) is controversial. Although various organizations recognize that strong evidence for the use of RAI is lacking, they continue to recommend the use of adjuvant RAI therapy for select groups of patients. This is concerning as RAI therapy has potential side effects such as gastrointestinal symptoms, bone marrow suppression, and gonadal damage.

METHODS

Four electronic databases were systematically searched for randomized trials or observational studies that examined the outcomes of adjuvant RAI after reoperation for recurrent DTC, among patients of any age. The baseline characteristics, treatment response, disease progression, and overall survival of these studies were synthesized and reported. A meta-analysis of the use of RAI on progression-free survival was also performed.

RESULTS

Six observational studies, comprising a combined cohort of 437 patients who underwent reoperation, were included from 1212 records. Adjuvant RAI after reoperation in recurrent DTC was not associated with longer progression-free or overall survival. There was also no association of RAI with excellent structural or biochemical treatment response, lower thyroglobulin levels, nor a lower rate of second recurrence or distant metastases.

CONCLUSIONS

Adjuvant RAI after reoperation in recurrent DTC was not associated with improved cancer or treatment-related outcomes. However, as the included studies were of inadequate quality, there is an urgent need for randomized trials and well-analyzed cohort studies. Physicians should exercise clinical judgment to prescribe adjuvant RAI for only selected, high-risk patients.

The outcomes and prognostic factors of patients who underwent reoperation for persistent/recurrent papillary thyroid carcinoma

BACKGROUND

While the most suitable approach for treating persistent/recurrent papillary thyroid carcinoma (PTC) remains controversial, reoperation may be considered an effective method. The efficacy of reoperation in patients with locoregional persistent/recurrent PTC, especially those with unsatisfactory radioactive iodine (RAI) ablation results, is still uncertain. This study aimed to clarify the clinical management strategies for locoregional persistent/recurrent PTC and to explore factors that may affect long-term patient outcomes after reoperation.

METHODS

In total, 124 patients who initially underwent thyroidectomy and variable extents of RAI therapy and finally received reoperation for locoregionally persistent/recurrent PTC were included. The parameters associated with recurrence-free survival (RFS) were analysed using a Cox proportional hazards model.

RESULTS

Overall, 124 patients presented with structural disease after initial therapy and underwent secondary surgical resection, of whom 32 patients developed further structural disease during follow-up after reoperation. At the time of reoperation, metastatic lymph nodes with extranodal extension (P = 0.023) and high unstimulated thyroglobulin (unstim-Tg) levels after reoperation (post-reop) (P = 0.001) were independent prognostic factors for RFS. Neither RAI avidity nor the frequency and dose of RAI therapies before reoperation affected RFS.

CONCLUSIONS

Reoperation is an ideal clinical treatment strategy for structural locoregional persistent/recurrent PTC, and repeated empirical RAI therapies performed prior to reoperation may not contribute to the long-term outcomes of persistent/recurrent PTC patients. Metastatic lymph nodes with extranodal extension and post-reop unstim-Tg > 10.1 ng/mL may predict a poor prognosis.

Second Adjuvant Radioiodine Therapy after Reoperation for Locoregionally Persistent or Recurrent Papillary Thyroid Carcinoma

Introduction Differentiated thyroid carcinoma (DTC) has increased incidence. Intermediate- and high-risk patients have lymph node relapse rate ranging from 10 to 50%, and receive multiple reinterventions, increasing the morbidity of the disease. Currently, there are no established guidelines for the use of second radioactive iodine (RAI) therapy after the reintervention for local recurrence.

Materials and Methods This is a retrospective review of the medical records of 1,299 patients treated from January 2016 to July 2019 with DTC. We included 48 patients who received total thyroidectomy, RAI remnant ablation, surgery to remove the locally recurrent/persistent papillary thyroid carcinoma (PTC), and received a second RAI therapy.

Results There were no significant differences between thyroglobulin (Tg) levels before reoperation (Tg0), Tg levels postoperatively (Tg1), and Tg levels after 6 months of second adjuvant RAI therapy (Tg2). However, we evidenced a 69.79% drop in first Tg levels (Tg0: 24.7 vs. Tg1: 7.56, p=0.851) and 44.4% decrease in second Tg levels (Tg1: 7.56 vs. Tg2: 4.20, p=0.544). Also, 77.1% of the patients did not have another documented recurrence. The median relapse-free time was 10.9 months (range: 1.3–58.2 months).

Conclusion The results of the study cannot assess that a second RAI treatment after reoperation for locoregionally persistent or recurrent disease have a significant impact on treatment outcomes in intermediate- or high-risk patients with PTC. However, the 77.1% of patients have not presented a second documented recurrence and the median values of Tg and TgAb levels showed a substantial decrease after surgery and second RAI treatment.

UPDATED UNDERSTANDING OF THE MOLECULAR TARGETS OF RADIOIODINE IN DIFFERENTIATED THYROID CANCER

Radioactive iodine (RAI) therapy is a mainstay adjuvant treatment for thyroid cancer. Administration of RAI therapy after total or near-total thyroidectomy has shown a survival advantage in numerous properly selected patients. However, the role of RAI therapy after reoperation for persistent or recurrent differentiated thyroid carcinomas (DTCs) is unclear. One reason may be the possible downregulation of the I- transport system after primary surgery. RAI is transported by the sodium iodide symporter (NIS), PENDRIN, anoctamin 1 (ANO1) and cystic fibrosis transmembrane conductance regulator (CFTR) and emits β particles that destroy follicular cells. The identification of pathways of iodide (I-) transport has allowed use of the transport system to render tumours susceptible to RAI treatment via gene therapy. This review focuses on the effect of RAI therapy in follicular cell-derived thyroid cancers and offers potential novel targets that enable improved radioiodine uptake and thus an improved prognosis of thyroid cancer.

Role of adjuvant therapy with radioactive iodine in patients with elevated serum thyroglobulin after neck reoperation due to recurrent papillary thyroid cancer: a monoinstitutional comparative study

BACKGROUND

Most patients with papillary thyroid cancer (PTC) and lymph node metastases (LNM) undergoing reoperation do not show apparent disease after this procedure, but serum thyroglobulin (Tg) continues to be elevated in part of them. This study evaluated adjuvant therapy with ¹³¹I in these patients.

METHODS

Patients with PTC and LNM diagnosed after initial therapy were selected. Patients undergoing reoperation and those without apparent disease after this procedure, but with nonstimulated Tg ≥1 ng/ml 6 months after reoperation, were included. The first 25 patients were submitted to therapy with ¹³¹I (groups A) and the subsequent 30 patients did not receive this therapy (group B).

RESULTS

Groups A and B were similar. During further follow-up, 21 patients developed structural disease and 34 continued without detectable disease (eight achieved complete remission). The outcomes were similar in groups A and B. Patients with Tg reduction >50% after reoperation tended to have a lower risk of recurrence (22.7 versus 48.5%), notably distant metastases (0 versus 15.1%), and were more likely to achieve complete remission (28 versus 3%). Patients with LNM FDG-positive had a higher risk of recurrence (54.5 versus 11.7%) and were less likely to achieve complete remission (3 versus 29.4%) after reoperation.

CONCLUSION

Our results suggest that therapy with ¹³¹I apparently does not prevent recurrences among patients who continue to have elevated Tg after neck reoperation. Further studies involving these patients are necessary, especially those who are at high risk of recurrence.