Avidity and Outcomes of Radioiodine Therapy for Distant Metastasis of Distinct Types of Differentiated Thyroid Cancer

Clinical and molecular characterisation of metastatic papillary thyroid cancer according to radioiodine therapy outcomes

PURPOSE

Radioiodine (RAI) therapy remains the gold-standard approach for distant metastatic differentiated thyroid cancer (TC). The main objective of our work was to identify the clinical and molecular markers that may help to predict RAI avidity and RAI therapy response of metastatic lesions in a cohort of papillary thyroid cancer (PTC) patients.

METHODS

We performed a retrospective analysis of 122 PTC patients submitted to RAI therapy due to distant metastatic disease. We also analysed, through next-generation sequencing, a custom panel of 78 genes and rearrangements, in a smaller cohort of 31 metastatic PTC, with complete follow-up, available RAI therapy data, and existing tumour sample at our centre.

RESULTS

The most frequent outcome after RAI therapy was progression of disease in 59.0% of cases (n = 71), with median estimate progression-free survival of 30 months. RAI avidity was associated with PTC subtype, age and stimulated thyroglobulin at first RAI therapy for metastatic disease. The most frequently altered genes in the cohort of 31 PTC patients' primary tumours were RAS isoforms (54.8%) and TERT promoter (TERTp) (51.6%). The presence of BRAF p.V600E or RET/PTC alterations was associated with lower avidity (p = 0.012). TERTp mutations were not associated with avidity (p = 1.000) but portended a tendency for a higher rate of progression (p = 0.063); similar results were obtained when RAS and TERTp mutations coexisted (p = 1.000 and p = 0.073, respectively).

CONCLUSIONS

Early identification of molecular markers in primary tumours may help to predict RAI therapy avidity, the response of metastatic lesions and to select the patients that may benefit the most from other systemic therapies.

Comparison of Treatment and Prognosis Between Follicular Variant Papillary Thyroid Carcinoma and Classical Papillary Thyroid Carcinoma

This cohort study evaluated the associations of different treatments with the prognosis of follicular variant papillary thyroid carcinoma (FVPTC) and classical papillary thyroid carcinoma (CPTC) patients. The data of 69034 PTC patients were retrieved from the Surveillance, Epidemiology, and End Results (SEER) database. The 5-year mortality of CPTC and FVPTC patients receiving surgery, radiation and combination therapy were compared. The univariable and multivariable cox proportional risk models explored the associations between different treatments and the 5-year mortality in CPTC and FVPTC patients. The 5-year mortality of CPTC patients was 2.81% and FVPTC patients was 2.47%. Compared with CPTC receiving lobectomy and/or isthmectomy, those not receiving surgery were associated with increased risk of 5-year mortality [Hazards ratio (HR)=3.27, 95% confidence interval (CI): 2.55-4.20] while total thyroidectomy was correlated with reduced risk of 5-year mortality (HR=0.67, 95%CI: 0.55-0.80). Radioactive iodine (RAI) was linked with decreased risk of 5-year mortality in CPTC patients (HR=0.57, 95%CI: 0.50-0.65). CPTC patients undergoing both surgery and radiation were related to decreased risk of 5-year mortality compared with those receiving surgery only (HR=0.55, 95%CI: 0.48-0.63). CPTC patients receiving neither surgery nor radiation (HR=4.53, 95%CI: 3.72-5.51) or those receiving radiation (HR=1.98, 95%CI: 1.13-3.48) were correlated with elevated risk of 5-year mortality. The elevated risk of 5-year mortality in FVPTC patients was reduced in those undergoing RAI (HR=0.63, 95%CI: 0.51-0.76). In conclusion, combination therapy was associated with decreased risk of 5-year mortality in CPTC and FVPTC patients, which might provide a reference for the management of these patients.

Risk-stratified Distant Metastatic Thyroid Cancer with Clinicopathological Factors and BRAF/TERT Promoter Mutations

OBJECTIVE

To assess the prognostic value of clinicopathological factors as well as BRAF and TERT promoter mutations in predicting distant metastasis in patients with papillary thyroid cancer.

DESIGN

The status of BRAF and TERTp mutations were available in 1,208 thyroid cancer patients who received thyroidectomy at Jiangyuan Hospital Affiliated to Jiangsu Institute of Nuclear Medicine from January 2008 to December 2021. Based on inclusion criteria, 99 distant metastasis thyroid cancers (DM-TCs) and 1055 patients without DM (Non-DM-TCs) were retrospectively reviewed.

RESULTS

After univariate and multivariate analyses, a risk model was established for DM prediction based on factors: T3/T4 stage, lymph node metastasis (LNM) number over 5, and BRAF/TERT mutations (TLBT). It was defined based on the number of TLBT factors: low risk (no risk factor, n=896), intermediate risk (1 risk factor, n=199), and high risk (≥2 risk factors, n=59). Notably, compared with patients with low and intermediate risks, patients assigned to high TLBT risk have a shorter time of DM disease-free survival. Except for gene mutation, other factors were also included in the 2015 American Thyroid Association (ATA) risk guideline. Comparing with the ATA risk category, this risk model showed a better performance in predicting DM-TCs.

CONCLUSIONS

This study proposes a TLBT risk classifier consisting of T3/T4 stages, LNM (n>5), and BRAF+TERTp mutations for predicting DM-TCs. TLBT risk stratification may help clinicians make personalized treatment management and follow-up strategies.

Primary tumour iodine avidity in relation to uptake in persistent metastatic disease in papillary and poorly differentiated thyroid cancer

PURPOSE

Patients with persistent or recurrent papillary and poorly differentiated thyroid cancer can be effectively treated with radioiodine, if the tumour tissue is iodine-avid. However, iodine-avidity status is often unknown at the time of initial radioiodine treatment, limiting any adaptive approach. This study aimed to clarify the relationship between pre-therapeutic iodine avidity in primary tumour tissue, initial lymph node metastases and iodine uptake in subsequent metastases.

METHODS

Iodine avidity was prospectively assessed pre-therapeutically in 35 patients by injection of tracer amounts of iodine-131 two days prior to surgery. Iodine concentrations in resected tissue samples were measured, enabling accurate and histologically verifiable iodine avidity data for both primary tumour and initial lymph node metastases. Iodine uptake in persistent metastatic disease was assessed by review of radiology, and treatment response was examined through journal studies.

RESULTS

Out of data from 35 patients, 10 had persistent disease at presentation or during follow-up (range 19-46 months). Four patients had non-avid persistent metastatic disease, all with low iodine avidity in their primary tumours and initial lymph node metastases. Patients with low pre-therapeutic iodine avidity did not appear to have greater risk of persistent disease.

CONCLUSION

The results indicate a close link between pre-therapeutically measured iodine concentrations in primary tumours with iodine avidity of any subsequent metastases.

Automated diagnosis and management of follicular thyroid nodules based on the devised small-dataset interpretable foreground optimization network deep learning: a multicenter diagnostic study

BACKGROUND

Currently, follicular thyroid carcinoma (FTC) has a relatively low incidence with a lack of effective preoperative diagnostic means. To reduce the need for invasive diagnostic procedures and to address information deficiencies inherent in a small dataset, we utilized interpretable foreground optimization network deep learning to develop a reliable preoperative FTC detection system.

METHODS

In this study, a deep learning model (FThyNet) was established using preoperative ultrasound images. Data on patients in the training and internal validation cohort ( n =432) were obtained from Ruijin Hospital, China. Data on patients in the external validation cohort ( n =71) were obtained from four other clinical centers. We evaluated the predictive performance of FThyNet and its ability to generalize across multiple external centers and compared the results yielded with assessments from physicians directly predicting FTC outcomes. In addition, the influence of texture information around the nodule edge on the prediction results was evaluated.

RESULTS

FThyNet had a consistently high accuracy in predicting FTC with an area under the receiver operating characteristic curve (AUC) of 89.0% [95% CI 87.0-90.9]. Particularly, the AUC for grossly invasive FTC reached 90.3%, which was significantly higher than that of the radiologists (56.1% [95% CI 51.8-60.3]). The parametric visualization study found that those nodules with blurred edges and relatively distorted surrounding textures were more likely to have FTC. Furthermore, edge texture information played an important role in FTC prediction with an AUC of 68.3% [95% CI 61.5-75.5], and highly invasive malignancies had the highest texture complexity.

CONCLUSION

FThyNet could effectively predict FTC, provide explanations consistent with pathological knowledge, and improve clinical understanding of the disease.

Radioactive iodine therapy strategies for distinct types of differentiated thyroid cancer: a propensity score-matched analysis

Background

The management guidelines of radioactive Iodine (RAI) therapy for distinct types of differentiated thyroid carcinoma (DTC) were the same in clinical practice. However, in distinct types DTC, differences in RAI avidity and response existed and the effect of RAI therapy could not be equated.

Methods

DTC patients' data in SEER database were extracted to perform retrospective analysis. The differences between case group and control group were compared by chi-square tests. We used Kaplan-Meier statistics and Cox regression analyses to investigate cancer-specific survival (CSS). Propensity score-matched was performed to make 1:1 case-control matching.

Results

105195 patients who receiving total thyroidectomy were identified in SEER database. Compared to papillary thyroid carcinoma (PTC) (52.3%), follicular thyroid carcinoma (FTC) (63.8%) and oncocytic carcinoma of thyroid (OCA) (64.4%) had higher rates of RAI therapy. In the multivariable Cox regression model, RAI therapy was independent prognosis factor in PTC but not in OCA and FTC. In subgroup analysis, RAI therapy could improve prognosis in PTC when gross extrathyroidal extension or lymph node metastases or early survival when distant metastases (DM) were presented. However, OCA and FTC patients with DM rather than regional lesions only could benefit from RAI therapy. High-risk patients receiving RAI therapy showed a better prognosis in PTC but not in OCA and FTC.

Conclusion

RAI therapy was an effective treatment for DTC and should be considered individually in PTC, OCA and FTC patients. Our results provided further guideline for treatment selection in DTC.

Strategies for Radioiodine Treatment: What’s New

Radioiodine treatment (RAI) represents the most widespread and effective therapy for differentiated thyroid cancer (DTC). RAI goals encompass ablative (destruction of thyroid remnants, to enhance thyroglobulin predictive value), adjuvant (destruction of microscopic disease to reduce recurrences), and therapeutic (in case of macroscopic iodine avid lesions) purposes, but its use has evolved over time. Randomized trial results have enabled the refinement of RAI indications, moving from a standardized practice to a tailored approach. In most cases, low-risk patients may safely avoid RAI, but where necessary, a simplified protocol, based on lower iodine activities and human recombinant TSH preparation, proved to be just as effective, reducing overtreatment or useless impairment of quality of life. In pediatric DTC, RAI treatments may allow tumor healing even at the advanced stages. Finally, new challenges have arisen with the advancement in redifferentiation protocols, through which RAI still represents a leading therapy, even in former iodine refractory cases. RAI therapy is usually well-tolerated at low activities rates, but some concerns exist concerning higher cumulative doses and long-term outcomes. Despite these achievements, several issues still need to be addressed in terms of RAI indications and protocols, heading toward the RAI strategy of the future.

Non-Iodine-Avid Disease Is Highly Prevalent in Distant Metastatic Differentiated Thyroid Cancer With Papillary Histology

CONTEXT

Patients with radioactive iodine (RAI) refractory metastatic differentiated thyroid cancer (DTC) have poor prognosis. Early identification of RAI refractoriness may improve care.

OBJECTIVE

This work aimed to characterize DTC patients with distant metastases (DM) at diagnosis who presented with non-iodine-avid disease.

METHODS

Retrospective analyses of DTC patients with DM at diagnosis who presented between 2012 and 2020 were performed. Iodine uptake in DM was correlated with tumor histology and mutational profile. The difference in uptake between BRAFV600E-like (BVL) and RAS-like (RL) cancers based on insights from The Cancer Genome Atlas was evaluated.

RESULTS

Among 78 patients, 48.7% had negative uptake in DM on the first posttherapy scan. Negative scans were highly prevalent in papillary thyroid carcinoma (PTC) with papillary architecture, PTC with BRAFV600E mutation, and PTC with both BRAFV600E and TERT promoter mutations (71.1%, 80.9%, and 100%, respectively). BVL and RL tumors exhibited distinct uptake patterns with negative scan prevalence of 76.9% and 14.3% (P = .005). Multivariate logistical regression confirmed high odds of negative uptake in BVL tumors with either BVL mutations or papillary architecture, 19.8 (95% CI, 2.72-144), and low odds of negative uptake in RL tumors with either RL mutations or follicular architecture, 0.048 (95% CI, 0.006-0.344), after adjusting for age, sex, race, RAI preparation method, bone metastases, and RAI dose. Patients with negative scans were significantly older (62.4 vs 47.0 years, P = .03).

CONCLUSION

Among DTC patients with DM at diagnosis, non-iodine-avid disease is highly prevalent in patients with BVL cancers, particularly with BRAFV600E and TERT promoter mutations, and is associated with an older age. Better strategies are needed to improve RAI treatment response for these patients.

Hürthle Cell Carcinoma: Single Center Analysis and Considerations for Surgical Management Based on the Recent Literature

BACKGROUND

Hürthle cell carcinoma (HCC) of the thyroid is rare. There are contrasting data on its clinical behavior. The aim of this study was to describe clinic-pathological features and outcomes of HCC patients at our institution, in order to adapt our surgical management.

METHODS

We retrospectively studied 51 cases of HCC treated at the interdisciplinary endocrine center of the University Hospital of Cologne, Germany between 2005 and 2020.

RESULTS

Patients median age was 63 years (range 29-78) with 64.7% of cases being female. Primary treatment included surgery and postoperative radioiodine therapy with 3.7 GBq in all patients. Surgery consisted of total thyroidectomy in all cases and additional central lymphadenectomy in 90.2% of cases. The median number of harvested lymph nodes was 11 (range 2-31). Lymph node involvement was found in two (4.3%) pT4a tumors. In all other cases (95.7%), central lymphadenectomy was prophylactic and lymph nodes were free of metastasis in final histopathology. Twelve (23.5%) patients with incomplete biochemical response to primary treatment were diagnosed with structural relapse during the course of disease, for which seven (58.4%) underwent resection of isolated cervical metastasis. Histopathology revealed soft tissue implants in all cases and cervical surgery led to biochemical and radiologic cure in only two (28.5%) cases. Five (41.6%) patients developed metastatic disease, followed by systemic therapy in two patients. Vascular invasion of the primary tumor was significantly associated with relapse (p<0.01).

CONCLUSIONS

Recurrence of HCC was common in this study. Given the low rate of lymph node metastases both in this study and in recent literature and the nature of relapse (soft tissue instead of nodal metastasis), the benefit of routine prophylactic central lymph node dissection for HCC remains unclear, especially in the absence of vascular invasion from the primary tumor.

Radioiodine Refractory Follicular Thyroid Cancer and Surgery for Cervical Relapse

Compared to its more common counterpart papillary thyroid cancer (PTC), follicular thyroid cancer (FTC) has a less favorable outcome, due to its higher incidence of distant metastases and advanced stages at diagnosis. Despite radioiodine (RAI) avidity, metastatic FTC often progresses after radioiodine treatment (RAIT). We aimed at evaluating the indications and outcomes of surgery for cervical relapse of radioiodine refractory FTC. Patients receiving RAIT between 2005 and 2015 at the University Hospital of Cologne, Germany, were screened. Patients with FTC were identified. Demographics, clinic-pathologic characteristics, treatment, and outcome of patients diagnosed with RAI refractory FTC, who underwent cervical surgery in the course of disease, were analyzed. FTC accounted for 8.8% of all thyroid carcinomas undergoing RAIT. In 35.2% of FTC patients, disease persisted or recurred despite a cumulative mean RAI activity of 18.7 GBq ± 11.6 (follow-up 83.5 ± 56.7 months). Distant metastases were diagnosed in 75% of these patients, as bone (57.6%), lung (54.6%), and liver metastases (12.1%). Cervical relapse occurred in 63.6% of these patients and was treated in 57.1% with surgery with, and without, external beam radiation therapy (EBRT). Despite surgery and EBRT, in 75% of patients, cervical relapse recurred again. In conclusion, surgery for cervical radioiodine refractory FTC relapse is often performed in metastatic setting. With and without EBRT, cure is rare, although metastases can appear radioiodine avid. Early biological marker and systemic treatments for these patients are still needed.

Advances in Functional Imaging of Differentiated Thyroid Cancer

Simple Summary

Since the 1940s, radioactive iodine has been used for functional imaging and for treating patients with differentiated thyroid cancer (DTC). During this long-lasting experience, the use of iodine isotopes evolved, especially during the last years due to improved knowledge of thyroid cancer biology and improved performances of imaging tools. The present review summarizes recent advances in the field of functional imaging and theragnostic approach of DTC.

Abstract

The present review provides a description of recent advances in the field of functional imaging that takes advantage of the functional characteristics of thyroid neoplastic cells (such as radioiodine uptake and FDG uptake) and theragnostic approach of differentiated thyroid cancer (DTC). Physical and biological characteristics of available radiopharmaceuticals and their use with state-of-the-art technologies for diagnosis, treatment, and follow-up of DTC patients are depicted. Radioactive iodine is used mostly with a therapeutic intent, while PET/CT with ¹⁸F-FDG emerges as a useful tool in the diagnostic management and complements the use of radioactive iodine. Beyond ¹⁸F-FDG PET/CT, other tracers including ¹²⁴I, ¹⁸F-TFB and ⁶⁸Ga-PSMA, and new methods such as PET/MR, might offer new opportunities in selecting patients with DTC for specific imaging modalities or treatments.