Bone metastases from differentiated thyroid carcinoma: heterogenous tumor response to radioactive Iodine therapy and overall survival

A new therapeutic paradigm: radioiodine combined with lenvatinib for radioiodine-avid metastatic well-differentiated thyroid cancer

PURPOSE

Management of metastatic well-differentiated thyroid cancer (WDTC) remains challenging, with significant morbidity and mortality. Multidisciplinary treatment, along with high-dose radioiodine therapy (HDRI), remains a mainstay. Morbidity and mortality benefits are noted, with seldom complete response. The foremost concerns are HDRI side effects, radioiodine refractoriness, macronodular lung, and bone metastasis. Lenvatinib is a standard of care in radioiodine-refractory disease. However, it remains unexplored in radioiodine-avid metastatic WDTC. This study investigates the effect of lenvatinib with HDRI in improving disease control and progression in radioiodine-avid metastatic WDTC.

MATERIAL AND METHODS

Fifteen patients with metastatic WDTC were enrolled with or without prior HDRI. The disease burden was evaluated with imaging [whole-body radioiodine scan (WBRI), PET-computed tomography (CT), or CT] and serum thyroglobulin (Tg) measurement. After excluding contraindication, lenvatinib was given for 3 months, along with thyroxine suppression. Adverse effects were monitored. Thyroxin was withdrawn, and the patient underwent WBRI followed by HDRI. Treatment response was evaluated based on imaging [response evaluation criteria in solid tumors (RECIST), PET response criteria in solid tumors (PERCIST), and WBRI] and tumor marker (Tg) parameters.

RESULTS

The mean age was 52.0 ± 14.2 years. Lung and bone metastases were noted in (12, 80%) and 10 (66%) patients. Nine (60%) patients already had HDRI (242.5 ± 140.3 mCi). Lenvatinib was well-tolerated, with two-thirds of patients having grade I toxicities. During follow-up (14.79 ± 5.93 months), one patient died of pneumonia unrelated to WDTC. Tg level fell from 45 800.8 ± 69 283.9 [median: 7094.0, interquartile range (IQR): 988.3-114 397.0] to 10 672.5 ± 18 490.5 (median: 1796.0, IQR: 171.0-17 090.0) ng/ml. Tg fall was not associated (P > 0.05) with age, sex, histopathology, and previous HDRI. Partial response and stable disease were noted in 10 and four patients, respectively, based on imaging (PERSIST and RECIST criteria) and tumor marker levels. One patient had disease progression on Tg and imaging.

CONCLUSION

HDRI, in combination with lenvatinib, demonstrated potential benefits in radioiodine-avid metastatic WDTC. The combination treatment was well-tolerated. There was an unprecedented fall in tumor marker level and partial response on imaging by a single cycle of the therapy. While a small sample size limited the study, preliminary data suggest that the synergistic effect may improve disease control. Further investigation with a larger cohort is warranted to confirm findings and explore potential response predictors.

Excellent RAI therapeutic response on a patient presenting skull metastasis of follicular thyroid cancer after 15 years

Bone is the second most common site of metastasis for differentiated thyroid carcinoma (DTC). Bone metastasis (BMs) occur in about 10% of patients with DTC and is observed more often in follicular thyroid carcinoma (FTC) (7-28%) than papillary thyroid carcinoma (PTC) (1-7%). Bone metastasis is associated with unfavorable clinical outcomes mainly including skeletal-related events (SREs), such as pathologic fractures, bone pain, spinal cord compressions, and hypercalcemia, which negatively impact the quality of life of patients and reduce their life expectancy. Patients with BMs from DTC require comprehensive and multimodal treatment approaches, including radioiodine (RAI) therapy, palliative care, surgery, external beam radiotherapy, and targeted drug therapy. RAI therapy is the first-line treatment, despite being rather ineffective, especially in large BMs. The response to RAI therapy, either alone or in combination with BM focal treatment depends on iodine avidity. This study reports a rare case of metachronous skull bone metastasis from FTC in a 72-year-old female patient 15 years after initial treatment. The patient had an excellent response to RAI therapy, which resulted in the abnormal uptake disappearing. Following treatment, the patient has been disease-free for six years. This case confirms that a complete response to RAI treatment for BM depends on the degree of dedifferentiation of cancer cells, which highlights the need for long-term follow-up, especially for FTC patients.

Anaplastic transformation of metastatic papillary thyroid carcinoma lesion histologically mimicking a squamous cell carcinoma: A case report

INTRODUCTION

The incidence of anaplastic transformation of thyroid cancer from Papillary Thyroid Carcinoma (PTC) is a rare tumor event, which ranges from 1 to 2 % of all cases of thyroid malignancy. Anaplastic transformation is often reported in primary lesions, but is rarely found in metastatic lesions from Differentiated Thyroid Carcinoma (DTC).

PRESENTATION OF CASE

This case report reports a unique tumor process where a 70-year-old woman had a metastatic lesion in the Mandible from PTC which transformed into ATC with histological features resembling squamous cell carcinoma-type. Immunohistochemical examination was able to prove that the lesion in the Mandible is a type of undifferentiated Thyroid carcinoma (anaplastic) with a squamous pattern originating from PTC.

DISCUSSION

This type of tumor with histological variant images that resemble other types of tumors is a challenge for diagnosis and appropriate management, so understanding the variants of this type of ATC is important for better management.

CONCLUSION

Although rare, anaplastic transformation can occur in metastatic sites of PTC. This necessitates the need for early accurate diagnosis through IHC assessment and somatic mutation testing so that appropriate treatment can be delivered.

Current Advances in Radioactive Iodine-Refractory Differentiated Thyroid Cancer

BACKGROUND

Differentiated thyroid cancer (DTC) patients have an outstanding overall long-term survival rate, and certain subsets of DTC patients have a very high likelihood of disease recurrence. Radioactive iodine (RAI) therapy is a cornerstone in DTC management, but cancer cells can eventually develop resistance to RAI. Radioactive iodine-refractory DTC (RAIR-DTC) is a condition defined by ATA 2015 guidelines when DTC cannot concentrate RAI ab initio or loses RAI uptake ability after the initial therapy. The RAIR condition implies that RAI cannot reveal new met-astatic foci, so RAIR-DTC metabolic imaging needs new tracers. 18F-FDG PET/CT has been widely used and has demonstrated prognostic value, but 18F-FDG DTC avidity may remain low. Fibroblast activation protein inhibitors (FA-Pi)s, prostatic-specific membrane antigen (PSMA), and somatostatin receptor (SSTR) tracers have been proposed as theragnostic agents in experimental settings and Arg-Gly-Asp (RGD) peptides in the diagnostic trial field. Multi-targeted tyrosine kinase inhibitors are relatively new drugs approved in RAIR-DTC therapy. Despite the promising targeted setting, they relate to frequent adverse-event onset. Sorafenib and trametinib have been included in re-differentiation protocols aimed at re-inducing RAI accumulation in DTC cells. Results appear promising, but not excellent.

CONCLUSIONS

RAIR-DTC remains a challenging nosological entity. There are still controversies on RAIR-DTC definition and post-RAI therapy evaluation, with post-therapy whole-body scan (PT-WBS) the only validated criterion of response. The recent introduction of multiple diagnostic and therapeutic agents obliges physicians to pursue a multidisciplinary approach aiming to correct drug introduction and timing choice.

Evaluation of 188Re- IBA as a novel radiopharmaceutical for bone marrow ablation

In this study, Ibandronate as a third generation of bisphosphonates was labeled with rhenium-188 radionuclide. Production and quality control of 188Re-IBA radiopharmaceutical was investigated. The radiation absorbed dose of this radiopharmaceutical was evaluated for adult male based on biodistribution data in mice using the RADAR and Sparks and Aydogan methodologies. The 188Re-IBA was produced with more than 96% radiochemical purity. The highest value of %ID/g was related to bone with 7.11% at 12 h post-injection. About 48% of injected activity was cumulated on the surface of bone tissue 48 h post-injection. The imaging studies confirmed the biodistribution pattern. Radiation absorbed doses of red bone marrow and osteogenic cells were estimated to about 0.39 and 0.71 mGy MBq-1, respectively. The maximum administrated activity was obtained 73.1 MBq kg-1 (2.0 mCi kg-1) of body weight. Effective dose was evaluated about 0.09 mSv MBq-1. The results were compared with other clinically used bone pain palliation radiopharmaceuticals. It was concluded that the 188Re-IBA radiopharmaceutical has a great tendency to be absorbed in bone tissue and it can provide sufficient care for bone marrow ablation with low undesired dose to other normal organs.

SPECT/CT, PET/CT, and PET/MRI for Response Assessment of Bone Metastases

Recent developments in hybrid SPECT/CT systems and the use of cadmium-zinc-telluride (CZT) detectors have improved the diagnostic accuracy of bone scintigraphy. These advancements have paved the way for novel quantitative approaches to accurate and reproducible treatment monitoring of bone metastases. PET/CT imaging using [18F]F-FDG and [18F]F-NaF have shown promising clinical utility in bone metastases assessment and monitoring response to therapy and prediction of treatment response in a broad range of malignancies. Additionally, specific tumor-targeting tracers like [99mTc]Tc-PSMA, [68Ga]Ga-PSMA, or [11C]C- or [18F]F-Choline revealed high diagnostic performance for early assessment and prognostication of bone metastases, particularly in prostate cancer. PET/MRI appears highly accurate imaging modality, but has associated limitations notably, limited availability, more complex logistics and high installation costs. Advances in artificial intelligence (Al) seem to improve the accuracy of imaging modalities and provide an assistant role in the evaluation of treatment response of bone metastases.

Tumor Burden of Iodine-Avid Bone Metastatic Thyroid Cancer Identified via 18F-Sodium Fluoride PET/CT Imaging

BACKGROUND

Patients with differentiated thyroid cancer (DTC) are referred to radioactive 131I (RAI) therapy and post-therapy 131I whole-body scintigraphy (WBS) to identify local and/or remote metastases. Positron emission tomography (PET)/computed tomography (CT) imaging with 18F-fluoro-D-glucose (FDG) or 18F-sodium fluoride (NaF) may also be used with these patients for the evaluation of bone metastases. We compared the role of 18F-NaF PET/CT and 18F-FDG-PET/CT in patients with DTC and documented bone metastases at post-therapy WBS.

METHODS

Ten consecutive DTC patients with iodine avid bone metastasis at post-therapy WBS referred to 18F-NaF PET/CT and 18F-FDG PET/CT were studied. The findings of the three imaging procedures were compared for abnormal detection rates and concordance.

RESULTS

At post-therapy 131I WBS, all patients had skeletal involvement with a total of 21 bone iodine avid lesions. At 18F-FDG PET/TC, 19 bone lesions demonstrated increased tracer uptake and CT pathological alterations, while 2 lesions did not show any pathological finding. At 18F-NaF PET/CT, the 19 bone lesions detected at 18F-FDG PET/TC also demonstrated abnormal tracer uptake, and the other 2 bone iodine avid foci did not show any pathological finding.

CONCLUSIONS

In patients with DTC, 18F-NaF PET/CT did not obtain more information on the metastatic skeletal involvement than post-therapy 131I WBS and 18F-FDG PET/CT.

A long-term retrospective cohort-based risk-benefit analysis of augmenting total cumulative I-131 activity to 37GBq in differentiated thyroid cancer patients with skeletal metastases

OBJECTIVE

Skeletal metastases in differentiated thyroid cancer (DTC) patients are associated with poor prognosis. The objective was to determine the maximum I-131 cumulative activity that could be safely administered without compromising efficacy. The secondary objective was to identify other prognostic factors affecting survival outcomes.

MATERIALS AND METHODS

This was a retrospective cohort study done at a tertiary-care institution comprising of data from January 1990-June 2020. 489 DTC patients having skeletal metastases with ≥12 months follow-up were included. Ninety-six percent of patients had thyroidectomy followed by radioiodine therapy for skeletal metastases. All patients were on oral suppressive levothyroxine tablets. External beam radiotherapy (EBRT) and oral tyrosine kinase inhibitors were used whenever indicated. The main outcome measures were overall survival (OS), progression-free survival (PFS), and adverse-events.

RESULTS

There were 347 (71%) females and 324 (66%) had follicular carcinoma thyroid. Median follow-up was 78 (interquartile range, IQR: 37-153) months. 333 patients (68%) received ≤37GBq I-131 cumulative activity (group 1) and 156 patients (32%) received >37GBq cumulative RAI activity (group 2). Overall median OS and PFS were 74 (95% confidence interval (CI): 62.2-85.8) and 48 (95%CI: 40.5-55.4) months, respectively. The 5-, 10-, 15- and 20-year estimated overall survival probabilities were 55.7%, 28.4%, 14% and 8.3%, respectively. On multivariate analysis, age(<55years) (p<0.001), female gender(p = 0.01), cumulative I-131 activity >37GBq (p<0.001) and EBRT(p = 0.001) were favourably associated with OS; no factors were significantly associated with PFS. The median OS for groups 1 & 2 were 51 versus 90 months (p<0.001) & median PFS for groups 1 & 2 were 45 versus 53 months respectively (p = 0.9). However, cumulative activity >37GBq resulted in more adverse events (2.4%), particularly bone marrow suppression (3.5%).

CONCLUSION

For better survival outcomes, cumulative I-131 activity upto 37GBq could be administered with acceptable toxicity to DTC patients with skeletal metastases.

Bone metastases from differentiated thyroid cancer: characteristics and prognostic factors in a multicenter series

Objective

The aim of this study is to describe the characteristics, survival and prognostic factors of a cohort of patients with bone metastases (BMs) from differentiated thyroid carcinoma (DTC).

Methods

This was a multicenter retrospective observational study including patients diagnosed with BMs from DTC between 1980 and 2021. A Cox regression was performed to study prognostic factors for 5- and 10-year survival. Kaplan-Meier and log-rank tests were performed for the survival analysis and comparison between groups.

Results

Sixty-three patients were evaluated. Median follow-up from BM diagnosis was 35 (15-68) months. About 30 (48.4%) patients presented with synchronous BMs. Regarding histology, 38 (60.3%) had the papillary variant. BMs were multiple in 32 (50.8%) patients. The most frequent location was the spine (60.3%). Other metastases were present in 77.8%, mainly pulmonary (69.8%). Concerning treatment, 54 (85.9%) patients received I131, with BM uptake in 31 (49.2%) and 25 (39.7%) received treatment with multikinase inhibitors. Regarding complications, 34 (54%) patients had skeletal-related events, 34 (54%) died and 5- and 10-year overall survival was 42.4% and 20.4%, respectively. Significant prognostic factors in the multivariate analysis were the presence of lymph node involvement (hazard ratio (HR): 2.916; 95% confidence interval (CI): 1.013-8.391; P = 0.047) and treatment with I131 (HR 0.214 (95% CI 0.069-0.665); P = 0.008) at 5 years, the presence of other metastases (HR 6.844. 95% CI 1.017-46.05; P = 0.048) and treatment with I131 (HR 0.23 (95% CI 0.058-0.913); P = 0.037) at 10 years.

Conclusions

Our study reflects the management of patients with bone metastases from differentiated thyroid carcinoma in real clinical practice in several centers in southern Spain. Overall survival at 5 and 10 years was lower in patients who were not treated with I131, had nodal involvement and/or had other metastases.

Clinical characteristics, treatment, and long-term outcome of patients with brain metastases from thyroid cancer

Brain metastases (BM) in patients with thyroid cancer (TC) are rare with an incidence of 1% for papillary and follicular, 3% for medullary and up to 10% for anaplastic TC (PTC, FTC, MTC and ATC). Little is known about the characteristics and management of BM from TC. Thus, we retrospectively analyzed patients with histologically verified TC and radiologically verified BM identified from the Vienna Brain Metastasis Registry. A total of 20/6074 patients included in the database since 1986 had BM from TC and 13/20 were female. Ten patients had FTC, 8 PTC, one MTC and one ATC. The median age at diagnosis of BM was 68 years. All but one had symptomatic BM and 13/20 patients had a singular BM. Synchronous BM at primary diagnosis were found in 6 patients, while the median time to BM diagnosis was 13 years for PTC (range 1.9-24), 4 years for FTC (range 2.1-41) and 22 years for the MTC patient. The overall survival from diagnosis of BM was 13 months for PTC (range 1.8-57), 26 months for FTC (range 3.9-188), 12 years for the MTC and 3 months for the ATC patient. In conclusion, development of BM from TC is exceedingly rare and the most common presentation is a symptomatic single lesion. While BM generally constitute a poor prognostic factor, individual patients experience long-term survival following local therapy.

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.