Natural history of small radioiodine-avid bone metastases that have no structural correlate on imaging studies

Metastasectomy of spinal lesions from thyroid carcinomas

Patients with differentiated thyroid carcinomas (DTCs) have a favourable long-term survival. Spinal metastases (SMs) cause a decline in performance status (PS), directly affecting mortality and indirectly preventing the use of systemic therapies. Metastasectomy is indicated, if feasible, as it yields the best local tumour control. Our study aimed to examine the long-term clinical outcomes of metastasectomy for SMs of thyroid carcinomas. We collected data on 22 patients with DTC (16 follicular and six papillary carcinomas) and one patient with medullary carcinoma who underwent complete surgical resection of SMs at our institution between July 1992 and July 2017, with a minimum postoperative follow-up of five years. The cancer-specific survival (CSS) from the first spinal metastasectomy to death or the last follow-up was determined using Kaplan-Meier analysis. Potential factors associated with survival were evaluated using the log-rank test. We analyzed the clinical parameters and outcome data, including pre- and postoperative disability (Eastern Cooperative Oncology Group PS 3), lung and non-spinal bone metastases, and history of radioiodine and kinase inhibitor therapies. Lung and other bone metastases at the time of surgery were observed in ten and eight patients, respectively. Three patients experienced local tumour recurrences at the operated site. The five- and ten-year CSS rates in the 22 patients with DTC were 77% and 52%, respectively. Pre- and postoperative disability and operative site tumour recurrence were identified as risk factors for short postoperative survival. Metastasectomy for resectable SM from DTC yielded favourable results and has the potential to improve survival.

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.

Locoregional progression-free survival of bone metastases from differentiated thyroid cancer

To evaluate the locoregional progression-free survival (LPFS) of bone metastatic lesions from differentiated thyroid cancer (DTC) after radioiodine therapy (RAIT) and to define its influencing factors, we performed a retrospective cohort analysis of 89 patients with bone metastases from DTC who received RAIT in our department over a 17-year period. The median follow-up time was calculated using the reverse Kaplan-Meier method. The log-rank test and a multivariate Cox proportional hazards regression model were performed in the analysis of prognostic indicators for LPFS. In this research, the median follow-up time for all patients was 47 (95% CI, 35.752-58.248) months, and that for patients with no progression was 42 months. The longest follow-up time was 109 months. The median LPFS time was 58 (95% CI, 32.602-83.398) months, and the 3- and 5-year LPFS probabilities were 57.8 and 45.1%, respectively. Multivariate analysis revealed bone structural changes as an independent risk factor for LPFS (P= 0.004; hazard ratio, 49.216; 95% CI, 3.558-680.704). Furthermore, the non-total-lesion uptake subgroup presented a worse LPFS than the total-lesion uptake subgroup in patients with structural bone lesions (P = 0.027). RAIT can improve the LPFS of radioiodine-avid bone metastases from DTC, especially those without bone structural changes.

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

PURPOSE

Bone metastases (BM) from differentiated thyroid carcinoma (DTC) impact negatively the quality of life and the life expectancy of patients. The aim of the study was (a) to evaluate the overall survival (OS) and prognostic factors of OS and (b) to assess predictive factors of complete BM response (C-BM-R) using radioiodine treatment (RAI) either alone or in association with focal treatment modalities.

METHODS

A total of 178 consecutive DTC patients harbouring BM, treated between 1989 and 2015, were enrolled in this retrospective study conducted in two tertiary referral centers. OS analysis was performed for the whole cohort, and only the 145 considered non-RAI refractory patients at BM diagnosis were evaluated for C-BM-R following RAI.

RESULTS

The median OS from BM diagnosis was 57 months (IQR: 24-93). In multivariate analysis, OS was significantly reduced in the case of T4 stage, ¹⁸FDG uptake by the BM and RAI refractory status. Among the 145 DTC considered non-RAI refractory patients at BM diagnosis, 46 patients (31.7%) achieved a C-BM-R following RAI treatment, either alone in 32 (18%) patients or in association with focal BM treatment modalities in 14. The absence of extra-skeletal distant metastasis and of ¹⁸FDG uptake in BM were predictive for C-BM-R.

CONCLUSIONS

In nearly one-third of DTC patients with RAI avid BM, RAI alone or in combination with BM focal treatment can induce C-BM-R. The presence of ¹⁸FDG uptake in BM is associated with an absence of C-BM-R and with a poor OS. ¹⁸FDG PET-CT should be performed when BM is suspected.

Current Management of Bone Metastases from Differentiated Thyroid Cancer

Simple Summary

Patients with bone metastases (BMs) from differentiated thyroid carcinoma (DTC) can live longer than those with BMs from other cancers. BMs from DTC create destructive lesions and easily cause intractable pain and neurological symptoms, including paralysis. These symptoms related to BMs affect mortality directly and indirectly by hampering the application of systemic therapies. Therefore, long-term local control of BMs in patients with DTC is desired, especially in patients with single or a small number of metastases. Local treatments for BMs have recently become advanced and sophisticated in surgery, radiotherapy, and percutaneous procedures. These therapies, either alone or in combination with other treatments, can effectively improve, or prevent the deterioration of, the performance status and quality of life of patients with DTC-BM. Among local therapies, complete surgical resection and stereotactic radiosurgery are the mainstay for achieving long-term control of DTC-BM.

Abstract

After the lung, the skeleton is the second most common site of distant metastases in differentiated thyroid carcinoma (DTC). Patients with osteolytic bone metastases (BMs) from thyroid carcinoma often have significantly reduced performance status and quality of life. Recent advancements in cancer therapy have improved overall survival in multiple cancer subtypes, including thyroid cancer. Therefore, long-term local control of thyroid BMs is desired, especially in patients with a single metastasis or oligometastases. Here, we reviewed the current management options for DTC-BMs and especially focused on local treatments for long-term local tumor control from an orthopedic tumor surgeon’s point of view. Metastasectomy and stereotactic radiosurgery can be performed either alone or in combination with radioiodine therapy and kinase inhibitors to cure skeletal lesions in selected patients. Percutaneous procedures have been developed in recent years, and they can also have a curative role in small BMs. Recent advancements in local therapies have the potential to provide not only long-term local tumor control but also a better prognosis.

Bone metastases from differentiated thyroid carcinoma: current knowledge and open issues

Bone represents the second most common site of distant metastases in differentiated thyroid cancer (DTC). The clinical course of DTC patients with bone metastases (BM) is quite heterogeneous, but generally associated with low survival rates. Skeletal-related events might be a serious complication of BM, resulting in high morbidity and impaired quality of life. To achieve disease control and symptoms relief, multimodal treatment is generally required: radioiodine therapy, local procedures-including surgery, radiotherapy and percutaneous techniques-and systemic therapies, such as kinase inhibitors and antiresorptive drugs. The management of DTC with BM is challenging: a careful evaluation and a personalized approach are essential to improve patients' outcomes. To date, prospective studies focusing on the main clinical aspects of DTC with BM are scarce; available analyses mainly include cohorts assembled over multiple decades, small samples sizes and data about BM not always separated from those regarding other distant metastases. The aim of this review is to summarize the most recent evidences and the unsolved questions regarding BM in DTC, analyzing several key issues: pathophysiology, prognostic factors, role of anatomic and functional imaging, and clinical management.

RADTHYR: an open-label, single-arm, prospective multicenter phase II trial of Radium-223 for the treatment of bone metastases from radioactive iodine refractory differentiated thyroid cancer

Purpose

This is the first prospective trial evaluating the efficacy of alpha emitter Radium-223 in patients with bone metastases from radioactive iodine (RAI) refractory (RAIR) differentiated thyroid cancer.

Methods

RADTHYR is a multicenter, single-arm prospective Simon two-stage phase II trial (NCT02390934). The primary objective was to establish the efficacy of three administrations of 55 kBq/kg of Radium-223 by ¹⁸F-FDG PET/CT according to PERCIST criteria. Secondary objectives were to establish the efficacy of six administrations of Radium-223 by ¹⁸F-FDG PET/CT, ^99mTc-HMDP bone scan and ¹⁸FNa PET/CT, clinical benefits, changes in serum bone markers, thyroglobulin levels, and safety.

Results

Ten patients were enrolled between July 2015 and December 2017 (4 M; median age 74 years). Prior to Radium-223 administration, patients received a median RAI cumulative activity of 15 GBq (7.4–35.6), external radiation therapy (n = 9), bone surgery (n = 8), cimentoplasty (n = 5), and cryoablation (n = 2). ¹⁸F-FDG PET/CT showed stable disease (SD) in 4/10 and progressive disease (PD) in 6/10 cases after three administrations and SD in 4/10, PD in 5/10 cases, and 1/10 non-evaluable (NE) case after six administrations. After six injections, ^99mTc-HMDP bone scan showed SD in 9 cases and was NE in 1 case; ¹⁸FNa PET/CT showed SD in 8 cases, partial response (PR) in 1 case, and was NE in 1 case. No significant clinical benefits were reported during the study. A skeletal event occurred in 6 patients (median time without skeletal event of 12.1 months). Seventy-seven adverse events were reported during treatment (7 of grade 3–4). Three patients developed an acute myeloid, a promyelocytic, and a chronic myeloid leukemia after the last Radium-223 administration considered as drug-related.

Conclusion

The trial was stopped after interim analysis for lack of response of bone metastases from RAIR thyroid cancer to Radium-223. Severe hematological toxicity was observed in patients heavily pretreated with RAI and external radiation.

Trial registration number

NCT02390934. Registration date 18.03.2015.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00259-021-05229-y.

Tumor burden of persistent disease in patients with differentiated thyroid cancer: correlation with postoperative risk-stratification and impact on outcome

Background

In patients with differentiated thyroid cancer (DTC), tumor burden of persistent disease (PD) is a variable that could affect therapy efficiency. Our aim was to assess its correlation with the 2015 American Thyroid Association (ATA) risk-stratification system, and its impact on response to initial therapy and outcome.

Methods

This retrospective cohort study included 618 consecutive DTC patients referred for postoperative radioiodine (RAI) treatment. Patients were risk-stratified using the 2015 ATA guidelines according to postoperative data, before RAI treatment. Tumor burden of PD was classified into three categories, i.e. very small-, small- and large-volume PD. Very small-volume PD was defined by the presence of abnormal foci on post-RAI scintigraphy with SPECT/CT or ¹⁸FDG PET/CT without identifiable lesions on anatomic imaging. Small- and large-volume PD were defined by lesions with a largest size < 10 or ≥ 10 mm respectively.

Results

PD was evidenced in 107 patients (17%). Mean follow-up for patients with PD was 7 ± 3 years. The percentage of large-volume PD increased with the ATA risk (18, 56 and 89% in low-, intermediate- and high-risk patients, respectively, p < 0.0001). There was a significant trend for a decrease in excellent response rate from the very small-, small- to large-volume PD groups at 9–12 months after initial therapy (71, 20 and 7%, respectively; p = 0.01) and at last follow-up visit (75, 28 and 16%, respectively; p = 0.04). On multivariate analysis, age ≥ 45 years, distant and/or thyroid bed disease, small-volume or large-volume tumor burden and ¹⁸FDG-positive PD were independent risk factors for indeterminate or incomplete response at last follow-up visit.

Conclusions

The tumor burden of PD correlates with the ATA risk-stratification, affects the response to initial therapy and is an independent predictor of residual disease after a mean 7-yr follow-up. This variable might be taken into account in addition to the postoperative ATA risk-stratification to refine outcome prognostication after initial treatment.

Thermal-ablation of vertebral metastases prevents adverse events in patients with differentiated thyroid carcinoma

PURPOSE

To evaluate a strategy that used thermal-ablation of vertebral metastases (VM) to prevent vertebral related events (VRE) in patients with differentiated thyroid cancer (DTC).

METHODS

This single center study retrospectively reviewed records and post-operative imaging of all DTC patients treated with thermal-ablation for asymptomatic VMs. Rate of local tumor control at first post-operative imaging, 12 and 24 months after thermal-ablation and rate of VREs at 12 and 24 months among the treated VMs were reported. New VMs that occurred during the follow-up and were not considered for additional thermal-ablation were moniroted and VREs were reported.

RESULTS

Thermal-ablation was used to achieve local control of 41 VMs in 28 patients. Median post-treatment follow-up was 22 months [range: 12-80] and the mean delay for first post-operative imaging was 2 months [range: 0.6-7.5]. Local control at first post-operative imaging, 12 and 24 months was achieved in 87.8%, 82.9% and 75.6%, respectively. Among the treated VMs the rates of VRE was 7.3% at 2 years, significantly lower if local control was achieved at first post-operative imaging than if it was not (0% vs 30%, p = 0.011, OR = 0.184 [95%CI = 0.094-0.360]). After thermal-ablation procedures, 19 news VMs occurred in 11 patients (39.2%) with a median interval of 8 months [range 1-26] and remained untreated. Among these untreated VMs, the rate of VREs at 2 years was significantly higher compared to the treated VMs: (36.8% vs. 7.3%, p = 0.008, OR = 0.135, [95%CI = 0.030-0.607]).

CONCLUSION

local tumor control of VMs using thermal-ablation decreases the risk of VREs in DTC patients.

Clinical and prognostic role of detection timing of distant metastases in patients with differentiated thyroid cancer

PURPOSE

Distant metastases (DM) from DTC occur in 5-25% of cases and are correlated to lower survival; the prognostic significance of the temporal onset of DM is unclear. Our aim was to retrospectively analyze the prevalence of DM and to assess the prognostic role of the timing of manifestation of DM regarding the outcome.

MATERIALS AND METHODS

We included 174 patients (mean age 64 years). According to the time of manifestation, DM were divided in two groups: synchronous DM (SDM, n = 108) defined as metastases present at initial diagnosis and metachronous DM (MDM, n = 66) as diagnosed during follow-up. SDM were further sub grouped in pre-RAIT when diagnosed during pre-surgery work-up (n = 35) and baseline-RAIT when detected by first whole body scan after RAIT (n = 73). Disease-specific survival (DSS) was analyzed using the Kaplan-Meier method.

RESULTS

Total RAI activities and number of treatments were significantly higher in MDM, also loss of RAI avidity was more frequent in MDM. Forty-four patients died during follow-up, of which 41 were DTC-related deaths, 5-year and 10-year DSS were 80% and 56%. On univariate analysis MDM had significantly shorter DSS; also histotype and RAI avidity were significant risk factors of impaired survival. On multivariate analysis, only loss of RAI avidity remained as independent negative predictor (p = 0.043). Considering SDM, DSS was significantly shorter in pre-RAIT group than baseline-RAIT (p = 0.004). Instead there was no significant difference between pre-RAIT-SDM and MDM in survival outcome (p = 0.875).

CONCLUSIONS

In DTC with DM, loss of RAI uptake has an important role in survival. No significant difference in survival outcome was discovered between SDM and MDM; but, among SDM, pre-RAIT had significant shorter DSS than baseline-RAIT.

Treatment of refractory thyroid cancer

Distant metastases from thyroid cancer of follicular origin are uncommon. Treatment includes levothyroxine administration, focal treatment modalities with surgery, external radiation therapy and thermal ablation, and radioiodine in patients with uptake of ¹³¹I in their metastases. Two-thirds of distant metastases become refractory to radioiodine at some point, and when there is a significant tumor burden and documented progression on imaging, a treatment with a kinase inhibitor may provide benefits.

Comparison of Empiric Versus Whole-Body/-Blood Clearance Dosimetry-Based Approach to Radioactive Iodine Treatment in Patients with Metastases from Differentiated Thyroid Cancer

The optimal management of radioactive iodine (RAI) treatment in patients with metastatic thyroid cancer (TC) is still a matter of debate. Methods: We retrospectively analyzed 352 patients with RAI-avid metastatic well-differentiated TC treated with ¹³¹I by an empiric fixed activity of 3.7 GBq at Gustave Roussy (GR, n = 231) or by personalized activity (2.7-18.6 GBq) based on whole-body/-blood clearance (WB/BC) dosimetry at Memorial Sloan Kettering Cancer Center (MSKCC, n = 121). The primary endpoint was to compare overall survival (OS) in the 2 groups of patients by log-rank test. Results: Patients received a median cumulative activity of 14.8 GBq at GR and 24.2 GBq at MSKCC (P < 0.0001). The median follow-up after the diagnosis of metastases was 7.2 y (0.4-31 y). Five-year OS was 86.8% and 78.8% for patients treated at GR and at MSKCC, respectively (P < 0.01). However, there was no statistical difference in OS after correction for sex, age at the diagnosis of distant metastases, metastases site, and metastases extension between the 2 centers (P = 0.16). OS at 5 y was 96% and 96% for patients younger than 40 y with micrometastases, 70% and 65% for patients older than 40 y with macrometastases or multiple metastases, and 92% and 87% for younger patients with macrometastases or older patients with micrometastases treated at GR and MSKCC, respectively (P = not significant). Conclusion: Routine use of WB/BC dosimetry without lesional dosimetry provided no OS advantage when compared with empiric fixed RAI activity in the management of thyroid cancer patients with RAI-avid distant metastases.

Early prognostic factors at the time of diagnosis of bone metastasis in patients with bone metastases of differentiated thyroid carcinoma

OBJECTIVE

Bone is the second most common site of distant metastases from differentiated thyroid cancer (DTC). Patients with bone metastases were associated with poor clinical outcomes; however, their clinical courses are heterogeneous. The aim of this study is to evaluate early prognostic factors of patients with bone metastases from DTC at the time of diagnosis of bone metastasis.

METHODS

This retrospective study included 93 patients with bone metastases from DTC. We defined 'Pre-RAIT group' as patients whose bone metastases were detected before initial RAIT. The 'post-RAIT group' was defined as patients whose bone metastases were detected after initial RAIT or during the follow-up period.

RESULTS

Median age was 55.4years, and 55 patients (59%) had papillary thyroid cancer. Patients in the pre-RAIT group (n=32) demonstrated significantly poorer overall survival (OS) (HR=1.86, P=0.04) than those in the post-RAIT group. There was no significant difference in the OS according to the initial RAI avidity among all patients (P=0.18). RAI-avid bone metastases had better OS only in the pre-RAIT group (HR=0.23, P=0.01) but not in the post-RAIT group. In the post-RAIT group, older age (>45years), elevated serum thyroglobulin (Tg) level (>250ng/mL), and the presence of skeletal-related events (SREs) were significantly associated with poor OS. RAI avidity was not a significant prognostic factor in the post-RAIT group (P=0.33).

CONCLUSIONS

Patients whose bone metastases were diagnosed before initial RAIT demonstrate a poorer prognosis. RAI avidity is an early prognostic indicator in the pre-RAIT group. Old age, higher serum Tg levels, and SRE are associated with poor survival outcomes in the post-RAIT group.

Treatment of distant metastases from follicular cell-derived thyroid cancer

Distant metastases from thyroid cancer of follicular origin are uncommon. Treatment includes levothyroxine administration at suppressive doses, focal treatment modalities with surgery, external radiation therapy and thermal ablation, and radioiodine in patients with uptake of ¹³¹I in their metastases. Two thirds of distant metastases will become refractory to radioiodine at some point, and when there is a significant tumor burden and documented progression on imaging, a treatment with a kinase inhibitor may provide benefits.