Active surveillance in differentiated thyroid cancer: a strategy applicable to all treatment categories response

Currently, the differentiated thyroid cancer (DTC) management is shifted toward a tailored approach based on the estimated risks of recurrence and disease-specific mortality. While the current recommendations on the management of metastatic and progressive DTC are clear and unambiguous, the management of slowly progressive or indeterminate disease varies according to different centers and different physicians. In this context, active surveillance (AS) becomes the main tool for clinicians, allowing them to plan a personalized therapeutic strategy, based on the risk of an unfavorable prognosis, and to avoid unnecessary treatment. This review analyzes the main possible scenarios in treated DTC patients who could take advantage of AS.

Yttrium-90 transarterial radioembolization for liver metastases from medullary thyroid cancer

Objectives

Liver metastases occur in 45% of patients with advanced metastatic medullary thyroid cancer (MTC). Transarterial radioembolization (TARE) has been proposed to treat liver metastases (LM), especially in neuroendocrine tumors. The aim of this study was to investigate the biochemical (calcitonin and carcino-embryonic antigen) and objective response of liver metastases from MTC to TARE.

Methods

TARE is an internal radiotherapy in which microspheres loaded with β-emitting yttrium-90 (90Y) are delivered into the hepatic arteries that supply blood to LM. Eight patients with progressive multiple LM underwent TARE and were followed prospectively. They were clinically, biochemically and radiologically evaluated at 1, 4, 12 and 18 months after TARE.

Results

Two patients were excluded from the analysis due to severe liver injury and death due to extrahepatic disease progression, respectively. One month after TARE, a statistically significant (P = 0.02) reduction of calcitonin was observed in all patients and remained clinically relevant during follow-up; reduction of CEA, although not significant, was found in all patients. Significant reduction of liver tumor mass was observed 1, 4 and 12 months after TARE (P = 0.007, P = 0.004, P = 0.002, respectively). After 1 month, three of six patients showed partial response (PR) and three of six stable disease (SD) according to RECIST 1.1, while five of six patients had a PR and one of six a SD according to mRECIST. The clinical response remained relevant 18 months after TARE. Excluding one patient, all others showed only a slight and transient increase in liver enzymes.

Conclusions

TARE is effective in LM treatment of MTC. The absence of severe complications and the good tolerability make TARE a valid therapeutic strategy when liver LM are multiple and progressive.

[18F]-FDG-PET/CT Correlates With the Response of Radiorefractory Thyroid Cancer to Lenvatinib and Patient Survival

CONTEXT

18F-fluoro-2-deoxy-D-glucose positron emission tomography-computed tomography ([18F]-FDG-PET/CT)-positive metastatic lesions in radioiodine-refractory differentiated thyroid cancer (RAI-R DTC) have a poor prognosis and lenvatinib represents the best therapy.

OBJECTIVE

We investigated the role of [18F]-FDG-PET/CT in the evaluation of metabolic response and prediction of the outcome of RAI-R DTC patients treated with lenvatinib.

METHODS

Patients (n = 33) with progressive metastatic RAI-R DTC who were treated with lenvatinib were investigated at baseline and during follow-up with biochemical (thyroglobulin and thyroglobulin antibodies), morphological (whole-body CT scan) and metabolic ([18F]-FDG-PET/CT) evaluation.

RESULTS

Nineteen (57.6%) patients showed the greatest metabolic response at the first [18F]-FDG-PET/CT scan, performed after 4 weeks of lenvatinib, while 5/33 (15.1%) patients had this response later. Moreover, 66.7% of patients had both a metabolic response at the first [18F]-FDG-PET/CT scan and a morphological response at the first CT scan. We observed a correlation between the metabolic response at [18F]-FDG-PET/CT scan performed after 4 weeks of treatment and the biochemical response at the same time in 60.6% of patients. The median overall survival (OS) was significantly longer in patients with either a metabolic response at last [18F]-FDG-PET/CT (40.00 vs 8.98 months) or a morphological response at last CT scan (37.22 vs 9.53 months) than in those without response. Moreover, the OS was longer in patients with a metabolic response at [18F]-FDG-PET/CT performed after 4 weeks of treatment (36.53 vs 11.28 months).

CONCLUSIONS

Our data show that [18F]-FDG-PET/CT can early predict the response to lenvatinib and correlates with the OS of RAI-R DTC patients treated with this drug.

Prevalence and Risk Factors of Developing Fistula or Organ Perforation in Patients Treated with Lenvatinib for Radioiodine-Refractory Thyroid Cancer

INTRODUCTION

Tyrosine kinase inhibitors represent a better treatment in patients with radioiodine-refractory differentiated thyroid cancer (RAI-R DTC). Lenvatinib is usually well-tolerated, but sometimes, it is associated with serious and even life-threatening side effects. The aim of this study was to evaluate the prevalence of and the potential risk factors for fistula and/or organ perforation in RAI-R DTC patients treated with lenvatinib.

METHODS

This study included data from advanced and progressive RAI-R DTC patients treated with lenvatinib from February 2011 to February 2020 who were followed up at a single center. The clinical-pathological features and the biochemical and morphological results of the patients were collected at the time of starting lenvatinib and during the follow-up.

RESULTS

Fourteen of 95 (14.7%) locally advanced or metastatic RAI-R DTC patients treated with lenvatinib developed a fistula or organ perforation. Nine of 14 (64.3%) patients had tumor infiltration of the trachea, bronchus, esophagus, pleura, or bladder. Five of 14 (35.7%) had a bowel perforation, but only 2 had preexisting diverticulosis. Evaluation of the risk factors for developing a fistula or organ perforation showed that the presence of tumor infiltration and the tumor histology (papillary and poorly differentiated vs. follicular and Hurthle thyroid cancer) were significantly correlated with the development of a fistula or organ perforation (p = 0.003 and p = 0.02, respectively). In the subgroup of patients with tumor infiltration, we found that the papillary thyroid cancer histotype was the only potential predictor of fistula development. External beam radiation therapy (EBRT), the starting dose of lenvatinib, and the duration of treatment were not relevant for the development of fistula.

CONCLUSIONS

In metastatic thyroid cancer patients treated with lenvatinib, the presence of tumor infiltration and histological type should be considered as potential risk factors for the development of fistula or organ perforation, although they do not represent an absolute contraindication. Although EBRT and the presence of diverticulosis were not significantly associated with the development of fistula and organ perforation, they should be regarded as potential additional reasons for the development of these complications. According to our findings, there is no reason to start lenvatinib at a lower daily dose when tumor infiltration is present.

Thyroid Cancers: From Surgery to Current and Future Systemic Therapies through Their Molecular Identities

Differentiated thyroid cancers (DTC) are commonly and successfully treated with total thyroidectomy plus/minus radioiodine therapy (RAI). Medullary thyroid cancer (MTC) is only treated with surgery but only intrathyroidal tumors are cured. The worst prognosis is for anaplastic (ATC) and poorly differentiated thyroid cancer (PDTC). Whenever a local or metastatic advanced disease is present, other treatments are required, varying from local to systemic therapies. In the last decade, the efficacy of the targeted therapies and, in particular, tyrosine kinase inhibitors (TKIs) has been demonstrated. They can prolong the disease progression-free survival and represent the most important therapeutic option for the treatment of advanced and progressive thyroid cancer. Currently, lenvatinib and sorafenib are the approved drugs for the treatment of RAI-refractory DTC and PDTC while advanced MTC can be treated with either cabozantinib or vandetanib. Dabrafenib plus trametinib is the only approved treatment by FDA for BRAFV600E mutated ATC. A new generation of TKIs, specifically for single altered oncogenes, is under evaluation in phase 2 and 3 clinical trials. The aim of this review was to provide an overview of the current and future treatments of thyroid cancer with regards to the advanced and progressive cases that require systemic therapies that are becoming more and more targeted on the molecular identity of the tumor.

No difference in the outcome of metastatic thyroid cancer patients when using recombinant or endogenous TSH

OBJECTIVE

At present, recombinant TSH cannot be used for the treatment of metastatic differentiated thyroid cancer patients. The aim of this study was to evaluate if the type of TSH stimulation, recombinant or endogenous, had an impact on the outcome of these patients.

DESIGN AND METHODS

We compared the outcome of two propensity score-matched groups of metastatic patients, stimulated by either only recombinant TSH (n = 43) or only endogenous TSH (n = 34).

RESULTS

As expected from the matching procedure, the clinical-pathological features and the cumulative 131-I activities administered to the two groups were very similar. After 4 years of follow-up, 4% of patients were cured, 3% had biochemical disease and 93% had structural disease. However, 91% of patients obtained a clinical benefit from this therapy in terms of stabilization of the disease or complete remission or partial response. When considering the two groups separately, we did not find any difference in their outcome. When considering the response to 131-I therapy of the single type of metastases, 8% of lymph node metastases and 8% of lung metastases disappeared but none of the bone metastases. The response to 131-I therapy of the single type of metastases was similar when we looked at the two groups separately.

CONCLUSIONS

This study shows (i) an overall clinical benefit of the 131-I therapy, since the majority of patients remained affected but with a stable disease, and (ii) that the preparation with either recombinant or endogenous TSH has no impact on the 131-I therapy efficacy and the outcome of our two groups of patients.

MON-490 Calcitonin-Based Thyroidectomy Is a Safe Approach in Patients with Germline RET Mutation and Permits to Delay Surgery in Children

Introduction: Medullary thyroid cancer (MTC) arises from C cells secreting calcitonin. In familial MTC cases, a germline RET mutation is discovered in 98% of cases. Nowadays, an early diagnosis and radical surgery are the only curative approach. However, thyroidectomy in children is associated with a higher rate of surgical adverse events, compared to surgery in adults. The best clinical approach in patient harboring germline RET mutation (gene carriers, GC) is still undefined. Methods and materials: since 1994 to 2018 we identified 174 GC by RET screening. 56 GC underwent total thyroidectomy and lymph node dissection for the evidence of high calcitonin levels at the first clinical evaluation, whereas 27 GC underwent surgery for high stimulated calcitonin levels during the active surveillance (median 16 months, range 13-118). 90 GC are still in follow up. Results: In the group of 27 GC patients who underwent surgery during the active surveillance, 15 GC had only C cells hyperplasia (CCH) foci and 12 were affected by MTC. These carcinomas were all confined to the thyroid, without any lymph node and distant metastasis. All these patients are still in clinical remission, after a median follow-up of 4 years (range 1-11). At time of the surgery, the patients affected by MTC were significantly older than patients harboring only CCH (median 49 vs 30 years old, respectively). Among these 27 GC, 7 were diagnosed as GC when they were younger than 18 years (median 7 years old, range 2-18) and they underwent surgery after a median period of 3 years (range 1-10 years), when they were all older than 7 years. In this group, 6 of 7 were affected by CCH and only one case by a microMTC. There were not any persistent surgical adverse events and all of them are still in clinical remission. 41 of 90 GC, who are still in active surveillance, were younger than 18 years at time of RET screening: nowadays, 10/41 are older than 18 years and 15/41 are older than 14 years, all with calcitonin still in the normal range. Conclusions: we demonstrated that the calcitonin-based thyroidectomy is a safe approach in GC. Intriguingly, this approach seems to be interesting especially in children in order to perform still an early and safe surgery but when they are older, possibly adults.

Active Surveillance in Papillary Thyroid Microcarcinomas is Feasible and Safe: Experience at a Single Italian Center

CONTEXT

The dramatic rise in the incidence of thyroid cancer over the last 30 years is largely attributable to the increasing diagnosis of papillary microcarcinomas (mPTCs). Current guidelines endorse an observational management approach in properly selected cases.

OBJECTIVE

To evaluate the feasibility of active surveillance in mPTC in Italy, its impact on real life, and to identify risk factors of progression.

DESIGN AND SETTING

In 2014 we started a prospective-observational study of active surveillance in mPTC patients.

PATIENTS

Included patients demonstrated a single Thy4 or Thy5 thyroid nodule, with largest diameter ≤1.3 cm, and no suspicious laterocervical lymph nodes by neck ultrasonography. Of 185 eligible subjects, 50.3% (93/185) enrolled in the observational management protocol while the others opted for surgery and were excluded from this analysis.

INTERVENTION

Enrolled patients were followed with neck ultrasound at 6- to 12-month intervals. Disease progression was defined as the appearance of abnormal lymph nodes or nodule enlargement during follow-up. In these cases, patients were directed to surgery.

RESULTS

Three patients (3/93, 3%) showed clinical progression and required surgery. Another 19 patients (19/93, 20%) decided to transition to surgical intervention even though there was no evidence of disease progression. All operated patients had excellent response to initial treatment despite the delayed surgery.

CONCLUSIONS

Within an Italian medical context, active surveillance appears to be a feasible and safe alternative to immediate surgery in healthy mPTC patients. Only 3% of mPTC demonstrated disease progression during a median follow-up of 19 months (range 6-54) and importantly demonstrated excellent outcomes after surgical intervention in a short-term follow-up.

Protein kinase inhibitors for the treatment of advanced and progressive radiorefractory thyroid tumors: From the clinical trials to the real life

The last ten years have been characterized by the introduction in the clinical practice of new drugs named tyrosine kinase inhibitors for the treatment of several human tumors. After the positive conclusion of two international multicentric, randomized phase III clinical trials, two of these drugs, sorafenib and lenvatinib, have been recently approved and they are now available for the treatment of advanced and progressive radioiodine refractory thyroid tumors. We have been involved in most clinical trials performed with different tyrosine kinase inhibitors in different histotypes of thyroid cancer thus acquiring a lot of experience in the management of both drugs and their adverse events. Aim of this review is to give an overview of both the rationale for the use of these inhibitors in thyroid cancer and the major results of the clinical trials. Some suggestions for the management of treated patients in the real life are also provided.

Targeted Therapy in Thyroid Cancer: State of the Art

Thyroid cancer typically has a good outcome following standard treatments, which include surgery, radioactive iodine ablation for differentiated tumours and treatment with thyrotropine hormone-suppressive levothyroxine. Thyroid cancers that persist or recur following these therapies have a poorer prognosis. Cytotoxic chemotherapy or external beam radiotherapy has a low efficacy in these patients. 'Target therapy' with tyrosine kinase inhibitors (TKIs) represent an important therapeutic option for the treatment of advanced cases of radioiodine refractory (RAI-R) differentiated thyroid cancer (DTC), medullary thyroid cancer (MTC) and possibly for cases of poorly differentiated (PDTC) and anaplastic thyroid cancer (ATC). In the last few years, several TKIs have been tested for the treatment of advanced, progressive and RAI-R thyroid cancers and some of them have been recently approved for use in clinical practice: sorafenib and lenvatinib for DTC and PDTC; vandetanib and cabozantinib for MTC. The objective of this overview is to present the current status of the treatment of advanced DTC, MTC, PDTC and ATC with the use of TKIs by describing the benefits and the limits of their use. A comprehensive analysis and description of the molecular basis of these drugs and the new therapeutic perspectives are also reported. Some practical suggestions are also given for the management to the potential side-effects of these drugs.

Treatment of advanced thyroid cancer with targeted therapies: ten years of experience

Thyroid cancer is rare, but it is the most frequent endocrine malignancy. Its prognosis is generally favorable, especially in cases of well-differentiated thyroid cancers (DTCs), such as papillary and follicular cancers, which have survival rates of approximately 95% at 40 years. However, 15-20% of cases became radioiodine refractory (RAI-R), and until now, no other treatments have been effective. The same problems are found in cases of poorly differentiated (PDTC) and anaplastic (ATC) thyroid cancers and in at least 30% of medullary thyroid cancer (MTC) cases, which are very aggressive and not sensitive to radioiodine. Tyrosine kinase inhibitors (TKIs) represent a new approach to the treatment of advanced cases of RAI-R DTC, MTC, PDTC, and, possibly, ATC. In the past 10 years, several TKIs have been tested for the treatment of advanced, progressive, and RAI-R thyroid tumors, and some of them have been recently approved for use in clinical practice: sorafenib and lenvatinib for DTC and PDTC and vandetanib and cabozantinib for MTC. The objective of this review is to present the current status of the treatment of advanced thyroid cancer with the use of innovative targeted therapies by describing both the benefits and the limits of their use based on the experiences reported so far. A comprehensive analysis and description of the molecular basis of these therapies, as well as new therapeutic perspectives, are reported. Some practical suggestions are given for both the choice of patients to be treated and their management, with particular regard to the potential side effects.