Prolongation of tumour volume doubling time (midDT) is associated with improvement in disease-specific survival in patients with rapidly progressive radioactive iodine refractory differentiated thyroid cancer selected for molecular targeted therapy

Prognostic value of tumor volume doubling time in lung-metastatic adenoid cystic carcinoma

OBJECTIVES

Lung metastases in adenoid cystic carcinoma (ACC) usually have indolent growth and the optimal timing to start systemic therapy is not established. We assessed ACC lung metastasis tumor growth dynamics and compared the prognostic value of time to progression (TTP) and tumor volume doubling time (TVDT).

METHODS

The study included ACC patients with ≥1 pulmonary metastasis (≥5 mm) and at least 2 chest computed tomography scans. Radiology assessment was performed from the first scan showing metastasis until treatment initiation or death. Up to 5 lung nodules per patient were segmented for TVDT calculation. To assess tumor growth rate (TGR), the correlation coefficient (r) and coefficient of determination (R2) were calculated for measured lung nodules. TTP was assessed per RECIST 1.1; TVDT was calculated using the Schwartz formula. Overall survival was analyzed using the Kaplan-Meier method.

RESULTS

The study included 75 patients. Sixty-seven patients (89%) had lung-only metastasis on first CT scan. The TGR was overall constant (median R2 = 0.974). Median TTP and TVDT were 11.2 months and 7.5 months. Shorter TVDT (<6 months) was associated with poor overall survival (HR = 0.48; p = 0.037), but TTP was not associated with survival (HR = 1.02; p = 0.96). Cox regression showed that TVDT but not TTP significantly correlated with OS. TVDT calculated using estimated tumor volume correlated with TVDT obtained by segmentation.

CONCLUSION

Most ACC lung metastases have a constant TGR. TVDT may be a better prognostic indicator than TTP in lung-metastatic ACC. TVDT can be estimated by single longitudinal measurement in clinical practice.

Assessment of Pulmonary Metastasis in Differentiated Thyroid Carcinoma: Value of HRCT Correlation with Functional Imaging

Pulmonary metastases in thyroid carcinoma demonstrates varying imaging characteristics and disease biology and the outcome. The valuable complimentary role of high-resolution CT (HRCT) in conjunction with functional imaging such as radioiodine scan has been discussed and illustrated in this review along with the varied clinical and imaging presentations of lung metastases from differentiated thyroid cancer (DTC). A multi-modality patient-specific diagnostic approach and awareness about the atypical presentations helps in early identification as well as effective management of these patients, and especially in certain situations that could need multi-disciplinary management. While HRCT of the lungs as an added tool provides detailed visualization of the lung parenchyma, in the era of hybrid imaging, the routine adoption of SPECT-CT in patients with pulmonary metastases (in diagnostic or post-treatment settings) could provide equivalent or even incremental information from further management viewpoint.

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.

Emerging drugs for the treatment of radioactive iodine refractory papillary thyroid cancer

INTRODUCTION

The most frequent radioactive (RAI) refractory thyroid cancers are papillary thyroid carcinoma, followed by poorly differentiated thyroid carcinoma. They are rare and lethal. In recent years, significant therapeutic progress has been achieved.

AREAS COVERED

This paper offers insights on refractoriness to RAI treatment and the optimization of treatment initiation and treatment choice. Clinical trials performed with anti-angiogenic kinase inhibitors and with targeted inhibitors in patients with BRAF, RAS mutation or RET, TRK or ALK fusion are discussed.

EXPERT OPINION

These treatments provide high response rates. Anti-angiogenic kinase inhibitors improve median progression-free-survival; however, their benefit in terms of overall survival has been shown in only few subsets of patients. Treatment sequencing is challenging; in the absence of targetable abnormality, lenvatinib should be used as first line treatment. Options for second line treatment include lenvatinib (if not given at first line), cabozantinib or the addition of an anti-checkpoint antibody. In patients with a targetable abnormality, specific inhibitors, might be used as first line treatment and lenvatinib as second line or vice-versa. Further studies are needed, based on documented genomic and immunologic characteristics of the tumor to assess the potential role of combination and redifferentiation therapy.

Exploratory Analysis to Predict Optimal Tumor Burden for Starting Lenvatinib in Patients With Radioiodine-Refractory Differentiated Thyroid Cancer

Background

We previously reported that a high tumor burden is a prognostic factor based on an analysis of 26 patients with radioactive iodine-refractory differentiated thyroid cancer (RR-DTC) who were treated with lenvatinib. However, the optimal tumor burden for starting lenvatinib still remains to be defined. The aim of this retrospective study was to further explore in the same patient cohort the optimal timing for the start of lenvatinib by focusing on the pre- and post-treatment tumor burden.

Methods

The 26 patients were treated with lenvatinib from 2012 to 2017. We explored the optimal timing for the start of lenvatinib by comparing the characteristics of long-term responders who were defined as patients with progression-free survival ≥ 30 months and non-long-term responders.

Results

Long-term responders had a smaller post-treatment tumor burden at maximum shrinkage than non-long-term responders. Further, post-treatment tumor burden had a strong linear correlation with baseline tumor burden. We created an estimation formula for baseline tumor burden related to prognosis, using these regression lines. Patients with a sum of diameters of target lesions < 60 mm or maximum tumor diameter < 34 mm at baseline were estimated to have significantly better survival outcomes.

Conclusions

We found a strong linear correlation between pre- and post-treatment tumor burden. Our results suggested a cut-off value for baseline tumor burden for long-term prognosis among patients treated with lenvatinib.

Clinical Indications for Treatment with Multi-Kinase Inhibitors in Patients with Radioiodine-Refractory Differentiated Thyroid Cancer

Differentiated thyroid cancer is usually a slow-growing disease, even if the patients develop distant metastasis. For recurrent or metastatic disease, radioactive iodine therapy is a standard treatment. However, the disease gradually progresses in some of the patients and can ultimately develop into life-threatening conditions. For patients with progressive radioactive iodine-refractory differentiated thyroid cancer (RR-DTC), multi-kinase inhibitors (MKIs) including sorafenib and lenvatinib prolonged progression-free survival compared with placebo in pivotal randomized phase 3 trials, although the benefit in overall survival has not been clearly confirmed, possibly because the patients who received placebo were permitted to cross-over to lenvatinib upon disease progression. Moreover, the adverse events related to MKIs were not negligible. Therefore, the optimal timing of MKI initiation has long been controversial, and physicians should consider various patient and disease factors. Herein, we comprehensively review the clinical factors that can be helpful in determining the initiation of MKIs for patients with RR-DTC.

Personalized treatment for differentiated thyroid cancer: current data and new perspectives

More conservative and personalized treatment options have been developed in recent years to face the rising diagnosis of low-risk differentiated thyroid carcinoma (DTC). The present review describes the change towards a more risk-adapted management either in the treatment or in the follow-up of DTC. Particular attention is given to the innovations introduced by the latest guidelines for low-risk tumors, starting from the most appropriate extension of surgery up to the postoperative management. The emerging role of active surveillance for low-risk microcarcinoma is discussed, as well as the development of percutaneous strategies in the setting of malignant thyroid disease. The recent use of approved new systemic target therapies for advanced radioiodine refractory thyroid cancer is reported, together with the description of new compounds in trial. Finally, we provide some considerations to improve the risk evaluation in a presurgical setting, especially related to the rising role of genetics, to enable better risk-based cancer management and personalized treatment choices.

Structural Doubling Time Predicts Overall Survival in Patients with Medullary Thyroid Cancer in Patients with Rapidly Progressive Metastatic Medullary Thyroid Cancer Treated with Molecular Targeted Therapies

Purpose: To evaluate the impact of structural disease progression of metastatic lesions after initial surgery on overall survival (OS) of patients presenting with metastatic medullary thyroid cancer (MTC). We used tumor volume doubling time (TVDT) as a marker of structural disease progression and aimed to correlate the average structural tumor volume doubling time (midDT) with OS in MTC patients after initial surgery. Methods: In this retrospective study, we examined the clinical characteristics; average tumor volume doubling times of neck, lung, and liver metastasis; and disease-specific survival of patients with metastatic MTC. Results: Tumor growth is constant in MTC metastasis, irrespective of location of the metastasis. The median correlation coefficient (r) and the coefficient of determination (r²) were similar in lung metastasis (r = 0.91, r² = 0.95) and liver metastasis (r = 0.88, r² = 0.94), and comparable in neck metastasis (r = 0.73, r² = 0.85). Patients with metastatic MTC with a midDT ≤1 year have a worse prognosis than those with higher midDT (p = 0.002). Those with midDT ≤1 year had a median OS of 11.1 years [confidence interval (CI) 7.4-14.8 years]. In contrast, patients with midDT 1-3 years had a median OS of 16.5 years [CI 10.3-22.6 years]. All patients with midDT ≥3 survived by the end of the follow-up period. Preliminary results suggest that measurement of midDT can predict response to molecular targeted therapies. Conclusions: In conclusion, TVDT is a strong predictor of OS in patients with recurrent or metastatic MTC, can be used as a marker of progression, and potentially can help select patients who may benefit from molecular targeted therapy.

Estimating the Growth Rate of Lung Metastases in Differentiated Thyroid Carcinoma: Response Evaluation Criteria in Solid Tumors or Doubling Time?

Background: Estimating the growth rate of lung metastases for the treatment of patients with metastases of differentiated thyroid carcinoma (DTC) is important. This study aimed to evaluate survival outcomes according to different criteria for estimating the growth rate of lung metastases. Methods: Patients with macronodular (≥1 cm) lung metastases of DTC who underwent total thyroidectomy and high-dose radioactive iodine therapy between 1995 and 2013 were enrolled. The time to progressive disease (PD) by the Response Evaluation Criteria in Solid Tumors (RECIST), average tumor volume doubling time of the two dominant target lung lesions (midDT), and thyroglobulin doubling time (TgDT) were measured in each patient, and their association with disease-specific survival (DSS) was evaluated. Results: Forty-four patients with target lung metastatic nodules with an initial maximal diameter of 1.3 cm (median) were followed-up for a median of 6.8 years after the diagnosis of lung metastases. Based on RECIST, 12 patients (27.3%) showed fast tumor progression, with time to PD <1 year. When assessed by midDT, nine patients (20.5%) had midDT ≤1 year, showing rapid tumor progression. Seven of 33 patients (21.2%) who were negative for thyroglobulin antibody had midDT <1 year. Growth rates assessed by all three criteria were significantly associated with DSS. However, midDT had the highest predictive value for DSS, with a proportion of variation explained of 33.6%. Five-year DSS was 29.6% in patients with midDT ≤1 year, 50.0% in patients with time to PD <1 year, and 42.9% in patients with TgDT <1 year. Conclusions: Among the different criteria for estimating the growth rate of metastases in patients with lung metastases of DTC, midDT was the most powerful for predicting DSS, in comparison with RECIST and TgDT. Performing at least three serial chest computed tomography scans during the first year from the diagnosis of lung metastases can facilitate early detection of patients with rapid tumor progression and provide objective guidance for initiation of systemic therapy.

2019 European Thyroid Association Guidelines for the Treatment and Follow-Up of Advanced Radioiodine-Refractory Thyroid Cancer

The vast majority of thyroid cancers of follicular origin (TC) have a very favourable outcome, but 5-10% of cases will develop metastatic disease. Around 60-70% of this subset, hence less than 5% of all patients with TC, will become radioiodine refractory (RAI-R), with a significant negative impact on prognosis and a mean life expectancy of 3-5 years. Since no European expert consensus or guidance for this challenging condition is currently available, a task force of TC experts was nominated by the European Thyroid Association (ETA) to prepare this document based on the principles of clinical evidence. The task force started to work in September 2018 and after several revision rounds, prepared a list of recommendations to support the treatment and follow-up of patients with advanced TC. Criteria for advanced RAI-R TC were proposed, and the most appropriate diagnostic tools and the local, systemic and palliative treatments are described. Systemic therapy with multikinase inhibitors is fully discussed, including recommendations on how to start it and at which dosage, on the duration of treatment, and on the management of side effects. The appropriate relationship between the specialist and the patient/family as well as ethical issues are covered. Based on the available studies and on personal experience, the experts provided 39 recommendations aimed to improve the management of advanced RAI-R TCs. Above all of them is the indication to treat and follow these patients in a specialized setting which allows the interaction between several specialists in a multidisciplinary team.

Differentiated Thyroid Cancer, From Active Surveillance to Advanced Therapy: Toward a Personalized Medicine

Differentiated thyroid cancer (DTC) is the most frequent endocrine malignancy and represents the most rapidly increasing cancer diagnosis worldwide. In the last 20 years, this increase has been mostly due to a higher detection of small papillary thyroid cancers, with doubtful effects on patients' outcome. In fact, despite this growth, cancer-related death remained stable over the years. The growing detection of microcarcinomas associated to the indolent behavior of these cancers led to the development of strategies of active surveillance in selected centers of different countries. Moreover, toward a more personalized approach in the management of DTC patients, surgical treatments became more conservative, favoring less extensive options in patients at low risk of recurrence. The rise in lobectomy in low-risk cases and the need to avoid further therapies, with controversial impact on recurrences and cancer-related death in selected intermediate risk cases, led to reconsider the use of radioiodine treatment, too. Since clinicians aim to treat different patients with different modalities, the cornerstone of DTC follow-up (i.e., thyroglobulin, thyroglobulin autoantibodies, and neck ultrasound) should be interpreted consistently with this change of paradigm. The introduction of novel molecular target therapies (i.e., tyrosine kinase inhibitors), as well as a better understanding of the mechanisms of immune checkpoint inhibitor therapies, is radically changing the management of patients with advanced DTC, in whom no treatment option was available. The aim of this review is to analyze the most recent developments of the management of DTC, focusing on several key issues: active surveillance strategies, initial treatment, dynamic risk re-stratification, and therapeutic options in advanced DTC.