(18)F-fluorodeoxyglucose positron emission tomography to assess response after radiation therapy in anaplastic thyroid cancer

Anaplastic thyroid cancer: Genetic roles, targeted therapy, and immunotherapy

Anaplastic thyroid cancer (ATC) stands as the most formidable form of thyroid malignancy, presenting a persistent challenge in clinical management. Recent years have witnessed a gradual unveiling of the intricate genetic underpinnings governing ATC through next-generation sequencing. The emergence of this genetic landscape has paved the way for the exploration of targeted therapies and immunotherapies in clinical trials. Despite these strides, the precise mechanisms governing ATC pathogenesis and the identification of efficacious treatments demand further investigation. Our comprehensive review stems from an extensive literature search focusing on the genetic implications, notably the pivotal MAPK and PI3K-AKT-mTOR signaling pathways, along with targeted therapies and immunotherapies in ATC. Moreover, we screen and summarize the advances and challenges in the current diagnostic approaches for ATC, including the invasive tissue sampling represented by fine needle aspiration and core needle biopsy, immunohistochemistry, and 18F-fluorodeoxyglucose positron emission tomography/computed tomography. We also investigate enormous studies on the prognosis of ATC and outline independent prognostic factors for future clinical assessment and therapy for ATC. By synthesizing this literature, we aim to encapsulate the evolving landscape of ATC oncology, potentially shedding light on novel pathogenic mechanisms and avenues for therapeutic exploration.

Functional imaging in thyroid cancer patients with metastases and therapeutic implications

Functional imaging plays a central role in the management of thyroid cancer patients. In patients with a differentiated thyroid cancer (DTC), radioactive iodine (RAI) is used mostly with a therapeutic intent, either post-operatively or as the first line systemic treatment in patients with known structural disease. A whole body scan is performed a few days after the RAI administration, and this procedure is very sensitive to detect all tumor foci with RAI uptake. PET/CT with ¹⁸F-FDG complements the use of RAI at the initial evaluation of patients with high-risk DTC, during follow-up in those with rising serum thyroglobulin levels over time, for the work-up of patients with documented structural disease and for assessing the efficacy of focal or systemic treatment modalities. ¹⁸F-FDG uptake is a prognostic indicator in all these clinical conditions. A dosimetric approach with ¹²⁴I PET/CT showed encouraging results. Several functional imaging modalities are currently available for medullary thyroid carcinoma (MTC) patients. ¹⁸F-FDG-PET/CT may be sensitive in MTC patients with high FDG uptake that signals aggressive disease. ¹⁸F-DOPA is the most sensitive imaging technique to visualize small tumor foci, and is also highly specific in patients with a known MTC, but should be complemented by a CT scan of the chest and by a MRI of the liver to detect small metastases.

Anaplastic Thyroid Carcinoma: An Update

Anaplastic thyroid carcinoma (ATC) is a rare and undifferentiated form of thyroid cancer. Its prognosis is poor: the median overall survival (OS) of patients varies from 4 to 10 months after diagnosis. However, a doubling of the OS time may be possible owing to a more systematic use of molecular tests for targeted therapies and integration of fast-track dedicated care pathways for these patients in tertiary centers. The diagnostic confirmation, if needed, requires an urgent biopsy reread by an expert pathologist with additional immunohistochemical and molecular analyses. Therapeutic management, defined in multidisciplinary meetings, respecting the patient's choice, must start within days following diagnosis. For localized disease diagnosed after primary surgical treatment, adjuvant chemo-radiotherapy is recommended. In the event of locally advanced or metastatic disease, the prognosis is very poor. Treatment should then involve chemotherapy or targeted therapy and decompressive cervical radiotherapy. Here we will review current knowledge on ATC and provide perspectives to improve the management of this deadly disease.

18F-Fluorodeoxyglucose-Positron Emission Tomography/Computed Tomography for Other Thyroid Cancers: Medullary, Anaplastic, Lymphoma and So Forth

Positron emission tomography/computed tomography (PET/CT) with ¹⁸F-fluorodeoxyglucose (FDG) is used in staging, restaging, and evaluation of therapy response in many cancers as well as differentiated thyroid carcinomas especially in non-iodine avid variants. Its potential in less frequent thyroid tumors like medullary, anaplastic thyroid cancers, thyroid lymphoma and metastatic tumors of the thyroid however, is not well established yet. The aim of this review is to provide an overview on the recent applications and indications of ¹⁸F-FDG PET/CT in these tumors and to focus on the controversies in the clinical setting.

Radiation therapy dose is associated with improved survival for unresected anaplastic thyroid carcinoma: Outcomes from the National Cancer Data Base

BACKGROUND

The outcomes of patients with unresected anaplastic thyroid carcinoma (ATC) from the National Cancer Data Base (NCDB) were assessed, and potential correlations were explored between radiation therapy (RT) dose and overall survival (OS).

METHODS

The study cohort was comprised of patients who underwent either no surgery or grossly incomplete resection. Correlates of OS were explored using univariate analysis and multivariable analysis (MVA).

RESULTS

In total, 1288 patients were analyzed. The mean patient age was 70.2 years, 59.7% of patients were women, and 47.6% received neck RT. The median OS was 2.27 months, and 11% of patients remained alive at 1 year. A positive RT dose-survival correlation was observed for the entire study cohort, for those who received systemic therapy, and for those with stage IVA/IVB and IVC disease. On MVA, older age (hazard ratio [HR], 1.317; 95% confidence interval [CI], 1.137-1.526), ≥ 1 comorbidity (HR, 1.587; 95% CI, 1.379-1.827), distant metastasis (HR, 1.385; 95% CI, 1.216-1.578), receipt of systemic therapy (HR, 0.637; 95% CI, 0.547-0.742), and receipt of RT compared with no RT (<45 grays [Gy]:HR, 0.843; 95% CI, 0.718-0.988; 45-59.9 Gy: HR, 0.596; 95% CI, 0.479-0.743; 60-75 Gy: HR, 0.419; 95% CI, 0.339-0.517) correlated with OS. The RT dose-survival correlation for patients who received higher (60-75 Gy) versus lower (45-59.9 Gy) therapeutic doses was confirmed by propensity-score matching.

CONCLUSIONS

Survival was poor in this cohort of patients with unresected ATC, and more effective therapies are needed. However, the association of RT dose with OS highlights the importance of identifying patients with unresected ATC who may still yet benefit from multimodal locoregional treatment that incorporates higher dose RT. Cancer 2017;123:1653-1661. © 2017 American Cancer Society.