Adjuvant External Beam Radiotherapy in Locally Advanced Differentiated Thyroid Cancer

Construction of a new tool for predicting cancer-specific survival in papillary thyroid cancer patients who have not received surgery

Background

The prevalence of papillary thyroid cancer is gradually increasing and the trend of youthfulness is obvious. Some patients may not be able to undergo surgery, which is the mainstay of treatment, due to physical or financial reasons. Therefore, the prediction of cancer-specific survival (CSS) in patients with non-operated papillary thyroid cancer is necessary.

Methods

Patients' demographic and clinical information was extracted from the Surveillance, Epidemiology, and End Results database. SPSS software was used to perform Cox regression analyses as well as propensity score matching analyses. R software was used to construct and validate the nomogram. X-tile software was used to select the best cutoff point for patient risk stratification.

Results

A total of 1319 patients were included in this retrospective study. After Cox regression analysis, age, grade, T stage, M stage, radiotherapy, and chemotherapy were used to construct the nomogram. C-index, calibration curves, and receiver operating characteristic curves all verified the high predictive accuracy of the nomogram. The decision curve analysis demonstrated that patients could gain clinical benefit from this predictive model. Survival curve analysis after propensity score matching demonstrated the positive effects of radiotherapy on CSS in non-operated patients.

Conclusion

Our retrospective study successfully established a nomogram that accurately predicts CSS in patients with non-operated papillary thyroid cancer and demonstrated that radiotherapy for operated patients can still help improve prognosis. These findings can help clinicians make better choices.

External beam radiation therapy for recurrent or residual thyroid cancer: What is the best treatment time and the best candidate for long-term local disease control?

INTRODUCTION

Cervical disease control might be challenging in advanced thyroid cancer (DTC). Indications for cervical external beam radiation therapy (EBRT) are controversial.

PURPOSE

To identify clinical and molecular factors associated with control of cervical disease with EBRT.

METHODS

Retrospective evaluation and molecular analysis of the primary tumor DTC patients who underwent cervical EBRT between 1995 and 2022 was performed.

RESULTS

Eighty adults, median age of 61 years, were included. T4 disease was present in 43.7%, lymph node involvement in 42.5%, and distant metastasis in 47.5%. Those with cervical progression were older (62.5 vs. 57.3, p = 0.04) with more nodes affected (12.1 vs. 2.8, p = 0.04) and had EBRT performed later following surgery (76.6 vs. 64 months, p = 0.05). EBRT associated with multikinase inhibitors showed longer overall survival than EBRT alone (64.3 vs. 37.9, p = 0.018) and better local disease control. Performing EBRT before radioiodine (RAI) was associated with longer cervical progression-free survival (CPFS) than was RAI before (67.5 vs. 34.5, p < 0.01). EBRT ≥2 years after surgery was associated with worse CPFS (4.9 vs. 34, p = 0.04). The most common molecular alterations were ERBB2, BRAF, FAT1, RET and ROS1 and TERT mutation was predictive of worse disease control after EBRT (p = 0.04).

CONCLUSION

Younger patients, with fewer affected nodes and treated earlier after surgery had better cervical disease control. Combination of EBRT with MKI improved OS. TERT mutation might indicate worse responders to EBRT; however, further studies are necessary to clarify the role of molecular testing in selecting candidates for cervical EBRT.

The modern landscape of radiotherapy in thyroid malignancies

Thyroid carcinoma is the most common malignancy of the endocrine system and accounts for nearly 1.5% of all new cancer cases in India. The incidence of thyroid cancers is on the rise secondary to multiple factors including the widespread use of radiological imaging. Surgery remains the cornerstone of treatment, and radioactive iodine therapy plays a pivotal role in differentiated thyroid cancer. Radiation therapy appears to be an underutilized treatment modality. In this review, we have summarized the role of radiation in the treatment of thyroid cancer.

Management of Recurrent Well-Differentiated Thyroid Carcinoma in the Neck: A Comprehensive Review

Surgery has been historically the preferred primary treatment for patients with well-differentiated thyroid carcinoma and for selected locoregional recurrences. Adjuvant therapy with radioactive iodine is typically recommended for patients with an intermediate to high risk of recurrence. Despite these treatments, locally advanced disease and locoregional relapses are not infrequent. These patients have a prolonged overall survival that may result in long periods of active disease and the possibility of requiring subsequent treatments. Recently, many new options have emerged as salvage therapies. This review offers a comprehensive discussion and considerations regarding surgery, active surveillance, radioactive iodine therapy, ultrasonography-guided percutaneous ablation, external beam radiotherapy, and systemic therapy for well-differentiated thyroid cancer based on relevant publications and current reference guidelines. We feel that the surgical member of the thyroid cancer management team is empowered by being aware and facile with all management options.

External beam radiotherapy for thyroid cancer: Patients, complications, and survival

BACKGROUND

Patterns of utilization of external beam radiation therapy (EBRT) in thyroid cancer are incompletely described. We characterize therapeutic intent, complications, and survival in thyroid cancer treated with EBRT.

METHODS

In this retrospective study of 105 thyroid cancer patients treated with EBRT at one institution (2008-2018), the primary outcome was overall survival. Secondary outcomes included incomplete treatment, emergency department (ED) visits, weight change, and gastrostomy placement.

RESULTS

Dominant histopathology was differentiated (44%), anaplastic (45%) and poorly-differentiated (11%) disease. EBRT was mainly utilized for locoregional control (differentiated 87%, poorly-differentiated 75%, anaplastic 92%). Palliative EBRT was more common in poorly-differentiated disease (42%). Weight loss was greater in aggressive/advanced disease (differentiated 10 lb, poorly-differentiated 27 lb, anaplastic 18 lb). Anaplastic cancer had higher rates of gastrostomy (34%) and lowest rates of treatment completion (83%). ED encounters were common (differentiated 44%, poorly-differentiated 50%, anaplastic 45%). Gastrostomy was associated with mortality on multivariable analysis in non-anaplastic malignancy.

CONCLUSIONS

EBRT was most frequently administered for locoregional control in thyroid cancer. Despite complications, the majority of patients completed EBRT therapy.

Propensity score matching analysis of adjuvant external-beam radiotherapy for the treatment of papillary thyroid carcinoma with other organ invasions

PURPOSE

The role of adjuvant external-beam radiotherapy (EBRT) in the treatment of locally advanced papillary thyroid carcinoma (PTC) remains controversial due to the lack of prospective data and the conflicting retrospective data. This study aimed to determine the benefits of adjuvant EBRT in patients with PTC and other organ invasions using propensity score matching to reduce the heterogeneity of the patient population.

METHODS

Data from patients with PTC with other organ invasions but no distant metastases who underwent surgery and adjuvant radioactive iodine (RAI) alone (Non-EBRT group) or adjuvant EBRT plus RAI (EBRT group) were retrospectively reviewed. Propensity matching was used to reduce heterogeneity. Survival outcomes and toxicities associated with EBRT were evaluated.

RESULTS

Between January 2005 and December 2019, 102 patients in the Non-EBRT group and 26 patients in the EBRT group were evaluated. In the 48 propensity score-matched patients, no significant differences in baseline characteristics between the Non-EBRT and EBRT groups were detected. The locoregional recurrence-free survival (LRRFS) and recurrence-free survival (RFS) rates were significantly higher in the EBRT group compared with the rates in the Non-EBRT group (5y-LRRFS: 100% vs. 74%, p = 0.003, 5y-RFS: 91% vs. 74%, p = 0.035). EBRT was well-tolerated, with no grade ≥ 3 toxicity, and all patients completed the therapy as planned.

CONCLUSION

Adjuvant EBRT plus RAI exhibited acceptable toxicity and improved LRRFS and RFS in patients with PTC with other organ invasions compared with RAI alone.

Effect of postoperative radiotherapy for patients with differentiated thyroid cancer

OBJECTIVE

We evaluated the efficacy and safety of postoperative radiotherapy (PORT) for differentiated thyroid cancer (DTC) with high risk features.

MATERIALS AND METHODS

This retrospective study analyzed 187 patients treated for DTC from 1985 to 2019. DTC referred to nonanaplastic thyroid cancer originating from follicular cells. PORT was defined as the administration of external beam radiation to the thyroid and regional lymph nodes following surgery for initially diagnosed DTC. The patients were included in the analysis if they received PORT or exhibited any of the following features: (a) pT4 or pN1b according to the 8th American Joint Committee on Cancer, (b) poorly differentiated thyroid cancer (PDTC), or (c) unfavourable variants such as anaplastic foci and etc. After 1:1 propensity matching, a total of 108 patients were analyzed according to PORT receipt. The median follow-up duration of the matched group was 10.4 years.

RESULTS

After matching, most of the variables became balanced, but the PORT group still had more PDTC and DTC with anaplastic foci. Radioactive iodine (RAI) was less frequently administered in the PORT group. PORT yielded a significantly higher 5-year locoregional recurrence free survival (LRFS) than the No PORT group (5-year LRFS 86.1% vs. 72.7%, p = 0.022), but the 10-year cancer specific survival (CSS) was similar between them (97.8% vs. 85.9%, p = 0.122). The multivariable analysis indicated that PORT was a favourable prognostic factor (Hazard ratio 0.3, 95% Confidence interval 0.1-0.8, p = 0.02) for LRFS, but not for CSS. Among 133 patients without PORT for initial disease, 39 of them received salvage surgery followed by salvage PORT. No severe toxicity after PORT was reported.

CONCLUSION

PORT reduced locoregional recurrence in DTC patients without severe toxicity. PORT can be an effective and safe treatment to improve locoregional control in DTC with high risk features. However, further study is warranted to identify those who can benefit from PORT.

Role of autophagy in tumor response to radiation: Implications for improving radiotherapy

Autophagy is an evolutionary conserved, lysosome-involved cellular process that facilitates the recycling of damaged macromolecules, cellular structures, and organelles, thereby generating precursors for macromolecular biosynthesis through the salvage pathway. It plays an important role in mediating biological responses toward various stress, including those caused by ionizing radiation at the cellular, tissue, and systemic levels thereby implying an instrumental role in shaping the tumor responses to radiotherapy. While a successful execution of autophagy appears to facilitate cell survival, abortive or interruptions in the completion of autophagy drive cell death in a context-dependent manner. Pre-clinical studies establishing its ubiquitous role in cells and tissues, and the systemic response to focal irradiation of tumors have prompted the initiation of clinical trials using pharmacologic modifiers of autophagy for enhancing the efficacy of radiotherapy. However, the outcome from the Phase I/II trials in many human malignancies has so far been equivocal. Such observations have not only precluded the advancement of these autophagy modifiers in the Phase III trial but have also raised concerns regarding their introduction as an adjuvant to radiotherapy. This warrants a thorough understanding of the biology of the cancer cells, including its spatio-temporal context, as well as its microenvironment all of which might be the crucial factors that determine the success of an autophagy modifier as an anticancer agent. This review captures the current understanding of the interplay between radiation induced autophagy and the biological responses to radiation damage as well as provides insight into the potentials and limitations of targeting autophagy for improving the radiotherapy of tumors.

Well-Differentiated Thyroid Cancer: Who Should Get Postoperative Radiation?

BACKGROUND

The mainstay of treatment of well-differentiated thyroid cancer (WDTC) is surgery followed by adjuvant radioactive iodine therapy. Postoperative radiation therapy (PORT) is rarely used.

OBJECTIVE

The aim of our study was to report our experience of patients with WDTC who were selected to receive PORT.

MATERIALS AND METHODS

After Institutional Review Board approval, patients who received PORT were identified from a departmental database of 6259 patients with WDTC treated with primary surgery from 1986 to 2015. We carried out propensity matching to compare outcomes with a cohort of patients who did not receive PORT. The main outcome of interest was central neck recurrence-free probability (CNRFP), while secondary outcomes were lateral neck recurrence-free probability (LNRFP), disease-specific survival (DSS), and overall survival (OS).

RESULTS

From 6259 patients, 32 (0.5%) patients with a median age of 65.2 years received PORT. Tall-cell variant papillary thyroid carcinoma was the most common pathology (45%). Patients who received PORT had no difference in CNRFP compared with patients treated without PORT (10-year CNRFP 88% vs. 73%; p = 0.18). Furthermore, patients who received PORT had superior LNRFP (10-year LNRFP 100% vs. 62%; p = 0.001) compared with the no-PORT cohort. Despite this, patients who received PORT had similar DSS (71% PORT vs. 75% no-PORT) and OS (65% PORT vs. 58% no-PORT group) as the no-PORT cohort.

CONCLUSIONS

Our data show that select patients who received PORT had improved locoregional recurrence-free probability; however, this did not translate into improved DSS and OS. At our institution, we recommend the use of PORT only in highly selected patients with locally advanced primary tumors who are deemed to have a high risk of central neck recurrence for which salvage surgery would result in unacceptable risk to the airway.

The role of external beam radiation therapy in the management of thyroid carcinomas: A retrospective study in Iran Cancer Institute

BACKGROUND

Thyroid cancers are histologically classified into three types; differentiated thyroid carcinoma (DTC), medullary thyroid carcinoma (MTC), and anaplastic thyroid carcinoma (ATC). Among the several therapeutic strategies for treatment and management of thyroid cancer, surgical resection in combination with radioactive iodine therapy (RAI) is indicated for moderate to high-risk differentiated thyroid cancer (DTC) patients- according to current guidelines. However, external radiation therapy (EBRT) can be a viable alternative treatment option for these patients and scarce evidence is available regarding the efficacy and effectiveness of EBRT on thyroid cancer.

AIM

This study aims at evaluating the role of EBRT in the management of thyroid carcinomas.

METHODS AND RESULTS

In this retrospective cohort study, the records of 59 patients with thyroid cancer were accessed who were treated by EBRT from 2008 to 2016. The indications for EBRT included unresectable primary (definitive) or loco-regional recurrences (salvage) not suitable for RAI, palliation for local disease or metastatic foci (palliative), and the adjuvant treatment for suspected residual disease following resection. Progression-free survival (PFS) and overall survival (OS) were calculated for different types of cancer. PFS was measured from the start of EBRT to the last uneventful follow-up, recurrence, or death. Kaplan-Meier model was used for the survival analysis. Fifty-nine patients were evaluated. The histopathology of the tumors was differentiated and poorly-differentiated, medullary and anaplastic thyroid carcinomas in 22 and 6, 15 and 16 patients, respectively. Twenty-seven patients received external beam radiotherapy (EBRT) as adjuvant therapy and 18 of the cases as palliative therapy while the remaining received salvage or definitive primary EBRT. The stage of patients' cancer was as follows: stage II in 3 and III in 1, IVA in 18 and IVB in 18 and IVC in 19. Stage-based median overall survival was 26 months for IVA, 44 for IVB, and 29 for IVC. The median PFS was 18, 22 and 21 months for stages IVA, IVB and IVC, respectively.

CONCLUSION

Based on our findings, EBRT may still play a role in the management of patients with thyroid carcinoma and should be considered in the armamentarium against thyroid cancers.

Technological Advancements in External Beam Radiation Therapy (EBRT): An Indispensable Tool for Cancer Treatment

Recent technological advancements have increased the efficacy of radiotherapy, leading to effective management of cancer patients with enhanced patient survival and improved quality of life. Several important developments like multileaf collimator, integration of imaging techniques like positron emission tomography (PET) and computed tomography (CT), involvement of advanced dose calculation algorithms, and delivery techniques have increased tumor dose distribution and decreased normal tissue toxicity. Three-dimensional conformal radiotherapy (3DCRT), intensity-modulated radiotherapy (IMRT), stereotactic radiotherapy, image-guided radiotherapy (IGT), and particle therapy have facilitated the planning procedures, accurate tumor delineation, and dose estimation for effective personalized treatment. In this review, we present the technological advancements in various types of EBRT methods and discuss their clinical utility and associated limitations. We also reveal novel approaches of using biocompatible yttrium oxide scintillator-photosensitizer complex (YSM) that can generate X-ray induced cytotoxic reactive oxygen species, facilitating X-ray activated photodynamic therapy (XPDT (external beam) and/or iXPDT (internal X-ray source)) and azido-derivatives of 2-deoxy-D-glucose (2-DG) as agents for site-specific radiation-induced DNA damage.

Postoperative external beam radiotherapy for locoregional control in iodine refractory differentiated thyroid cancer

Background

The role of postoperative external beam radiotherapy (EBRT) in patients with residual iodine refractory-differentiated thyroid cancer (IR-DTC) is still inconclusive. The aim of this retrospective study was to evaluate locoregional control (LRC) and overall survival (OS), and potential side effects after postoperative EBRT for both microscopic and macroscopic non-radically resected, locally advanced IR-DTC.

Methods

Between 1990 and 2016, 49 patients with locally advanced IR-DTC received EBRT for microscopic (R1; n = 28) or macroscopic (R2; n = 21) locoregional residual disease. For more insight into the added effect of EBRT, we performed an intrapatient sub-analysis in 32 patients who had undergone more than 1 surgical intervention, comparing LRC after primary, curative-intended surgery with LRC after repeated surgery plus EBRT. To estimate LRC and OS, we used Kaplan-Meier curves. From 2007 onward, we prospectively recorded toxicity data in our head and neck cancer database (n = 10).

Results

LRC rates 5 years after EBRT were higher for R1 (84.3%) than for R2 (44.9%) residual disease (P = 0.016). The 5-year OS rate after EBRT was 72.1% for R1 and 33.1% for R2 disease (P = 0.003). In the intrapatient analysis (n = 32), LRC rates were 6.3% 5 years after only initial surgery and 77.9% after repeated surgery with EBRT (P < 0.001). Acute toxicity was limited to grade I and II xerostomia, mucositis, and hoarseness; only one patient developed late grade III dysphagia.

Conclusions

Postoperative EBRT is associated with long-lasting LRC and OS with acceptable toxicity in patients with locally advanced IR-DTC, especially in microscopic residual disease.

External Radiotherapy for Locoregional Control in Thyroid Carcinoma

Most patients with well-differentiated thyroid cancers (WDTC) are adequately treated with surgery, radioactive iodine, and TSH suppression by thyroxine. External radiotherapy (ERT) is reserved for selected cases and for older patients. Some of the indications for ERT to neck include adjuvant treatment for gross or microscopic disease after surgery, palliation of locally advanced unresectable tumor, or as salvage for recurrent disease which is not amenable to surgery or does not uptake radioactive iodine. High radiation dose of at least 60Gy is required for locoregional control of gross or microscopic residual disease. As even patients with recurrent or metastatic disease can have long survival, it is important to minimize late radiation-induced morbidity without compromising local control. Modern ERT technique like intensity-modulated radiotherapy allows high radiation dose to be delivered to the large, complex target volume while protecting the adjacent critical normal structures like the trachea, larynx, esophagus, and cervical spinal cord.

Predictive Impact of Metastatic Lymph Node Burden on Distant Metastasis Across Papillary Thyroid Cancer Variants

Background: While numerous factors determine prognosis in papillary thyroid carcinoma (PTC), distant metastasis (M1) represents one of the most dire. Escalating nodal burden and aggressive histology may contribute to higher metastatic risk, but this relationship is poorly defined and challenging to anticipate. We evaluate the predictive impact of these histological features on predicting distant metastases at initial presentation. Methods: Univariate and multivariable logistic regression models of conventional and aggressive thyroid cancer variants (well-differentiated papillary thyroid carcinoma [WDPTC], diffuse sclerosing variant [DSV], tall cell variant [TCV], poorly differentiated thyroid cancer [PDTC], and anaplastic thyroid carcinoma [ATC]) identified via U.S. cancer registry data were constructed to determine associations between M1 status and quantitative nodal burden. Associations between metastatic lymph node (LN) number and M1 disease were modeled using univariate and multivariable logistic regression with interaction terms, as well as a linear continuous probability model. Results: Overall, M1 prevalence at disease presentation was 3.6% (n = 1717). When stratified by subtype, M1 prevalence varied significantly by histology (WDPTC [1.0%], DSV [2.3%], TCV [4.1%], PDTC [17.4%], ATC [38.4%] [p < 0.001]). For WDPTC, M1 prevalence escalated with metastatic LN number (0 LN+ [0.5%], 1-5 LN+ [2.0%], 6-10 LN+ [3.4%], >10 LN+ [5.5%] [p < 0.001]) and LN ratio (p < 0.001). A statistically significant interaction was observed between histology and increasing nodal burden for M1 risk. On multivariable analysis, each successive metastatic LN conferred increased M1 risk for WDPTC (odds ratio [OR] 1.06 [1.05-1.08], p < 0.001) and TCVs (OR 1.04 [1.02-1.07], p < 0.001). In contrast, other aggressive variants had a higher baseline M1 risk, but this did not vary based on the number of positive LN (DSV, OR 1.02 [0.95-1.10], p = 0.52; PDTC, OR 1.00 [0.98-1.02], p = 0.66; ATC, 1.00 [0.98-1.02], p = 0.97). Conclusions: Progressive nodal burden independently escalates the risk of distant metastasis in WDPTC and TCVs of PTC. Conversely, aggressive variants such as PDTC and ATC have substantial M1 risk at baseline and appear to be minimally affected by metastatic nodal burden. Consideration of these factors after surgery may help tailor clinical decision-making for treatment and surveillance. Further studies are warranted to calibrate the ideal management approach for these higher risk patient groups.

Initial Experience with Proton Beam Therapy for Differentiated Thyroid Cancer

Purpose

External beam radiotherapy is used in a subset of high-risk patients with differentiated thyroid cancer (DTC). Recurrent, radioactive iodine (RAI)-refractory DTC carries a poor prognosis. We report our initial experience of intensity-modulated proton therapy (IMPT) for recurrent, RAI-refractory DTC.

Patients and Methods

Fourteen patients with recurrent, RAI-refractory DTC were consecutively treated with IMPT from November 2016 to March 2020 at our multisite institution. Patient, tumor, and treatment characteristics were recorded. Overall survival and local-regional recurrence-free survival were recorded and estimated using the Kaplan-Meier method. Acute and late treatment-related toxicities were recorded based on the Common Terminology Criteria for Adverse Events version 5.0. Patients completed the European Organization for Research and Treatment of Cancer Quality of Life Head and Neck Module at baseline and after IMPT. Eleven patients were included in the final analysis.

Results

Median follow-up was 8 months (range, 3-40) for all patients. Median age at treatment with IMPT was 64 years (range, 40-77), and the majority were men (64%). Recurrent histologies included papillary (55%), Hurthle cell (36%), and poorly differentiated (9%) carcinoma; 1 patient had tall cell variant. Concurrent chemotherapy was not administered for any patient in this cohort. At 8 months, all patients were alive without local-regional failure. Acute grade 3 toxicities were limited to 1 patient with dysphagia, requiring feeding tube placement. Two patients experienced late grade 3 esophageal stenosis requiring dilation. There were no grade 4 or 5 toxicities. There were no differences in pretreatment versus posttreatment patient-reported outcomes in terms of dysphagia or hoarseness.

Conclusion

In our early experience, IMPT provided promising local-regional control for recurrent, RAI-refractory DTC. Further study is warranted to evaluate the long-term efficacy and safety of IMPT in this patient population.

Advancements in the treatment of differentiated thyroid cancer

Derived from follicular epithelial cells, differentiated thyroid cancer (DTC) accounts for the majority of thyroid malignancies. The threefold increase in DTC incidence over the last three decades has been largely attributed to advancements in detection of papillary thyroid microcarcinomas. Efforts to address the issue of overtreatment have notably included the reclassification of encapsulated follicular variant papillary thyroid cancers (EFVPTC) to non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). In the last 5 years, the overall management approach for this relatively indolent cancer has become less aggressive. Although surgery and radioiodine ablation remain the mainstay of DTC therapy, the role of active surveillance is being explored. Furthermore, the most recent American Thyroid Association (ATA) guidelines offer flexibility between lobectomy and total thyroidectomy for thyroid nodules between 1 cm and 4 cm in the absence of extrathyroidal extension or nodal disease. As our understanding of the natural history and molecular underpinnings of DTC evolves, so might our approach to managing low-risk patients, obviating the need for invasive intervention. Simultaneously, advances in interventional and systemic therapies have greatly expanded treatment options for high-risk surgical candidates and patients with widespread disease, and continue to be areas of active investigation. Continued research efforts are essential to improve our ability to offer effective individualized therapy to patients at all disease stages and to reduce the incidence of recurrent and progressive disease.

The Increased Risk of Thyroid Cancer-Specific Mortality With Tumor Size in Stage IVB Patients

Purpose: To investigate the risk-stratifying utility of tumor size and a threshold for further stratification on cancer-specific mortality of thyroid cancer (TC) patients in stage IVB.

Methods: One thousand three hundred and forty-five patients (620 males and 725 females) with initial distant metastasis over 55 years between 2004 and 2016 from Surveillance, Epidemiology, and End Results databases were investigated, with a median follow-up time of 23 months [interquartile range (IQR), 5–56 months] and a median age of 70 years (IQR, 63–77 years). TC-specific mortality rates were calculated under different classifications. Cox regressions were used to calculate hazard ratios (HRs) and Kaplan-Meier Analyses were conducted to investigate TC-specific survivals.

Results: In the whole cohort, patients with tumors >4 cm had the highest TC-specific mortality (67.9%, 330/486), followed by tumor size >1 cm but ≤ 4 cm (43.08%, 190/441), and tumor size ≤ 1 cm (32.69%, 34/104). Kaplan-Meier curves showed the increased tumor size was associated with a statistically significant decrease in TC-specific survival (P < 0.001). Papillary thyroid cancer (PTC) patients with tumors >4 cm had significantly higher hazard ratios (HRs) of 2.84 (1.72–4.70) and 3.11 (1.84–5.26) after adjusting age, gender, race, and radiation treatment, compared with patients with tumors ≤ 1 cm (P < 0.001). The TC-specific mortalities and survivals were further investigated among more detailed subgroups divided by different tumor size, and a threshold of 3 cm could be observed (P < 0.005) for risk stratification.

Conclusions: Mortality risk increased with tumor size in PTC patients in stage IVB. Our findings demonstrated the possibility of further stratification in IVB stage in current TNM staging system. Patients with tumor size over 3 cm had an excessively high risk of PTC-specific mortality, which may justify the necessity of more aggressive treatment for them.

Prognostic Impact of Histologic Grade for Papillary Thyroid Carcinoma

BACKGROUND

While numerous factors affect prognosis in papillary thyroid carcinoma (PTC), the comparative impact of histologic grade has not been well described. Moreover, indications for external beam radiation therapy (EBRT) remain imprecise. We evaluate clinicopathologic characteristics and outcomes for PTC stratified by grade.

METHODS

We profiled histologic grade for PTC (well differentiated, moderately differentiated, poorly differentiated) via hospital (National Cancer Database) and population-based (Surveillance, Epidemiology, and End Results) registries. Cox regression was used to adjust for clinicopathologic covariates. Statistical interactions between subtypes and the effect of EBRT on survival were assessed.

RESULTS

Collectively, worsening clinicopathologic factors (age, tumor size, extrathyroidal extension, nodal spread, M1 disease) and outcomes (disease-free survival, overall survival) correlated with less differentiated state, across all histologic grades (p < 0.001). Multivariable analysis showed escalating hazard with loss of differentiation relative to well-differentiated PTC (moderately differentiated hazard ratio [HR] 1.21, 95% confidence interval [CI] 1.04-1.41, p = 0.02; poorly differentiated HR 2.62, 95% CI 2.23-3.08, p < 0.001). Correspondingly, greater survival benefit was associated with EBRT for poorly differentiated cases (HR 0.36, 95% CI 0.18-0.72, p = 0.004). This finding was upheld after landmark analysis to address potential immortal time bias (HR 0.37, 95% CI 0.17-0.80, p = 0.01).

CONCLUSIONS

Worsening histologic grade in PTC is independently associated with parallel escalation in mortality risk, on a scale approximating or surpassing established thyroid cancer risk factors. On preliminary analysis, EBRT was associated with improved survival in the most aggressive or least differentiated subvariants. Further investigation is warranted to examine the efficacy of EBRT for select poorly differentiated thyroid carcinomas.

Prevalence and Risk of Metastatic Thyroid Cancers and Management Outcomes: A National Perspective

OBJECTIVES

Examine the prevalence and risk of metastasis in thyroid cancers and management outcomes.

STUDY DESIGN

Retrospective analysis of the National Cancer Database, 2004-2014.

METHODS

The study population included adult (≥ 18 years) patients with thyroid cancer. Analysis included multivariate logistic regression and Cox hazard ratio modeling.

RESULTS

A total of 152,979 patients were included. Distant metastasis was reported in 1,867 (1.22%) patients. The distribution of metastatic cases based on pathology and tumor size were as follows in descending order: papillary thyroid carcinoma (PTC) 1 to 4 cm (30.53%), PTC > 4 cm (19.34%), undifferentiated (UTC) > 4 cm (14.14%), PTC < 1 cm (8.46%), follicular thyroid carcinoma (FTC) > 4 cm (7.28%), FTC 1 to 4 cm (5.52%), medullary thyroid cancer (MTC) ≤ 4 cm (3.96%), MTC > 4 cm (3.91%), UTC ≤ 4 cm (3.32%), Hürthle (HCC ) > 4 cm (2.09%), and HCC 1 to 4 cm (1.45%). Significant predictors of distant metastasis, while controlling for tumor pathology and size, included older age, male gender, non-White minorities, presence of multiple comorbidities, minimal, gross extrathyroidal extension (ETE), lymphovascular invasion (LVI), and concomitant central and lateral lymph node metastasis (LNM) (P < .05 each). The risk of distant metastasis in the absence of nodal metastasis, ETE, and LVI was highest for FTC > 4 cm.

CONCLUSION

Although the risk of metastasis in well-differentiated thyroid carcinoma (WDTC) is low, the prevalence of metastatic thyroid cancer is highest in WDTC population because it is the most common type of thyroid cancer. Certain pathological features, including minimal ETE and central LNM, are associated with a higher prevalence of metastatic disease.

LEVEL OF EVIDENCE

NA Laryngoscope, 131:237-244, 2021.

The Role of postoperative external beam radiotherapy for differentiated thyroid carcinoma: A Systematic review and meta-analysis

The indications for external beam radiotherapy (RT) in differentiated thyroid carcinomas (DTC) are still undefined. The objective of this study was to synthesize current evidence defining the role of postoperative RT in patients with DTC. A systematic review and meta-analysis were done. Included studies compared oncologic outcomes and toxicity of RT vs no RT in patients with DTC. Nine studies were included, two prospective and seven retrospective cohorts. RT improved 5-year locoregional recurrence-free survival but not overall survival and distant metastasis failure-free survival. The locoregional control benefit was seen in patients at increased risk for recurrence, including those with advanced age, locoregionally advanced disease, gross or microscopic residual tumor, and structural invasion. Serious RT-related acute and late toxicities were rare. Available evidence suggests that postoperative RT can improve locoregional control in high-risk DTC with acceptable toxicity. Further prospective studies are warranted.

Radioiodine-Refractory Thyroid Cancer: Molecular Basis of Redifferentiation Therapies, Management, and Novel Therapies

Recurrent, metastatic disease represents the most frequent cause of death for patients with thyroid cancer, and radioactive iodine (RAI) remains a mainstay of therapy for these patients. Unfortunately, many thyroid cancer patients have tumors that no longer trap iodine, and hence are refractory to RAI, heralding a poor prognosis. RAI-refractory (RAI-R) cancer cells result from the loss of thyroid differentiation features, such as iodide uptake and organification. This loss of differentiation features correlates with the degree of mitogen-activated protein kinase (MAPK) activation, which is higher in tumors with BRAF (B-Raf proto-oncogene) mutations than in those with RTK (receptor tyrosine kinase) or RAS (rat sarcoma) mutations. Hence, inhibition of the mitogen-activated protein kinase kinase-1 and -2 (MEK-1 and -2) downstream of RAF (rapidly accelerated fibrosarcoma) could sensitize RAI refractivity in thyroid cancer. However, a significant hurdle is the development of secondary tumor resistance (escape mechanisms) to these drugs through upregulation of tyrosine kinase receptors or another alternative signaling pathway. The sodium iodide symporter (NIS) is a plasma membrane glycoprotein, a member of solute carrier family 5A (SLC5A5), located on the basolateral surfaces of the thyroid follicular epithelial cells, which mediates active iodide transport into thyroid follicular cells. The mechanisms responsible for NIS loss of function in RAI-R thyroid cancer remains unclear. In a study of patients with recurrent thyroid cancer, expression levels of specific ribosomal machinery-namely PIGU (phosphatidylinositol glycan anchor biosynthesis class U), a subunit of the GPI (glycosylphosphatidylinositol transamidase complex-correlated with RAI avidity in radioiodine scanning, NIS levels, and biochemical response to RAI treatment. Here, we review the proposed mechanisms for RAI refractivity and the management of RAI-refractive metastatic, recurrent thyroid cancer. We also describe novel targeted systemic agents that are in use or under investigation for RAI-refractory disease, their mechanisms of action, and their adverse events.

10-Year Locoregional Control with Postoperative External Beam Radiotherapy in Patients with Locally Advanced High-Risk Non-Anaplastic Thyroid Carcinoma De Novo or at Relapse, a Propensity Score Analysis

(1) Background: To assess the role of postoperative external beam radiotherapy (pEBRT) on locoregional failure (LRF) for patients with locally advanced high-risk non-anaplastic thyroid carcinoma (naTC) at primary event or relapse. (2) Methods: Between 1995 and 2015, postoperative naTC patients with a theoretical indication for EBRT were included based on criteria that were common to American-British-French current guidelines, i.e., pT3-4, pN+, gross or microscopic residual disease. Inverse probability of treatment weighting (IPTW) after multiple imputation was used to reduce selection biases. (3) Results: Of 254 naTC patients, 216 patients underwent pEBRT (106 de novo, 110 at relapse, median dose 60 Gy) and 38 underwent surgery only. pEBRT patients had more gross residual disease, a major prognostic factor (p = 0.027) but less perineural invasion (p = 0.008) or lymphovascular emboli (p = 0.009). pEBRT patients more frequently underwent radioiodine therapy (p = 0.026). The 10-year cumulative incidence of LRF was 56% (95% CI, 32–74%) in operated patients, and 23% (95% CI, 17–30%) in pEBRT patients. After IPTW method, pEBRT reduced the risk of LRF (hazard ratio 0.30; 95% CI [0.18–0.49], p < 0.001), but had no impact on OS. In the pEBRT group, non-Intensity Modulated RadioTherapy (IMRT) plans and interruption of the radiotherapy were associated with poorer survival, while extended versus limited field strategy and dose were not. (4) Conclusions: In naTC patients who have pT3-4, pN+ disease or R1-2 resection, pEBRT improved LRF. Limited-field IMRT is preferred.

Targeting autophagy in thyroid cancers

Thyroid cancer is one of the most common endocrine malignancies. Although the prognosis for the majority of thyroid cancers is relatively good, patients with metastatic, radioiodine-refractory or anaplastic thyroid cancers have an unfavorable outcome. With the gradual understanding of the oncogenic events in thyroid cancers, molecularly targeted therapy using tyrosine kinase inhibitors (TKIs) is greatly changing the therapeutic landscape of radioiodine-refractory differentiated thyroid cancers (RR-DTCs), but intrinsic and acquired drug resistance, as well as adverse effects, may limit their clinical efficacy and use. In this setting, development of synergistic treatment options is of clinical significance, which may enhance the therapeutic effect of current TKIs and further overcome the resultant drug resistance. Autophagy is a critical cellular process involved not only in protecting cells and organisms from stressors but also in the maintenance and development of various kinds of cancers. Substantial studies have explored the complex role of autophagy in thyroid cancers. Specifically, autophagy plays important roles in mediating the drug resistance of small-molecular therapeutics, in regulating the dedifferentiation process of thyroid cancers and also in affecting the treatment outcome of radioiodine therapy. Exploring how autophagy intertwines in the development and dedifferentiation process of thyroid cancers is essential, which will enable a more profound understanding of the physiopathology of thyroid cancers. More importantly, these advances may fuel future development of autophagy-targeted therapeutic strategies for patients with thyroid cancers. Herein, we summarize the most recent evidence uncovering the role of autophagy in thyroid cancers and highlight future research perspectives in this regard.

Management of differentiated thyroid carcinomas

INTRODUCTION AND OBJECTIVES

Radioiodine is the principal treatment for differentiated thyroid carcinomas. The aim of this study is to present our experience in the management of these tumours.

MATERIAL AND METHOD

We present a retrospective study of 55 patients operated for differentiated thyroid carcinoma in our hospital between 2007 and 2011.

RESULTS

The mean age at time of diagnosis was 49 years, and females predominated (78% of cases). Seventy eight percent of the patients were in the initial stages (stages i and ii). The definitive histopathological diagnosis was papillary carcinoma in 84% and follicular carcinoma in the remaining 16%. All of the patients, with the exception of 2 (4%), underwent total thyroidectomy, with lymphadenectomy in 58% of cases. Nine percent of the patients had permanent hypoparathyroidism and although 18% suffered transitory unilateral paralysis, 40% of these female patients had completely recovered after 6 months. Eighty-nine percent of the patients were given radioiodine postoperatively. There was a recurrence rate of 40% most of which was at cervical level (29% of the patients). Survival at 5 years was 87%, 95% of the papillary subtype, falling to 56% of the follicular subtype (P=.001).

DISCUSSION/CONCLUSIONS

The prognosis for differentiated thyroid carcinomas is excellent after appropriate surgical treatment, thorough preoperative assessment,and strict postoperative follow-up due to the significant recurrence rates.