Active Surveillance of Papillary Thyroid Cancer: Frequency and Time Course of the Six Most Common Tumor Volume Kinetic Patterns.

Background: The change in size of the papillary thyroid cancer (PTC) nodule during active surveillance has traditionally been characterized as either stable, increasing, or decreasing based on changes in maximal tumor diameter or tumor volume. More recently, it has been observed that the changes in tumor size observed during observation are more complex with tumor volume kinetic patterns that can be characterized either as stable (Pattern I), early increase in volume (Pattern II), later increase in volume (Pattern III), early increase in volume followed by stability (Pattern IV), stability followed by an increase in volume (Pattern V), or a decrease in tumor volume (Pattern VI). Methods: The frequency, time course, and clinical correlates of these six tumor volume kinetic patterns were analyzed in a cohort of 483 patients with low-risk PTC up to 1.5 cm in maximal diameter followed with active surveillance at our center for a median of 3.7 years. Results: The cumulative incidence of an increase in tumor volume for the entire cohort was 15.9% [confidence interval (CI) 11.8-20.0] at 5 years. At 5 years, most tumors demonstrated stability (78.8%, Pattern I) with 10.0% showing early growth (Pattern II), 4.1% late growth (Pattern III), 1.9% growth then stability (Pattern IV), 0.6% stability then growth (Pattern V), and 5.6% with a decrease in tumor volume (Pattern VI). Tumor volume doubling time during exponential growth significantly differed across the kinetic patterns, with median values of 2.4, 7.1, and 3.3 years for Patterns II, III, and IV, respectively (p < 0.01). Similarly, the time to a change in tumor volume was significantly different across the kinetic patterns, with median values of 1.5, 3, 1.6, 4.7, and 4.1 years for Patterns II, III, IV, V, and VI, respectively (analysis of variance, p < 0.01). Clinical correlates at baseline were not associated with tumor volume kinetic pattern. Conclusions: These six kinetic tumor volume patterns provide a comprehensive description of the changes in PTC tumor volume observed during the first 5 years of active surveillance.

Enhancing Radioiodine Incorporation in BRAF-Mutant, Radioiodine-Refractory Thyroid Cancers with Vemurafenib and the Anti-ErbB3 Monoclonal Antibody CDX-3379: Results of a Pilot Clinical Trial.

Background: Oncogenic activation of mitogen-activated protein kinase (MAPK) signaling is associated with radioiodine refractory (RAIR) thyroid cancer. Preclinical models suggest that activation of the receptor tyrosine kinase erbB-3 (HER3) mitigates the MAPK pathway inhibition achieved by BRAF inhibitors in BRAFV600E mutant thyroid cancers. We hypothesized that combined inhibition of BRAF and HER3 using vemurafenib and the human monoclonal antibody CDX-3379, respectively, would potently inhibit MAPK activation and restore radioactive iodine (RAI) avidity in patients with BRAF-mutant RAIR thyroid cancer. Methods: Patients with BRAFV600E RAIR thyroid cancer were evaluated by thyrogen-stimulated iodine-124 (124I) positron emission tomography-computed tomography (PET/CT) at baseline and after 5 weeks of treatment with oral vemurafenib 960 mg twice daily alone for 1 week, followed by vemurafenib in combination with 1000 mg of intravenous CDX-3379 every 2 weeks. Patients with adequate 124I uptake on the second PET/CT then received therapeutic radioactive iodine (131I) with vemurafenb+CDX-3379. All therapy was discontinued two days later. Treatment response was monitored by serum thyroglobulin measurements and imaging. The primary endpoints were safety and tolerability of vemurafenib+CDX-3379, as well as the proportion of patients after vemurafenb+CDX-3379 therapy with enhanced RAI incorporation warranting therapeutic 131I. Results: Seven patients were enrolled; six were evaluable for the primary endpoints. No grade 3 or 4 toxicities related to CDX-3379 were observed. Five patients had increased RAI uptake after treatment; in 4 patients this increased uptake warranted therapeutic 131I. At 6 months, 2 patients achieved partial response after 131I and 2 progression of disease. Next-generation sequencing of 5 patients showed that all had co-occurring telomerase reverse transcriptase promoter alterations. A deleterious mutation in the SWItch/Sucrose Non-Fermentable (SWI/SNF) gene ARID2 was discovered in the patient without enhanced RAI avidity after therapy and an RAI-resistant tumor from another patient that was sampled off-study. Conclusions: The endpoints for success were met, providing preliminary evidence of vemurafenib+CDX-3379 safety and efficacy for enhancing RAI uptake. Preclinical data and genomic profiling in this small cohort suggest SWI/SNF gene mutations should be investigated as potential markers of resistance to redifferentiation strategies. Further evaluation of vemurafenib+CDX-3379 as a redifferentiation therapy in a larger trial is warranted (ClinicalTrials.gov: NCT02456701).

Intensity-modulated radiation therapy and doxorubicin in thyroid cancer: A prospective phase 2 trial.

BACKGROUND: The use of external-beam radiotherapy for locally advanced nonanaplastic thyroid cancer remains controversial. This prospective study evaluated the efficacy and tolerability of intensity-modulated radiation therapy (IMRT) with or without concurrent chemotherapy in patients with locally advanced thyroid cancer. METHODS: The authors conducted a nonrandomized phase 2 trial of IMRT with or without concurrent doxorubicin in patients with gross residual or unresectable nonanaplastic thyroid carcinoma (ClinicalTrials.gov identifier NCT01882816). The primary end point was 2-year locoregional progression-free survival (PFS). Secondary end points included overall survival (OS), safety, patient-reported outcomes, and functional outcomes. RESULTS: Twenty-seven patients were enrolled: 12 (44.4%) with unresectable disease and 15 (55.6%) with gross residual disease. The median follow-up was 45.6 months (interquartile range, 42.0-51.6 months); the 2-year cumulative incidences of locoregional PFS and OS were 79.7% and 77.3%, respectively. The rate of grade 3 or higher acute and late toxicities was 33.4%. There were no significant functional differences 12 months after treatment (assessed objectively by the modified barium swallow study). Patient-reported quality of life in the experimental group was initially lower but returned to the baseline after 6 months and improved thereafter. In a post hoc analysis, concurrent chemotherapy with intensity-modulated radiation therapy (CC-IMRT) resulted in significantly less locoregional failure at 2 years (no failure vs 50%; P = .001), with higher rates of grade 2 or higher acute dermatitis, mucositis, and dysphagia but no difference in long-term toxicity, functionality, or patient-reported quality of life. CONCLUSIONS: In light of the excellent locoregional control rates achieved with CC-IMRT and its acceptable toxicity profile as confirmed by functional assessments and patient-reported outcomes, CC-IMRT may be preferred over IMRT alone.

Thyroid Cancer and Telemedicine During the COVID-19 Pandemic.

The COVID-19 pandemic has forced endocrinologists to utilize telemedicine to care for their patients. There is limited information on the experience of endocrinologists in managing patients with thyroid cancer virtually. We sent a 9-item questionnaire to endocrinologists and endocrine surgeons at our institution to better understand the barriers and benefits of caring for patients with thyroid cancer via telemedicine, as well as how we can incorporate telemedicine into our future care of patients with this malignancy. Among the 9 physicians who responded, the majority listed technological issues with the virtual platform as a challenge in caring for patients with thyroid cancer remotely. Additional barriers included difficulty in expressing empathy, decreased ability to coordinate care with the interdisciplinary team, and lack of the physical examination. Benefits included compliance with social distancing measures and convenience for patients with American Thyroid Association (ATA) low-risk thyroid cancer who presented for follow-up visits. Overall, physicians were satisfied or strongly satisfied with caring for patients with thyroid cancer remotely, especially low-risk patients on long-term follow-up. That said, they recommend that some patients be seen in person after the pandemic, including symptomatic patients and ATA high-risk patients. While the COVID-19 pandemic has allowed endocrinologists to manage patients with thyroid cancer remotely, the providers have faced challenges, some of which can be improved upon. Further studies will help determine how telemedicine affects patient outcomes, including satisfaction, disease progression, and survival, which will inform how we may incorporate this practice into our future care of patients with thyroid cancer.

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.

Thyroid Cancer Bone Metastasis: Survival and Genomic Characteristics of a Large Tertiary Care Cohort.

Bone metastasis (BM) in differentiated thyroid cancer (DTC) is the second most common site of metastasis after lung. Bone metastases are associated with worse prognosis in DTC. In this study, we examined risk factors for overall survival in patients with BM and for the first time explore the pattern of genomic alterations in DTC BM. PATIENTS AND METHODS: A Health Insurance Portability and Accountability Act (HIPAA) compliant, institutional review board-approved retrospective evaluation of the medical record was performed for all patients treated at a single institution for thyroid cancer over a 16-year period. Seventy-four patients met inclusion criteria. Multiple prognostic factors including age, sex, genes, radioactive iodine, and radiation or kinase inhibitor therapies were analyzed. Univariate and multivariate analyses were performed. RESULTS: Treatment with external beam radiation was found to significantly increase survival (P = 0.03). The 5-year survival rate was 59% and median survival was 92 months. Patients who developed bone metastasis earlier tend to live longer (P = 0.06). The presence of TERT and BRAF mutations did not significantly worsen the prognosis (P = 0.10). CONCLUSION: Patients with DTC can benefit from early treatment with external beam radiation therapy, especially those who develop bone metastasis within 3 years of primary TC diagnosis. Kinase inhibitor treatment tended to prolong survival but not in a statistically significant manner. Sex, age, and TERT or BRAF genetic mutations did not significantly affect the prognosis.

Thyroid Cancer Brain Metastasis: Survival and Genomic Characteristics of a Large Tertiary Care Cohort.

PURPOSE: Brain metastases (BMs) in patients with differentiated thyroid cancer (DTC) are rare but associated with poor prognosis. We examined risk factors for overall survival (OS) in this population and explored the pattern of genomic alterations. METHODS: Single-institution, retrospective review of all patients with DTC from January 2000 to November 2016 identified 79 patients for analysis. Multiple prognostic factors, including age, gender, distal metastasis (DM), diagnosis time, DM sites, BM diagnosis time, BM number and size, genomic sequencing data, craniectomy, external beam radiation therapy, and kinase inhibitor therapies, were evaluated. Univariate and multivariate analyses were performed. RESULTS: Median survival after BM was 18 months. One- and 3-year survival rates were 63% and 33%, respectively. Univariate analysis identified 4 covariates correlated with prolonged survival: time between DTC diagnosis and BM for less than 3 years (P = 0.01), time from initial DM diagnosis to BM for 22 months or less (P = 0.03), 3 BM sites or fewer (P = 0.002), and craniectomy (P = 0.05). Multivariate model revealed 3 variables associated with OS: DTC diagnosis to BM time of less than 3 years (P = 0.04), craniectomy (P = 0.06), and patients with fewer than 3 BM sites (P = 0.06). The majority of patients with BM had a telomerase reverse transcriptase promoter mutation, However, mutational status was not an independent predictor of survival. CONCLUSIONS: For BM from DTC, time interval between DTC diagnosis and BM, number of BM sites, and craniectomy were independently associated with OS. Further studies are needed to define the role of genomic mutations in advanced cancer.

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.

PURPOSE: To assess molecular targeted therapy (MTT)'s ability to affect tumour volume doubling time (TVDT) and disease-specific survival (DSS) in patients presenting with lung metastasis from radioactive iodine refractory progressive thyroid cancer. METHODS: In this retrospective study, we examined the clinical characteristics, average tumour volume doubling times of lung metastasis and disease-specific survival of patients with lung metastasis from differentiated thyroid cancer who were treated with MTT. RESULTS: The 5-year DSS from the distant metastasis (DM) diagnosis was 72% with median survival of 8 years (95% CI: 6.6-9.5). The median survival was 2.9 years after MTT start (95% CI: 2.1-3.6). On MTT, lung average tumour volume doubling time (midDT) was prolonged to midDT ≥3 years in 75% of patients with baseline midDT ≤1 year and 100% of patients with midDT 1-3 years. In patients with rapidly progressive thyroid cancer (midDT ≤1 year at baseline), the median survival was 4.5 years in those with MTT-achieved midDT ≥3 years (95% CI: 2.9-6.2), as opposed to 2.3 years (95% CI: 0.3-4.3) and 0.7 years (95% CI: 0.2-1.3) in those with MTT-achieved midDT of 1-3 years and MTT-achieved midDT ≤1 year, respectively (log rank P < 0.001). CONCLUSION: Lung midDT is a useful and important clinical marker of disease-specific survival for patients with progressive radioactive iodine refractory (RAIR) metastatic thyroid cancer. In patients with rapidly progressive metastatic RAIR thyroid cancer, molecular targeted therapy prolongs lung tumour volume doubling time and is associated with improved disease-specific survival.

Vemurafenib Redifferentiation of BRAF Mutant, RAI-Refractory Thyroid Cancers.

CONTEXT: BRAFV600E mutant thyroid cancers are often refractory to radioiodine (RAI). OBJECTIVES: To investigate the utility and molecular underpinnings of enhancing lesional iodide uptake with the BRAF inhibitor vemurafenib in patients with RAI-refractory (RAIR). DESIGN: This was a pilot trial that enrolled from June 2014 to January 2016. SETTING: Academic cancer center. PATIENTS: Patients with RAIR, BRAF mutant thyroid cancer. INTERVENTION: Patients underwent thyrotropin-stimulated iodine-124 (124I) positron emission tomography scans before and after ~4 weeks of vemurafenib. Those with increased RAI concentration exceeding a predefined lesional dosimetry threshold (124I responders) were treated with iodine-131 (131I). Response was evaluated with imaging and serum thyroglobulin. Three patients underwent research biopsies to evaluate the impact of vemurafenib on mitogen-activated protein kinase (MAPK) signaling and thyroid differentiation. MAIN OUTCOME MEASURE: The proportion of patients in whom vemurafenib increased RAI incorporation to warrant 131I. RESULTS: Twelve BRAF mutant patients were enrolled; 10 were evaluable. Four patients were 124I responders on vemurafenib and treated with 131I, resulting in tumor regressions at 6 months. Analysis of research tumor biopsies demonstrated that vemurafenib inhibition of the MAPK pathway was associated with increased thyroid gene expression and RAI uptake. The mean pretreatment serum thyroglobulin value was higher among 124I responders than among nonresponders (30.6 vs 1.0 ng/mL; P = 0.0048). CONCLUSIONS: Vemurafenib restores RAI uptake and efficacy in a subset of BRAF mutant RAIR patients, probably by upregulating thyroid-specific gene expression via MAPK pathway inhibition. Higher baseline thyroglobulin values among responders suggest that tumor differentiation status may be a predictor of vemurafenib benefit.

Intensity-Modulated Radiation Therapy With or Without Concurrent Chemotherapy in Nonanaplastic Thyroid Cancer with Unresectable or Gross Residual Disease.

BACKGROUND: Differentiated thyroid cancer typically has an indolent clinical course but can cause significant morbidity by local progression. Oncologic surgical resection can be technically difficult due to the proximity to critical normal structures in the neck. Our objective was to review the safety, feasibility, and outcomes of definitive-intent intensity-modulated radiation therapy (IMRT) and to analyze whether patients receiving concurrent chemotherapy (CC-IMRT) had higher rates of disease control and survival over IMRT alone in patients with unresectable or gross residual disease (GRD). METHODS: Eighty-eight patients with GRD or unresectable nonanaplastic, nonmedullary thyroid cancer treated with definitive-intent IMRT between 2000 and 2015 were identified. Local progression-free survival (LPFS), distant metastasis-free survival (DMFS), and overall survival (OS) were evaluated using the Kaplan-Meier method. Univariate and multivariate analyses using cox regression were used to determine the impact of clinical conditions and treatment on LPFS, DMFS, and OS. RESULTS: Of the 88 patients identified, 45 (51.1%) were treated CC-IMRT and 43 (48.9%) were treated with IMRT alone. All patients treated with CC-IMRT received weekly doxorubicin (10 mg/m2). The median follow-up among surviving patients was 40.3 months and 29.2 months for all patients. The LPFS at 4 years was 77.3%. Patients receiving CC-IMRT had higher LPFS compared with IMRT alone (CC-IMRT 85.8% vs. IMRT 68.8%, p = 0.036). The 4-year OS was 56.3% for all patients. Patients treated with CC-IMRT had higher OS compared to patients treated with IMRT alone (CC-IMRT 68.0% vs. IMRT 47.0%, p = 0.043). On multivariate analysis, receipt of concurrent chemotherapy was associated with a lower risk of death (HR 0.395, p = 0.019) and lower risk of local failure (HR 0.306, p = 0.042). Grade 3+ acute toxicities occurred in 23.9% of patients, the most frequent being dermatitis (18.2%) and mucositis (9.1%). 17.1% of patients required a percutaneous endoscopic gastrostomy (PEG) tube during or shortly after completion of RT, with 10.1% of patients needing a PEG more than 12 months after therapy. The rates of acute and late toxicities were not statistically higher in the CC-IMRT cohort, although trends towards higher toxicity in the CC-IMRT were present for dermatitis and PEG requirement. CONCLUSIONS: IMRT is a safe and effective means to achieve local control in patients with unresectable or incompletely resected nonanaplastic, nonmedullary thyroid cancer. Concurrent doxorubicin was not associated with worse toxicity and should be considered in these patients given its potential to improve local control and overall survival.

AHNS Series: Do you know your guidelines? AHNS Endocrine Section Consensus Statement: State-of-the-art thyroid surgical recommendations in the era of noninvasive follicular thyroid neoplasm with papillary-like nuclear features.

The newly introduced pathologic diagnosis of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) will result in less bilateral thyroid surgery as well as deescalation in T4 suppressive and radioactive iodine treatment. Although, NIFTP is a nonmalignant lesion that has nuclear features of some papillary malignancies, the challenge for the surgeon is to identify a lesion as possibly NIFTP before the pathologic diagnosis. NIFTP, due to its reduction of overall rates of malignancy, will result in the initial surgical pendulum swinging toward lobectomy instead of initial total thyroidectomy. This American Head and Neck Society endocrine section consensus statement is intended to inform preoperative evaluation to attempt to identify those patients whose final pathology report may ultimately harbor NIFTP and can be offered a conservative surgical plan to assist in cost-effective, optimal management of patients with NIFTP.

Novel concepts for initiating multitargeted kinase inhibitors in radioactive iodine refractory differentiated thyroid cancer.

Multitargeted kinase inhibitors have been shown to improve progression-free survival in patients with structurally progressive, radioactive iodine refractory differentiated thyroid cancer. While the inclusion criteria for phase 3 clinical trials and clinical practice guidelines provide guidance with regard to the minimal requirements that need to be met prior to initiation of a multitargeted kinase inhibitor, a better way to integrate the rate of structural disease progression with the size of the metastatic foci to more precisely define the optimal time to recommend initiation of therapy for individual patients is needed. In this manuscript we describe how to use assessments of tumor size and growth rates (structural disease doubling times) to define the critical point in time when the volume and rate of progression of metastatic structural disease merits consideration for initiation of systemic therapy (the inflection point).

Natural History and Tumor Volume Kinetics of Papillary Thyroid Cancers During Active Surveillance.

Importance: Active surveillance of low-risk papillary thyroid cancer (PTC) is now an accepted alternative to immediate surgery, but experience with this approach outside of Japan is limited. The kinetics (probability, rate, and magnitude) of PTC tumor growth under active surveillance have not been well defined. Objective: To describe the kinetics of PTC tumor growth during active surveillance. Design, Setting, and Participants: Cohort study of 291 patients undergoing active surveillance for low-risk PTC (intrathyroidal tumors ≤1.5 cm) with serial tumor measurements via ultrasonography at a tertiary referral center in the United States. Intervention: Active surveillance. Main Outcomes and Measures: The cumulative incidence, rate, and magnitude of the change in tumor diameter or volume, as well as associations with patient and tumor characteristics. Results: Of the 291 patients, 219 (75.3%) were women; mean (SD) age was 52 (15) years. During a median (range) active surveillance of 25 (6-166) months, growth in tumor diameter of 3 mm or more was observed in 11 of 291 (3.8%) patients, with a cumulative incidence of 2.5% (2 years) and 12.1% (5 years). No regional or distant metastases developed during active surveillance. In all cases, 3-dimensional measurements of tumor volume allowed for earlier identification of growth (median, 8.2 months; range, 3-46 months before increase in tumor diameter). In multivariable analysis, both younger age at diagnosis (hazard ratio per year, 0.92; 95% CI, 0.87-0.98; P = .006) and risk category at presentation (hazard ratio for inappropriate, 55.17; 95% CI, 9.4-323.19; P < .001) were independently associated with the likelihood of tumor growth. Of the tumors experiencing volume growth, kinetics demonstrated a classic exponential growth pattern, with a median doubling time of 2.2 years (range, 0.5-4.8 years; median r2 = 0.75; range, 0.42-0.99). Conclusions and Relevance: The rates of tumor growth during active surveillance in a US cohort with PTCs measuring 1.5 cm or less were low. Serial measurement of tumor volumes may facilitate early identification of tumors that will continue to grow and thereby inform the timing of surveillance imaging and therapeutic interventions.

VARIABILITY IN THYROID CANCER MANAGEMENT AND PROGNOSIS AMONG HISPANIC VERSUS NON-HISPANIC PATIENTS : 17 YEARS DATA FROM UNIVERSITY OF TEXAS HEALTH SCIENCE CENTER AND UNIVERSITY HEALTH SYSTEM AT SAN ANTONIO.

Abstracts: Objective : Given the increase in the incidence of thyroid cancer in the United States, and it's potential public health implications, patient studies assessing ethnic, disparity and health care access are important. In this study, we retrospectively examined the variability in stage of thyroid cancer at presentation and final outcome among Hispanic vs non-Hispanic patients. METHOD: After obtaining IRB approval, we retrospectively reviewed the medical records of 220 adult patients with papillary thyroid carcinoma(PTC) who were treated at UT Health Science Center San Antonio between1996 and 2013. At disease presentation, patients were staged and risk stratified according to the 2009 American Thyroid Association (ATA) and TNM staging system. Clinical data obtained during the first 6-18 months was used to identify the initial response to therapy and clinical data from the last follow up visit was used to identify the "final" outcome. We examined the effect of insurance and ethnicity on initial response to therapy and final outcome using Chi-square test and one way ANOVA. RESULT: Our patient population's ATA risk at diagnosis, initial response to therapy and final outcome did not differ by ethnicity (P=0.5, 0.3 &0.4) and insurance coverage(P=0.7, 0.3 & 0.4) . CONCLUSION: Insurance coverage and ethnicity may not be independent factors since ethnic minority individuals are more likely to be uninsured.

Patients with Multifocal Macroscopic Papillary Thyroid Carcinoma Have a Low Risk of Recurrence at Early Follow-Up after Total Thyroidectomy and Radioactive Iodine Treatment.

BACKGROUND: Multifocal thyroid cancer involvement is a common presentation in papillary thyroid cancer. The risk of recurrence of intrathyroidal multifocal papillary microcarcinoma (<1 cm) is documented to be low. However, the risk of recurrence of multifocal macroscopic thyroid cancer is not known. Prior studies have suggested that both the number of foci and the presence of nodal involvement at diagnosis are important predictors of recurrence in multifocal papillary thyroid carcinoma (PTC). OBJECTIVES: In this retrospective review of 99 patients presenting with multifocal macroscopic PTC (with 2 tumor foci >1 cm) without gross extrathyroidal extension, we examined the clinical outcomes of patients in the first 2 years after the initial therapy and at the end of the follow-up period (median: 5 years). RESULTS: Half of the patients presenting with multifocal macroscopic PTC had nodal involvement at diagnosis. Only 4 patients had a recurrence on long-term follow-up, all with classic or tall-cell variant PTC with bulky nodal involvement at diagnosis. The number of tumor foci did not influence the risk of recurrence in this cohort. The median time to recurrence in these 4 patients was 11 years, with all patients having a recurrence after 9 years of follow-up. None of patients developed distant metastasis or died from thyroid cancer. CONCLUSIONS: Patients presenting with multifocal macroscopic papillary thyroid cancer without bulky nodal involvement or gross extrathyroidal extension have a low risk of thyroid cancer recurrence.

Tumor volume doubling time of pulmonary metastases predicts overall survival and can guide the initiation of multikinase inhibitor therapy in patients with metastatic, follicular cell-derived thyroid carcinoma.

BACKGROUND: The current study was conducted to better characterize the association between overall survival (OS) from metastatic thyroid cancer and the rate of structural disease progression. METHODS: In this retrospective study, the average tumor volume doubling time (midDT) of 2 dominant lung metastases was used to group patients into 6 clinically relevant cohorts. OS was calculated from the time of metastasis diagnosis and from the time the pulmonary lesions crossed over the 1-cm diameter threshold. RESULTS: The tumor growth rate was remarkably constant in lung metastases from thyroid cancer over a median follow-up of 8.5 years (median correlation coefficient, 0.92; coefficient of determination, 0.85). Patients with a midDT ≤1 year were found to have worse OS compared with those with a higher midDT (log-rank P = .01). The 5-year OS rate from the 1-cm diameter time point was 20% for patients with a midDT ≤1 year (15 patients), 50% for patients with a midDT of 1 to 2 years (19 patients), 53% for patients with a midDT of 2 to 3 years (9 patients), 80% for patients with a midDT of 3 to 4 years (6 patients), and 80% for patients with a midDT of ≥4 years or who were negative (12 patients). Within the group of patients with a midDT ≤1 year, the 2-year OS rate from the 1-cm diameter point was 88% in the patients treated with multikinase inhibitors (8 patients) versus 43% in the nontreated group (7 patients) (P = .13). CONCLUSIONS: The midDT of lung metastases appears to be a good prognostic indicator of OS in patients with metastatic thyroid cancer. Unlike the thyroglobulin DT, the midDT alone can be used to predict eligibility for multikinase inhibitor therapy. Cancer 2017;123:2955-64. © 2017 American Cancer Society.

Primary Thyroid Carcinoma with Low-Risk Histology and Distant Metastases: Clinicopathologic and Molecular Characteristics.

BACKGROUND: Distant metastases (DM) are a rare occurrence in well-differentiated thyroid carcinoma. The aim of this study was to analyze the clinical, pathologic, and molecular features of primary thyroid carcinoma with low-risk histology that develop DM. METHODS: A detailed clinicopathologic review and targeted next-generation sequencing were performed on a cohort of well-differentiated thyroid carcinoma lacking gross extrathyroidal extension, extensive vascular invasion, or significant lymph node metastases but exhibiting DM. RESULTS: Primary well-differentiated thyroid carcinoma with low-risk histologic features and DM was a rare occurrence, accounting for only 3% of metastatic non-anaplastic thyroid carcinoma. All 15 cases meeting the inclusion criteria harbored DM at presentation. The majority (11/15) of these tumors were follicular variant of papillary thyroid carcinoma (PTC), especially the encapsulated form (n = 8). The remaining patients harbored encapsulated Hürthle cell carcinoma (n = 2), encapsulated follicular carcinoma (n = 1), and an encapsulated papillary carcinoma classical variant (n = 1). Of the 12 encapsulated carcinomas, 10 had capsular invasion only and no vascular invasion. Ninety-two percent of the tumors exhibited extensive intra-tumoral fibrosis. Among the eight tumors that were subjected to next-generation sequencing analysis, a RAS mutation was the main driver (5/8), and TERT promoter mutation was highly prevalent (6/8). In four cases, TERT promoter mutations were associated with RAS or BRAF mutations. BRAF-mutated classical variant of papillary carcinoma also presented with DM but was less common (1/8). In 11/15 cases, the clinician was able to diagnose distant disease based on the clinical presentation. In 3/4 incidental cases that were genotyped, TERT promoter mutations were found. CONCLUSIONS: When DM occur in primary thyroid carcinoma with low-risk histology, they are almost always found at presentation. The majority are encapsulated follicular variant of PTC with capsular invasion only. TERT promoter mutations occur at a higher rate than that seen in PTC in general and may help explain the aggressive behavior of these histologically deceptive primary carcinomas.

Clinicopathologic Features of Fatal Non-Anaplastic Follicular Cell-Derived Thyroid Carcinomas.

BACKGROUND: The vast majority of thyroid cancers, in particular the non-anaplastic follicular cell-derived thyroid carcinomas (non-ANA FCDC), are considered indolent tumors with very low mortality. Hence, it is crucial to analyze the subgroup of these patients who die of disease (DOD) in order to identify clinicopathologic features predictive of disease-specific mortality. METHODS: All non-ANA FCDC operated at a tertiary cancer center between 1985 and 2010 who were DOD were identified and submitted to a meticulous clinicopathologic analysis. RESULTS: Out of 3750 non-ANA FCDC, 58 (1.5%) DOD cases were identified. The DOD group was composed of 33 (57%) poorly differentiated carcinomas (PDTC), 14 (24%) tall-cell variant papillary thyroid carcinomas (TCVPTC), four (7%) Hürthle cell carcinomas, three (5%) papillary microcarcinomas, two (3%) classical variant PTC, and two (3%) follicular variant PTC. Twenty-seven (47%) patients presented with distant metastases (DM), 28 (48%) developed DM during follow-up, while the remaining three (5%) had locally advanced non-resectable recurrence. Gross extension beyond the thyroid (GET) was present in 36 (62%) and extensive vascular invasion (VI) in 21 (36%) of cases. All microcarcinomas had PDTC in their clinically apparent cervical lymph nodes at presentation. Encapsulated thyroid carcinomas were responsible for 17% of DOD cases, and all had extensive VI and/or DM at presentation. All patients had at least one of these high-risk features at diagnosis: DM at presentation, PDTC, GET, and/or extensive VI. The majority of patients died from DM (n = 51; 88%), three (5%) from locoregional disease, three (5%) from both, and one (2%) from unknown cause. CONCLUSIONS: PDTC and TCVPTC are responsible for the vast majority of deaths in differentiated thyroid carcinomas, while the few fatal classical, follicular variant PTC and microcarcinomas all harbor a PDTC component, DM, or GET. Encapsulated differentiated thyroid carcinoma with focal capsular and/or VI without DM at presentation does not seem to cause death. Lack of DM at presentation, PDTC, GET, and extensive VI identify thyroid carcinomas that are at almost no risk of DOD. The vast majority of patients die of DM rather than locoregional invasion, prompting the need for effective systemic treatment.