Poorly differentiated carcinomas of the thyroid with trabecular, insular, and solid patterns: a clinicopathologic study of 183 patients

Characteristics and Prognostic Markers of Aggressive Subtypes of Thyroid Cancer: A Retrospective Study

OBJECTIVE

The prevalence of thyroid cancer has increased significantly. Aggressive subtypes of papillary thyroid cancer (AG-PTC) and high-grade follicular cell-derived malignancies (HGFM) are malignancies that lie between well-differentiated and undifferentiated cancers, and their management needs to be clarified. The aim of our study is to describe the clinicopathological characteristics of AG-PTC and HGFM and to assess their prognostic value.

METHODS

This was a retrospective chart review study at single center of patients with AG-PTC or HGFM. HGFM comprised of patients with poorly differentiated thyroid cancer (PDTC) and differentiated high-grade thyroid carcinoma. The clinical presentation, pathological characteristics, molecular markers, specific treatments, and clinical outcomes were compared between the groups.

RESULTS

Of the 3244 thyroid cancer charts reviewed, 136 met the criteria for AG-PTC and HGFM. The mean age at diagnosis was 49 years, with a predominance of women. The median follow-up duration was 3 years. The rate of persistent or recurrent disease was 40.3% in the AG-PTC group and 29.3% in the HGFM group, 4.5% died in the AG-PTC group, and 1.8% died in the HGFM group. The presence of vascular, lymphovascular invasion and extrathyroidal extension were associated with a higher incidence of persistent or recurrent disease (Hazard ratio: 2.5, 3.8, and 4.2, respectively; p < 0.05). When the Ki-67 index was divided into five groups, the recurrence rate was higher in the ≥ 20% Ki-67 group.

CONCLUSIONS

Possible prognostic markers for predicting worse prognosis include vascular/lymphovascular invasion, extrathyroidal extension, and the proliferative index Ki-67.

Isolated metastasis of the bowel from undifferentiated thyroid carcinoma. A case report and a literature review

In this article, we aim to demonstrate that thyroid carcinoma can metastasize to the small bowel. This case report involves a 66-year-old woman who underwent total thyroidectomy surgery in 2019, with histopathology revealing a 3A undifferentiated thyroid cancer. She presented with symptoms of bowel obstruction, including abdominal pain, nausea, and vomiting. Thyroid carcinoma accounts for less than 4% of all malignant neoplasms, making it the most common endocrine malignancy. The predominant type is papillary carcinoma, which generally has a favorable prognosis. In contrast, poorly differentiated thyroid cancers have a poor prognosis, with a 5-year postoperative survival rate of 66%. Common metastatic sites include the lungs, brain, and bones, with rare occurrences in organs such as the kidneys, spleen, adrenal glands, and ovaries. Intestinal metastases are extremely rare, with fewer than 15 cases of gastrointestinal localization documented in the literature. This case highlights the rare possibility of thyroid carcinoma metastasizing to the small bowel, emphasizing the need for clinicians to consider metastatic spread in patients with a history of thyroid cancer who present with gastrointestinal symptoms.

Clinicopathologic and Molecular Analysis of 15 Pediatric and Young Adult Patients with High-Grade Non-anaplastic Thyroid Carcinoma

High-grade follicular cell-derived non-anaplastic thyroid carcinomas are uncommon and typically diagnosed in the sixth to seventh decade of life. These tumors are rare in the pediatric (≤ 18 years old) and young adult (19-21 years old) populations. The molecular landscape of pediatric and young adult thyroid neoplasia has been suggested to be enriched in DICER1 gene alterations. Our intent was to evaluate pediatric and young adult high-grade follicular cell-derived non-anaplastic thyroid carcinomas for driver mutations. Thyroid carcinomas involving individuals under the age of 21 years were retrieved from our institutional archives. The patient population included 13 females and 2 males aged 9-20 years. Six patients were aged 9-16 years and nine patients were aged 19-20 years. The carcinomas were classified as poorly differentiated thyroid carcinoma (PDTC) (n = 6) and differentiated high-grade thyroid carcinoma (DHGTC) (n = 9). Two were poorly differentiated oncocytic thyroid carcinomas, and two were poorly differentiated follicular thyroid carcinomas. A well-differentiated component was not identified in 2 PDTCs. The DHGTCs were subclassified as follicular thyroid carcinoma (n = 4), classic subtype papillary thyroid carcinoma (n = 4), and oncocytic thyroid carcinoma (n = 1). Molecular evaluation revealed one differentiated high-grade follicular thyroid carcinoma, two poorly differentiated follicular thyroid carcinomas, and two PDTCs with DICER1 gene alterations. A DICER1-altered PDTC, DICER1-altered poorly differentiated follicular thyroid carcinoma, and a poorly differentiated oncocytic thyroid carcinoma had TP53 gene alterations. BRAF V600E immunohistochemistry (IHC) was positive in two cases. PanTRK IHC was positive in two cases, one of which had a confirmed SQSTM1::NTRK3 gene fusion. Immunohistochemistry for PTEN showed loss of expression in two tumors, one of which had a loss of function PTEN germline alteration. Clinical follow-up was available for 14 patients (range 24-347 months, median 101 months). Four patients had local/regional recurrences, and one patient had distant recurrences (bones and liver). At last, follow-up 10 patients were alive with no evidence of disease, 1 was alive with disease, 1 was alive with an unknown status, 1 died of disease, and 1 died of unknown causes. In summary, we report 15 additional cases of pediatric and young adult high-grade follicular cell-derived non-anaplastic thyroid carcinoma, with a subset harboring DICER1 (n = 5), NTRK (n = 2), and PTEN (n = 2) gene alterations. In this limited case series, two patients were dead at the last follow-up. Whether these findings are consistent within this patient population remains to be addressed as more patient series are published.

[18F]TFB PET/CT misses intense [124I]iodine-avid metastases after redifferentiation therapy in metastatic thyroid cancer

BACKGROUND

Fluorine 18-labelled tetrafluoroborate ([18F]TFB) is a substrate for the sodium/iodide symporter. In thyroid cancer, [18F]TFB-PET/CT may be an alternative to iodine imaging to evaluate the extent of disease, eligibility for radioiodine treatment, and success of redifferentiation therapies. We report the results of a pilot study to determine tumor uptake of [18F]TFB and compare its properties to [124I]IodinePET/CT in patients with metastatic thyroid cancer.

METHODS

Five patients were included in a prospective study. All patients received PET/CT 1 h after injection of 356 ± 12 MBq [18F]TFB and were given 230 ± 9 MBq [124I]Iodine orally on the same day, followed by PET/CT after 48 h. Before redifferentiation therapy, patients underwent an additional baseline [124I]Iodine PET/CT. Cases were analyzed by two board-certified specialists. Detection rates and Spearman correlation for [18F]TFB and [124I]Iodine were calculated.

RESULTS

Three patients had poorly differentiated thyroid cancer and received trametinib in a redifferentiation trial. Two patients had papillary thyroid cancer and did not receive redifferentiation therapy. Of the 33 lesions seen before/without redifferentiation therapy, 19 (58%) were visible on [18F]TFB and 30 (91%) on [124I]Iodine imaging. In the patients who underwent redifferentiation therapy, 48 lesions were newly seen on [124I]Iodine PET/CT with a median SUVmax of 3.3 (range, 0.4-285.0). All of these lesions were [18F]TFB-negative.

CONCLUSION

[18F]TFB failed to predict radioactive iodine uptake in patients with poorly differentiated thyroid cancer who underwent redifferentiation therapy with trametinib. It is unclear whether such discrepancies may also occur in other redifferentiation therapies or may even be encountered in redifferentiation-naïve thyroid cancer.

TRIAL REGISTRATION NUMBER

NCT03196518, registered on June 22, 2017.

Poorly differentiated thyroid cancer: Clinical, pathological, mutational, and outcome analysis

INTRODUCTION

Poorly differentiated thyroid cancer (PDTC) remains a challenge not only for pathologists and surgeons because of the difficulties associated with the diagnostic process and the compelling need for difficult thyroidectomy, but it is also of high clinical relevance because it is responsible for mortality in non-anaplastic follicular cell-derived thyroid cancer.

MATERIALS AND METHODS

Cases of PDTC within a 30-year period were reviewed by two independent pathologists. Histological features like atypical mitosis, necrosis, capsular, and vascular invasion were studied. Mutation analysis was done for BRAF, RET/PTC, RAS, and PI3KCA, and P53 was performed using immunohistochemistry.

RESULTS

There were 39 patients with a median age of 53 years; 14 patients were more than 55 years of age. At presentation, 38.4% had compressive features and the median tumor size was 9 cm. At presentation, 67.7% had an extrathyroidal extension (ETE). R0 resection was achieved in 41%, with 12 cases resulting in a difficult thyroidectomy. Necrosis was seen in 65.7% and mitosis in 73.3% with well-differentiated components in 41%. The commonest mutation was RAS (23.1%). Survival was higher in the operable group (54.26, 95% confidence interval [CI]: 30.83-77.70 vs. 20.25, 95% CI: 0-54.07) months, respectively; however, 10-year survival was only 5% and only the tumor size and presence of mitosis were independent risk factors.

CONCLUSION

PDTC presents with worrisome features like large size, ETE, and rapid growth. Aggressive surgical resection with extended/radical thyroidectomy may result in better loco-regional control and improved survival. RAS was the frequent mutation detected. It is worthwhile to identify prognostic factors that can predict the course of PDTC.

Predictive value of hematologic parameters and clinicopathological features of poorly differentiated thyroid carcinoma and anaplastic thyroid carcinoma

PURPOSE

Poorly differentiated thyroid carcinoma (PDTC) and anaplastic thyroid carcinoma (ATC) are rare, aggressive thyroid cancers with poor prognosis. At present, there are a limited number of research reports on PDTC and ATC. The study aimed to analysis the predictive value of hematologic parameters and clinicopathological features of PDTC and ATC.

METHODS

This study retrospectively analyzed 67 patients at Tianjin Medical University Cancer Hospital from 2007 to 2019. We analyzed the clinicopathological features and survival outcomes of PDTC and ATC.

RESULTS

This study showed that positive D-dimer, a high NLR, and a high PLR were more common in death patients. At the end of follow-up, 22 (32.8%) patients were alive at the time of study and 45 (67.2%) patients died from thyroid carcinoma. Disease-related death rates were 93.8% in ATC and 42.9% in the PDTC group. The median overall survival (OS) was 2.5 (0.3-84) months for patients with ATC, and 56 (3-113) months of PDTC patients. Univariate analysis showed that age at diagnosis and surgery were associations with OS in ATC patients, what's more, age at diagnosis, a high NLR, a high PLR, and positive D-dimer were associations with OS in PDTC patients. Multivariate analysis revealed that age at diagnosis was an independent association with OS in ATC patients.

CONCLUSIONS

The hematologic parameters and clinicopathological features may provide predictive value of prognosis for patients with PTDC and ATC.

A Comprehensive Review and Insights into the New Entity of Differentiated High-Grade Thyroid Carcinoma

Differentiated high-grade thyroid carcinoma (DHGTC) is a new subset within the spectrum of thyroid malignancies. This review aims to provide a comprehensive overview of DHGTC, focusing on its historical perspective, diagnosis, clinical characteristics, molecular profiles, management, and prognosis. DHGTC demonstrates an intermediate prognosis that falls between well-differentiated thyroid carcinoma and anaplastic thyroid carcinoma. Previously unenumerated, this entity is now recognized for its significant impact. Patients with DHGTC often present at an older age with advanced disease and exhibit aggressive clinical behavior. Molecularly, DHGTC shares similarities with other thyroid malignancies, harboring driver mutations such as BRAFV600E and RAS, along with additional late mutations. The unique behavior and histologic features of DHGTC underscore the necessity of precise classification for prognostication and treatment selection. This highlights the critical importance of accurate diagnosis and recognition by pathologists to enrich future research on this entity further.

Poorly differentiated thyroid carcinoma: molecular, clinico-pathological hallmarks and therapeutic perspectives

Poorly differentiated thyroid carcinoma (PDTC) is a rare and extremely aggressive tumor, accounting for about 2-15% of all thyroid cancer. PDTC has a distinct biological behavior compared to well-differentiated and anaplastic thyroid carcinoma and, in last years, it has been classified as a separate entity from both anatomopathological and clinical points of view. Nevertheless, there is still a lack of consensus among clinicians regarding inclusion criteria and definition of PDTC that affects its diagnosis and clinical management. Due to its rarity and difficulty in classification compared to other tumors, very few studies are available to date and series often include different histotypes in addition to PDTC. This review focuses on main studies concerning PDTC summarizing the evolution in the definition of its diagnosis criteria, clinicopathological features, management, and outcome. The data available confirm that the pathological evaluation and classification of PDTC are crucial and should therefore be standardized. Since the clinical presentation and prognosis of PDTC may vary widely depending on the different stage of the disease at diagnosis, the patient's management may differ in treatment and should be tailored to each patient. Finally, this review discusses advances in molecular insights of PDTC that, together with the implementation of both in vitro and in vivo models, will provide valuable insights into biological mechanisms of progression, metastasis, and invasion of this aggressive thyroid carcinoma. Further studies on larger, carefully selected series are needed to better assess the peculiar features of PDTC and to better define its management by focusing on the best diagnostic and therapeutic approaches.

Poorly differentiated thyroid carcinomas: conceptual controversy and clinical impact

Poorly differentiated thyroid carcinomas (PDTC) are rare diseases; nevertheless, they account for the majority of deaths from non-anaplastic follicular cell-derived thyroid carcinomas. Establishing the diagnosis and treatment of PDTC is challenging given the low incidence and the lack of standardization of diagnostic criteria. These limitations hamper the ability to compare therapeutic modalities and outcomes between recent and older studies. Recently, the 5th edition of the classification of endocrine tumors has been published, which includes changes in nomenclature and the addition of the disease entity of "differentiated high-grade follicular cell-derived carcinomas". On the other hand, the recently witnessed advances in molecular diagnostics have enriched therapeutic options and improved prognosis for patients. We herein review the various historical variations and evolution in the diagnostic criteria for PDTC. This systematic review attempts to clarify the evolution of the histological and molecular characteristics of this disease, its prognosis, as well as its treatment options.

An Unusual Mixed Thyroid Carcinoma: A Surgical and Pathological Rarity

The incidence of mixed thyroid carcinoma of poorly differentiated thyroid carcinoma (PDTC) and papillary carcinoma thyroid is very unusual. PDTC exhibits a high degree of dedifferentiation and histopathological confirmation is done based on Turin's criteria. This type of carcinoma has a poor prognosis and the survival rates at five and ten years post-diagnosis are significantly lower compared to well-differentiated thyroid carcinomas. Surgery is the best mode of treatment at present. This is a case of a 71-year-old female who underwent total thyroidectomy with modified radical neck dissection which yielded a histopathological variant comprising PDTC and papillary thyroid carcinoma. The patient was followed up with a serial thyroglobulin antibody test and ultrasound of the neck at six months and one year, and both were found to be normal.

Comparative study between poorly differentiated thyroid cancer and anaplastic thyroid cancer: real-world pathological distribution, death attribution, and prognostic factor estimation

Background

The clinic-pathological boundary between poorly differentiated thyroid cancer (PDTC) and anaplastic thyroid cancer (ATC) is unclear due to a wide spectrum of histopathological features and the rarity of the disease. In addition to that, with the highest mortality rate and non-standard treatment modality, the PDTC/ATC population has not been subjected to comprehensive description and comparison with the extent of histological characteristics, therapeutic response, prognostic factors, and death attribution analysis.

Method

A total of 4,947 PDTC/ATC patients from 2000 to 2018 were identified from the Surveillance, Epidemiology, and End Results (SEER) database. Kaplan-Meier survival curve estimation and Cox proportional hazard regression were applied.

Results

Overall, the 5- and 10-year DSS for PDTC were 71.9% and 68.0%, respectively, whereas the 5- and 10-year OS are 59.3% and 51.2%, respectively. The median survival time for ATC patients was 3 months with 1-year OS being 26.9% and 1-year DSS being 31.2%. During the follow-up period, 68.1% of the PDTC/ATC cohort were dead, 51.6% of which were attributed to thyroid malignancies and 16.5% to non-thyroid causes. The top three common non-thyroid causes of death were miscellaneous cancers, lower respiratory system disease, and heart disease. The histological feature of papillary thyroid cancer (PTC) was the leading pathological category for PDTC patients (51.7%), whereas 76.7% of ATC patients' pathological feature was characterized as unidentifiable. Sarcoma histological characteristics found in ATC cases suffer the highest overall mortality (vs. PTC, HR = 2.61, 95% CI 1.68-4.06, P < 0.001). Older age unidentifiable histology feature, more advanced AJCC N1b, AJCC M1, and SEER stage, tumor size larger than 5 cm, and more invasive tumor extension were independent bad outcome predictors.

Conclusion

The populational analysis of the PDTC/ATC cohort has provided reliable support for better understanding of the difference between PDTC and ATC cases and the guidance of clinical practice and further studies.

High Grade Differentiated Follicular Cell-Derived Thyroid Carcinoma Versus Poorly Differentiated Thyroid Carcinoma: A Clinicopathologic Analysis of 41 Cases

Criteria overlap for separating between malignant follicular epithelial cell-derived thyroid gland neoplasms with high grade features of increased mitoses and tumor necrosis but lacking anaplastic histology. Patterns of growth, nuclear features, tumor necrosis, and various mitotic index cutoffs are suggested, but a reproducible Ki-67-based labeling index has not been established. Forty-one cases diagnosed as poorly differentiated thyroid carcinoma (PDTC) or high grade differentiated follicular cell-derived thyroid carcinoma (HGDFCDTC) were reviewed, with histologic features, mitotic figure counts, and Ki-67 labeling index reviewed on cases within Southern California Permanente Medical Group from 2010 to 2021 to establish any potential outcome differences. There were 17 HGDFCDTC (nine papillary thyroid carcinoma; eight oncocytic follicular thyroid carcinoma), median age 64 years, affecting nine females and eight males. Tumors were large (median, 6.0 cm), usually unifocal (n = 13), with only one tumor lacking invasion. Tumor necrosis was present in all; median mitotic count was 5/2 mm² (median Ki-67 labeling index 8.3%). Three patients had metastatic disease at presentation, with additional metastases in four patients (41.2% developed metastases); 11 were without evidence of disease (median 21.2 months); with the remaining six patients alive (n = 4) or dead (n = 2) with metastatic disease (median 25.8 months). Criteria associated with an increased risk of developing metastatic disease: widely invasive tumors; age ≥ 55 years; male; advanced tumor size and stage; extrathyroidal extension; but not increased mitotic rate or higher labeling index. There were 24 PDTC, median age 57.5 years, affecting 13 females and 11 males. Tumors were large (median, 6.9 cm), with 50% part of multifocal disease, with three tumors lacking invasion. Insular/trabecular/solid architecture was seen in all tumors; tumor necrosis was present in 23; and median mitotic count was 6/2 mm² (median Ki-67 labeling index 6.9%). Five patients had metastatic disease at presentation, with additional metastases in 3 patients (29.2% developed metastases); 16 were without evidence of disease (median, 48.1 months); with the remaining 8 patients alive (n = 3) or dead (n = 5) with metastatic disease (median, 22.4 months). Criteria associated with an increased risk of developing metastatic disease: widely invasive tumors; male; advanced tumor size and stage; extrathyroidal extension; but not increased mitotic rate or higher labeling index. HGDFCDTC shows tumor necrosis, a median Ki-67 labeling index of 8.3%, with a high percentage (41%) of patients developing metastatic disease. Extent of invasion (non-invasive, minimally invasive, angioinvasive, widely invasive) correlates strongly with developing metastatic disease. PDTC presents at a slightly younger age, with large tumors, often in a background of multifocal tumors, with tumor necrosis nearly always seen, a median Ki-67 labeling index of 6.9%, with 29% of patients developing metastatic disease. Separation between groups is meaningful as early metastatic disease is relatively common, but mitotic counts/labeling indices are not different between the groups nor able to potentially risk stratify development of metastatic disease.

Newly proposed survival staging system for poorly differentiated thyroid cancer: a SEER-based study

OBJECTIVE

Despite the recent release of the 8th edition TNM staging system, the risk stratification for poorly differentiated thyroid cancer (PDTC) remains controversial.

STUDY DESIGN

Retrospective study.

SETTING

SEER database and the First Hospital of China Medical University (FHCMU) database.

METHODS

Between 2004 and 2015, 1201 PDTC patients from the SEER database were enrolled to propose a new staging system. 38 PDTC patients were included from the FHCMU.

RESULTS

A retrospective analysis of 1201 PDTC cases was performed, and a new staging classification was developed as follows: stage I: age < 55 and T1/any N/M0 (n = 127, 10.57%); stage II: age < 55 and T2-4/any N/M0 or age ≥ 55 and T1-2/any N/M0 (n = 523, 43.55%); stage III: age < 55 and any T/N0/M1 or age ≥ 55 and any T3/any N/M0 (n = 239, 19.90%); stage IV: age < 55 and any T/N1/M1 or age ≥ 55 and T4/any N/M0, and T/any N/M1 (n = 312, 25.98%). The 10-year disease-specific survival rates of patients in the new stages I, II, III, and IV were 97.9%, 77.9%, 35.3%, and 12.1%, respectively. The proportion of variation explained (PVE) for disease-specific survival of the proposed system was higher than that of the 8th AJCC TNM staging (30.61% vs. 27.15%). The accuracy of the staging system was verified in 38 PDTC patients from the FHCMU.

CONCLUSION

The proposed staging system provided a more accurate risk stratification for PDTC patients. The new staging model may facilitate the design of personalized treatment strategies for PDTC patients.

Advances in Thyroid Pathology: High Grade Follicular Cell-derived Thyroid Carcinoma and Anaplastic Thyroid Carcinoma

In the upcoming World Health Organization fifth edition classification of endocrine tumors, there were several major changes related to high grade follicular-derived thyroid carcinoma (HGFCTC) and anaplastic thyroid carcinoma (ATC) based on emerging evidence about the diagnostic criteria clinical behavior, prognostic factors, and molecular signatures of these tumors. In this review, we aim to summarize the major evolutions of HGFCTC and ATC. HGFCTC is a nonanaplastic carcinoma with high grade features (High mitotic count, tumor necrosis). It is subdivided into poorly differentiated thyroid carcinoma diagnosed using the Turin proposal and differentiated high grade thyroid carcinoma. The latter is defined by the presence of the cytoarchitectutal features of well-differentiated thyroid carcinoma (eg, papillae) but harbors elevated mitotic activity and/or tumor necrosis. Poorly differentiated thyroid carcinoma is predominantly RAS -driven and associated with RAI avidity and high propensity for distant metastasis, whereas differentiated high grade thyroid carcinoma is mostly BRAFV600E -driven. ATC may show a wide range of histologic features. Carcinoma of pure squamous phenotype is associated with a high frequency of BRAF V600E mutations and is now considered as a subtype of ATC. There is a stepwise molecular progression from well-differentiated carcinoma to HGFCTC to ATC manifested by 1) early and persistent driver alteration in the MAPK pathway, particularly BRAF V600E and RAS mutations, and 2) gain of secondary aggressive molecular signatures (such as TERT promoter and TP53 mutations) when tumors progress from well-differentiated to high grade to anaplastic carcinoma.

Poorly differentiated thyroid carcinoma: a clinician's perspective

Poorly differentiated thyroid carcinoma (PDTC) is a rare thyroid carcinoma originating from follicular epithelial cells. No explicit consensus can be achieved to date due to sparse clinical data, potentially compromising the outcomes of patients. In this comprehensive review from a clinician's perspective, the epidemiology and prognosis are described, diagnosis based on manifestations, pathology, and medical imaging are discussed, and both traditional and emerging therapeutics are addressed as well. Turin consensus remains the mainstay diagnostic criteria for PDTC, and individualized assessments are decisive for treatment option. The prognosis is optimal if complete resection is performed at early stage but dismal in nearly half of patients with locally advanced and/or distant metastatic diseases, in which adjuvant therapies such as 131I therapy, external beam radiation therapy, and chemotherapy should be incorporated. Emerging therapeutics including molecular targeted therapy, differentiation therapy, and immunotherapy deserve further investigations to improve the prognosis of PDTC patients with advanced disease.

Overview of the 2022 WHO Classification of Thyroid Neoplasms

This review summarizes the changes in the 5th edition of the WHO Classification of Endocrine and Neuroendocrine Tumors that relate to the thyroid gland. The new classification has divided thyroid tumors into several new categories that allow for a clearer understanding of the cell of origin, pathologic features (cytopathology and histopathology), molecular classification, and biological behavior. Follicular cell-derived tumors constitute the majority of thyroid neoplasms. In this new classification, they are divided into benign, low-risk, and malignant neoplasms. Benign tumors include not only follicular adenoma but also variants of adenoma that are of diagnostic and clinical significance, including the ones with papillary architecture, which are often hyperfunctional and oncocytic adenomas. For the first time, there is a detailed account of the multifocal hyperplastic/neoplastic lesions that commonly occur in the clinical setting of multinodular goiter; the term thyroid follicular nodular disease (FND) achieved consensus as the best to describe this enigmatic entity. Low-risk follicular cell-derived neoplasms include non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), thyroid tumors of uncertain malignant potential, and hyalinizing trabecular tumor. Malignant follicular cell-derived neoplasms are stratified based on molecular profiles and aggressiveness. Papillary thyroid carcinomas (PTCs), with many morphological subtypes, represent the BRAF-like malignancies, whereas invasive encapsulated follicular variant PTC and follicular thyroid carcinoma represent the RAS-like malignancies. This new classification requires detailed subtyping of papillary microcarcinomas similar to their counterparts that exceed 1.0 cm and recommends not designating them as a subtype of PTC. The criteria of the tall cell subtype of PTC have been revisited. Cribriform-morular thyroid carcinoma is no longer classified as a subtype of PTC. The term "Hürthle cell" is discouraged, since it is a misnomer. Oncocytic carcinoma is discussed as a distinct entity with the clear recognition that it refers to oncocytic follicular cell-derived neoplasms (composed of > 75% oncocytic cells) that lack characteristic nuclear features of PTC (those would be oncocytic PTCs) and high-grade features (necrosis and ≥ 5 mitoses per 2 mm²). High-grade follicular cell-derived malignancies now include both the traditional poorly differentiated carcinoma as well as high-grade differentiated thyroid carcinomas, since both are characterized by increased mitotic activity and tumor necrosis without anaplastic histology and clinically behave in a similar manner. Anaplastic thyroid carcinoma remains the most undifferentiated form; squamous cell carcinoma of the thyroid is now considered as a subtype of anaplastic carcinoma. Medullary thyroid carcinomas derived from thyroid C cells retain their distinct section, and there is a separate section for mixed tumors composed of both C cells and any follicular cell-derived malignancy. A grading system for medullary thyroid carcinomas is also introduced based on mitotic count, tumor necrosis, and Ki67 labeling index. A number of unusual neoplasms that occur in the thyroid have been placed into new sections based on their cytogenesis. Mucoepidermoid carcinoma and secretory carcinoma of the salivary gland type are now included in one section classified as "salivary gland-type carcinomas of the thyroid." Thymomas, thymic carcinomas and spindle epithelial tumor with thymus-like elements are classified as "thymic tumors within the thyroid." There remain several tumors whose cell lineage is unclear, and they are listed as such; these include sclerosing mucoepidermoid carcinoma with eosinophilia and cribriform-morular thyroid carcinoma. Another important addition is thyroblastoma, an unusual embryonal tumor associated with DICER1 mutations. As in all the WHO books in the 5th edition, mesenchymal and stromal tumors, hematolymphoid neoplasms, germ cell tumors, and metastatic malignancies are discussed separately. The current classification also emphasizes the value of biomarkers that may aid diagnosis and provide prognostic information.

Prognostic Impact of Focal Poorly Differentiated Areas in Follicular Differentiated Thyroid Cancer: Is It a Distinct Entity from Poorly Differentiated Thyroid Cancer?

Poorly differentiated thyroid cancer (PDC) and especially poorly differentiated areas (PDA) within follicular cell-derived differentiated thyroid cancer are ill-defined clinicopathological entities. We report our experience on their comparative prognostic outcomes This is a retrospective study of 61 patients (PDC = 29; PDA = 32) from Endocrine and Metabolic Surgery Department (2009 to 2017). Clinical and follow-up details are collected and digitally tabulated from departmental database. Gender ratio was M:F = 1:1.3 and 1:1.6. Mean age was 51 ± 12 years (16-76) and 54 ± 10.5 years (36-81) in PDA and PDC, respectively. Mean tumour size (4.6 ± 0.9 cm; 4.9 ± 1.2 cm), extrathyroidal invasion (59%; 73%) and regional lymphadenopathy were 50% and 55% in PDA and PDC, respectively. Total thyroidectomy was possible in 94% of PDA and in only 77% of PDC. Radioiodine ablation was utilised in 65% (PDA); 29% (PDC). With mean follow-up of 64 ± 23.5 months (12-103) in PDA and 37 ± 22 months (6-94) in PDC, nodal recurrence (PDC = 29%; PDA = 22%) and systemic metastasis was 41% in PDC (synchronous = 24%; metachronous = 17%); 19% in PDA (synchronous = 16%; metachronous = 3%). Five-year event-free survival (EFS) and overall survival (OS) was 90% and 93% in PDA, and 42% and 44% in PDC, respectively. Our study shows that PDA is a separate clinicopathological entity with significantly positive prognosis compared to PDC.

Postoperative radioiodine therapy impact on survival in poorly differentiated thyroid carcinoma: a population-based study

PURPOSE

The true impact of postoperative radioiodine therapy on survival has been controversial for patients with poorly differentiated thyroid carcinoma (PDTC). We aimed to determine the impact of postoperative radioiodine on survival in PDTC through a population-based study.

METHODS

Data on patients with PDTC were collected from the US SEER database (2004 to 2015). Patients were divided into the radioiodine group and nonradioiodine group. Survival comparison between groups was evaluated by Kaplan-Meier curves, log-rank test and multivariate Cox regression analysis. Akaike information criterion was used to select variables in the nomogram. The performance of the nomogram was assessed by discrimination (C-index) and calibration plots.

RESULTS

The radioiodine group had more aggressive features, such as advanced tumor node metastasis stage and radical surgery, compared to the nonradioiodine group. PDTC patients receiving radioiodine therapy had a significant survival advantage in terms of overall survival (OS) (P = 0.001) but not in terms of cancer-specific survival (P = 0.083). Multivariate analysis revealed radioiodine therapy was an independent favorable factor for OS in PDTC patients (hazard ratio = 0.57; 95% CI, 0.44-0.75, P < 0.001). Subgroup analysis identified patients' characteristics favoring radioiodine therapy. The nomogram (age, tumor size, extension, neck lymph nodes metastasis and radioiodine therapy) of OS for predicting 3-, 5- and 10-year OS probability showed good discrimination (C-index, 0.797) and calibration power.

CONCLUSION

Postoperative radioiodine therapy can prolong the long-term OS in patients with PDTC, and is an independent favorable prognostic factor for those patients. Further prospective studies are warranted.

Expanding the spectrum of thyroid carcinoma with somatic DICER1 mutation: a survey of 829 thyroid carcinomas using MSK-IMPACT next-generation sequencing platform

DICER1 gene encodes an RNaseIII endoribonuclease essential for the cleavage of pre-microRNA to mature microRNA. Germline DICER1 mutation results in DICER syndrome, a cancer predisposition syndrome which manifests in the thyroid gland as early-onset multinodular goiter and increased risk for differentiated thyroid carcinoma. Recently, somatic DICER1 mutations were described in various thyroid neoplasms, including follicular adenoma, papillary thyroid carcinoma, follicular carcinoma, and poorly differentiated thyroid carcinoma. In this study, we identified and described 14 cases (1.7%) with somatic DICER1 mutations from a cohort of 829 patients with thyroid follicular cell-derived thyroid carcinomas which were sequenced using MSK-IMPACT targeted next-generation sequencing platform. We expanded the histologic spectrum of thyroid carcinomas with somatic DICER1 mutations to include Hurthle cell carcinoma, high-grade differentiated thyroid carcinoma, and anaplastic thyroid carcinoma. All patients were adults with a median age of diagnosis of 59 years (range: 22-82). Although rare, a subset of thyroid cancers, including the aggressive subtypes, display somatic DICER1 mutations, some of which have oncogenic potential.

Target Therapy in Thyroid Cancer: Current Challenge in Clinical Use of Tyrosine Kinase Inhibitors and Management of Side Effects

Thyroid cancer (TC) is the most common endocrine malignancy. TC is classified as differentiated TC (DTC), which includes papillary and follicular subtypes and Hürthle cell variants, medullary TC (MTC), anaplastic TC (ATC), and poorly differentiated TC (PDTC). The standard of care in DTC consists of surgery together with radioactive iodine (¹³¹I) therapy and thyroid hormone, but patients with MTC do not benefit from ¹³¹I therapy. Patients with advanced TC resistant to ¹³¹I treatment (RAI-R) have no chance of cure, as well as patients affected by ATC and progressive MTC, in which conventional therapy plays only a palliative role, representing, until a few years ago, an urgent unmet need. In the last decade, a better understanding of molecular pathways involved in the tumorigenesis of specific histopathological subtypes of TC has led to develop tyrosine kinase inhibitors (TKIs). TKIs represent a valid treatment in progressive advanced disease and were tested in all subtypes of TC, highlighting the need to improve progression-free survival. However, treatments using these novel therapeutics are often accompanied by side effects that required optimal management to minimize their toxicities and thereby enable patients who show benefit to continue treatment and obtain maximal clinical efficacy. The goal of this overview is to provide an update on the current use of the main drugs recently studied for advanced TC and the management of the adverse events.

Survival Outcomes and Prognostic Predictors in Patients With Malignant Struma Ovarii

Background: Malignant struma ovarii (MSO) is an extremely rare ovarian malignant tumor and there is limited data on the survival outcomes and prognostic predictors of MSO. The objectives of this study were to investigate the disease-free survival (DFS), overall survival (OS), and disease-specific survival (DSS) rates of patients with MSO, and also evaluate the prognostic factors in this population.

Methods: A retrospective study was conducted and 194 cases of MSO were selected. DFS was assessed by the logistic regression, OS by the Kaplan–Meier method, and DSS was evaluated by the Cox regression.

Results: The median age of these patients was 46.0 years; 142 cases (73.2%) were confined to the ovary and 52 cases (26.8%) had extraovarian metastasis at the initial diagnosis of MSO. During the follow-up, 75.3% of these patients showed no evidence of disease and 18.0% were alive with disease. Only 13 deaths occurred, with 10 attributed to MSO. The 5, 10, and 15-year OS rates were 91.4, 87.7, and 83.5%, respectively. The 5, 10, and 15-year DSS rates were 93.8, 90.0, and 85.7%, respectively. Logistic regression revealed that International Federation of Gynecology and Obstetrics (FIGO) stage IV was the only risk factor for DFS [p < 0.001; odds ratio (OR) 7.328; 95% CI 3.103–16.885, FIGO stage IV vs. stage I; p = 0.021; OR 4.750, 95% CI 1.264–17.856, FIGO stage IV vs. stage II-III]. The multivariate Cox regression analysis showed that poor differentiation was the only risk factor for both OS (p = 0.005, OR 6.406; 95% CI 1.730–23.717) and DSS (p = 0.001, OR 9.664; 95% CI 2.409–38.760), while age ≥45 years was the prognostic predictor for OS (p = 0.038, OR 4.959; 95% CI 1.093–22.508).

Conclusion: Survival outcomes were excellent in patients with MSO, irrespective of the treatment strategy, FIGO stage IV, age ≥45 years, and poor differentiation of tumors were the independent risk factors.

Prognostic significance of neutrophil-to-lymphocyte ratio for long-term outcomes in patients with poorly differentiated thyroid cancer

Poorly differentiated thyroid cancer (PDTC) is a distinct but rare type of thyroid cancer with intermediate biological behavior between differentiated and anaplastic thyroid cancers. PDTC was first defined in 2005 in Japan, but the diagnostic criteria changed in 2015, requiring the tumor to have more than 50% of poorly differentiated components for diagnosis. Because only six years have passed since the PDTC definition change, prognostic factors for long-term survival who meet the latest criteria have not been determined. Neutrophil-to-lymphocyte ratio (NLR) is a prognostic marker in various solid malignancies. However, its impact on PDTC remains unclear. This study aimed to evaluate the significance of NLR as a prognostic factor for patients with PDTC diagnosed based on the latest criteria. In total, 28 PDTC cases (4.4%) of 637 thyroid cancer patients who underwent surgery between 2002 and 2012 were retrospectively analyzed. The median follow-up period was 120 months (range, 7-216 months). Of the 13 deaths (46.4%), 9 patients (32.1%) died from PDTC. The median preoperative NLR was 2.7 (0.67-8.62), and the NLR cut-off value determined by the receiver operating characteristic curve was 2.88. Patients with a high NLR (>2.88) showed significantly worse disease-specific survival (hazard ratio [HR] 4.67, p = 0.036) and overall survival (HR 4.94, p = 0.007) than those with a low NLR (≤2.88). Multivariate analysis revealed that a high NLR independently predicted a worse prognosis (HR 6.06, p = 0.0087). In conclusion, NLR is a useful prognostic marker for patients with PDTC.

Predictive Factors for RAI-Refractory Disease and Short Overall Survival in PDTC

BACKGROUND

The clinical phenotype of poorly differentiated thyroid cancer (PDTC) can vary substantially. We aim to evaluate risk factors for radioiodine refractory (RAI-R) disease and reduced overall survival (OS).

METHODS

We retrospectively screened our institutional database for PDTC patients. For the assessment of RAI-R disease, we included patients who underwent dual imaging with ¹⁸F-FDG-PET and ¹²⁴I-PET/¹³¹I scintigraphy that met the internal standard of care. We tested primary size, extrathyroidal extension (ETE), and age >55 years as risk factors for RAI-R disease at initial diagnosis and during the disease course using uni- and multivariate analyses. We tested metabolic tumor volume (MTV), total lesion glycolysis (TLG) on ¹⁸F-FDG-PET, and the progression of stimulated thyroglobulin within 4-6 months of initial radioiodine therapy as prognostic markers for OS.

RESULTS

Size of primary >40 mm and ETE were significant predictors of RAI-R disease in the course of disease in univariate (81% vs. 27%, p = 0.001; 89% vs. 33%, p < 0.001) and multivariate analyses. Primary tumor size was an excellent predictor of RAI-R disease (AUC = 0.90). TLG/MTV > upper quartile and early thyroglobulin progression were significantly associated with shorter median OS (29.0 months vs. 56.9 months, p < 0.05; 57.8 months vs. not reached p < 0.005, respectively).

DISCUSSION

PDTC patients, especially those with additional risk factors, should be assessed for RAI-R disease at initial diagnosis and in the course of disease, allowing for early implementation of multimodal treatment. Primary tumor size >40 mm, ETE, and age >55 are significant risk factors for RAI-R disease. High MTV/TLG is a significant risk factor for premature death and can help identify patients requiring intervention.

Clinicopathological Characteristics and Prognosis of Poorly Differentiated Thyroid Carcinoma Diagnosed According to the Turin Criteria

OBJECTIVE

Poorly differentiated thyroid carcinoma (PDTC) is the primary cause of death in patients with nonanaplastic follicular cell-derived thyroid carcinoma. We purposed to identify the clinical and pathological characteristics of PDTC and their relationship with prognosis.

METHODS

A retrospective analysis was conducted on patients diagnosed with PDTC at our institution from 2010 to 2018. All of their histopathology slides were reviewed by 2 experienced pathologists based on the Turin criteria. Furthermore, information regarding clinical characteristics, pathological characteristics, treatment strategy, and follow-up events were collected. The Kaplan-Meier method was used for survival analysis, while the log-rank test was used to compare survival curves. Then, the Cox proportional hazards model was used to perform univariate and multivariate analyses.

RESULTS

Twenty-six patients with PDTC who met the Turin criteria were enrolled in this study. The median follow-up period of the included 26 patients was 76 months, while the 3- and 5-year survival rates were 40% and 18%, respectively. Notably, univariate analysis revealed that tumor size >4 cm (P = .038), extrathyroidal extension (ETE) (P = .020), distant metastases (P = .047), poorly differentiated areas >60% (P = .049), and Ki-67 labeling index >30% (P = .040) were associated with poor prognosis. On the other hand, multivariate analysis identified ETE (P = .007) and distant metastases (P = .031) as independent risk factors for poor prognosis.

CONCLUSION

PDTC is a rare carcinoma with high invasiveness and poor prognosis. Patients with ETE or distant metastases may have adverse outcomes.

Pitfalls in Thyroid Cytopathology

Fine-needle aspiration (FNA) is among the first diagnostic tools used in the evaluation of thyroid nodules. It has the ability to triage patients with benign and malignant lesions, thus defining the optimum clinical and/or surgical management. The Bethesda System for Reporting Thyroid Cytopathology has found worldwide acceptance. Thyroid FNA offers high positive predictive value (97%-99%), with sensitivities and specificities of 65% to 99% and 72% to 100%, respectively. Nonetheless, many potential diagnostic pitfalls exist that can lead to false-positive and/or false-negative results. This article discusses several of the potential pitfalls in the cytologic evaluation of thyroid lesions.

Poorly differentiated thyroid carcinoma: An institutional experience

Purpose

The incidence of poorly differentiated thyroid carcinoma (PDTC) is extremely low among thyroid cancers and there is no standardized treatment guideline for it. In this study, we have analyzed PDTC patients and reviewed their clinicopathological features.

Methods

Data of PDTC patients from our institution are collected through the electronic medical database. We analyzed them by several parameters such as basic demographics, presenting symptom, preoperative cytology results, associated pathology, surgical results, surgery type, and distant metastasis.

Results

We collected 23 cases in our institution. Apart from two patients who were transferred to another hospital upon diagnosis, all 21 operated cases are analyzed. The parameters we studied were age, sex, presenting symptoms, distant metastasis and pathological features such as tumor size, associated pathology, predominant pattern and so on. We also provided descriptive analyses according to the type of presentation and treatment; patients with distant metastasis, juvenile cancer, and concurrent hyperthyroidism. Furthermore, we provided different cases in which the initial surgical plans differed.

Conclusion

We present 21 cases of PDTC patients and clarify their clinicopathological features. Despite some limitations, this study may shed light for future research regarding treatment of PDTC patients.

The American Association of Endocrine Surgeons Guidelines for the Definitive Surgical Management of Thyroid Disease in Adults

OBJECTIVE

To develop evidence-based recommendations for safe, effective, and appropriate thyroidectomy.

BACKGROUND

Surgical management of thyroid disease has evolved considerably over several decades leading to variability in rendered care. Over 100,000 thyroid operations are performed annually in the US.

METHODS

The medical literature from 1/1/1985 to 11/9/2018 was reviewed by a panel of 19 experts in thyroid disorders representing multiple disciplines. The authors used the best available evidence to construct surgical management recommendations. Levels of evidence were determined using the American College of Physicians grading system, and management recommendations were discussed to consensus. Members of the American Association of Endocrine Surgeons reviewed and commented on preliminary drafts of the content.

RESULTS

These clinical guidelines analyze the indications for thyroidectomy as well as its definitions, technique, morbidity, and outcomes. Specific topics include Pathogenesis and Epidemiology, Initial Evaluation, Imaging, Fine Needle Aspiration Biopsy Diagnosis, Molecular Testing, Indications, Extent and Outcomes of Surgery, Preoperative Care, Initial Thyroidectomy, Perioperative Tissue Diagnosis, Nodal Dissection, Concurrent Parathyroidectomy, Hyperthyroid Conditions, Goiter, Adjuncts and Approaches to Thyroidectomy, Laryngology, Familial Thyroid Cancer, Postoperative Care and Complications, Cancer Management, and Reoperation.

CONCLUSIONS

Evidence-based guidelines were created to assist clinicians in the optimal surgical management of thyroid disease.

Poorly differentiated thyroid carcinoma

Poorly differentiated thyroid carcinoma (PDTC) is an aggressive form of follicular cell derived thyroid carcinoma with a prognosis intermediate between the indolent well differentiated thyroid carcinomas and the rapidly growing often fatal anaplastic carcinoma. While all investigators agree on the presence of this entity, there is disagreement in regard to its definition. In 2006, a set of criteria based solely on mitotic index ≥5/10 high power fields and/or tumor necrosis was proposed by a group of researchers from Memorial Sloan Kettering Cancer Center (MSKCC criteria) in New York. A year later, alternative diagnostic criteria of PDTC, so called the Turin proposal, were advocated by an international consensus group. The Turin proposal requires three criteria: 1) solid/trabecular/insular growth pattern; 2) absence of nuclear features of papillary carcinoma; and 3) at least one of the following three features: mitotic index ≥3/10 high power fields (HPFs), necrosis, or convoluted nuclei. In this review, we summarize the histology, diagnostic criteria (Turin proposal and MSKCC criteria) with their pros and cons, the prognostic factors, and molecular profile of PDTC, aiming to provide a practical and compreshensive review of this challenging entity.

Poorly differentiated thyroid carcinoma (PDTC) characteristics and the efficacy of radioactive iodine (RAI) therapy as an adjuvant treatment in a tertiary cancer care center

BACKGROUND

Poorly differentiated thyroid cancer (PDTC) is biologically more aggressive. Surgery remains the mainstay of treatment. The utility of radioactive iodine (RAI) after surgery is unclear.

METHODS

In this retrospective study, patients treated between Jan 2012 and Dec 2017 were included. The demographic, clinical and treatment-related details, including RAI ablation, were recorded and their survival analyzed.

RESULTS

Thirty-five patients fulfilled the eligibility criteria. Majority was treatment naïve at presentation. All patients underwent surgery followed by RAI ablation, with a cumulative median dose of 220 mCi (range 40-1140). Sixteen patients received more than one radioiodine treatment for distant metastases. Incomplete resection, age > 45 years and the presence of distant metastasis influenced survival the most. The 3-year PFS of patients with PDTC was 69%.

CONCLUSION

All patients in our series showed uptake and responded to treatment. Further use of molecular markers and functional molecular imaging would better our understanding of this entity.

Histopathology and immunohistochemistry as prognostic factors for poorly differentiated thyroid cancer in a series of Polish patients

Background

Poorly differentiated thyroid cancer (PDTC) is a rare but aggressive type of thyroid cancer (TC) and the main cause of death from non-anaplastic follicular cell-derived TC. Although the Turin criteria are well defined, the pathological features that could serve as diagnostic and prognostic factors remain controversial.

Materials and methods

Forty-nine consecutive PDTC cases were identified in a single cancer center between 2000 and 2018. We analyzed the impact of routine histopathological and immunohistochemical features and several parameters that are not routinely included in pathology reports such as the presence of atypical mitoses, the amount of necrosis, or insulin-like growth factor-II mRNA-binding protein 3 immunostaining on the survival of patients with PDTC. Overall survival (OS) and disease-specific survival (DSS) were calculated using the Kaplan-Meier method.

Results

Of the 49 PDTC 34 (69.4%) showed the insular pattern of growth. The median of poorly differentiated area was 95% (range, 1–100), and 30 (61.2%) patients had a predominant (>50%) insular area. The 5-year OS and DSS rates at a median follow-up of 57 months were 60.6% and 64.3%, respectively. Univariate analysis showed that tumor size >4 cm, presence of atypical mitoses, Ki-67 >5%, and thyroglobulin (Tg)-negative immunostaining were associated with a higher risk of PDTC-related death. Atypical mitoses and Tg negativity were independent factors of worse DSS in multivariate analysis. Patients with insular and predominant insular areas showed a 3- and 6-fold higher risk of PDTC death when they displayed atypical mitoses.

Conclusions

In PDTC, the presence of atypical mitoses may be helpful in identifying patients with poorer outcome and worth including in pathology reports, particularly in tumors with a dominant insular pattern of growth. Additionally, the inclusion of Tg immunostaining may be considered in a prognostic context, and not only as a diagnostic feature.

New Therapies for Advanced Thyroid Cancer

Thyroid cancer is the most common endocrine cancer. The discovery of new biomarkers for thyroid cancer has significantly improved the understanding of the molecular pathogenesis of thyroid cancer, thus allowing more personalized treatments for patients with thyroid cancer. Most of the recently discovered targeted therapies inhibit the known oncogenic mechanisms in thyroid cancer initiation and progression such as MAPK pathway, PI3K/Akt-mTOR pathways, or VEGF. Despite the significant advances in molecular testing and the discoveries of new and promising therapeutics, effective treatments for advanced and metastatic, iodine-refractory thyroid cancer are still lacking. Here, we aim to summarize the current understanding of the genetic alterations and the dysregulated pathways in thyroid cancer and to discuss the most recent targeted therapies and immunotherapy for advanced thyroid cancer with a promising anti-tumor activity and clinical benefit.

Prognostic Impact of the Turin Criteria in Poorly Differentiated Thyroid Carcinoma

BACKGROUND

The Turin criteria including solid, trabecular, and/or insular architecture, lack of typical nuclear features of papillary carcinoma, and mitoses, necrosis, or convoluted nuclei were adopted in the recent 4th edition of the World Health Organization classification published in 2017.

MATERIALS AND METHODS

Between 2006 and 2017, 11,001 cases underwent initial surgery for primary malignant thyroid tumor derived from follicular cells. A total of 75 (0.7%) cases were diagnosed with PDTC according to the 2004 WHO classification. Based on the Turin criteria, 30 (40%) cases were re-classified as PDTC-Turin (+) and 45 (60%) cases were PDTC-Turin (-). Clinicopathological features and prognosis were compared between PDTC-Turin (+) and PDTC-Turin (-).

RESULTS

Seventy-five patients (48 females and 27 males) had a median age at the time of surgery of 57 years. Preoperative diagnosis was benign in 16 (21%), follicular tumor in 40 (53%), and malignant in 19 (25%). The 5-year cause-specific survival (CSS) and disease-free survival (DFS) rates were 97% and 44% for PDTC-Turin (+) and 100% and 88% for PDTC-Turin (-). On univariate analysis, CSS and DFS rates were significantly worse in the PDTC-Turin (+) than in the PDTC-Turin (-) (p = 0.0096, and p = 0.0016). Multivariate analysis showed that Turin criteria status, Ki-67 labeling index ≥ 10%, and age 55 ≥ years were the independent prognostic factors for recurrence.

CONCLUSIONS

The prevalence of PDTC diagnosed with the Turin criteria was low, but it showed more aggressive behavior. The 2017 WHO classification reflects the prognosis more accurately than the 2004 WHO classification.

BRAF Inhibitors in Thyroid Cancer: Clinical Impact, Mechanisms of Resistance and Future Perspectives

The Kirsten rat sarcoma viral oncogene homolog (RAS)/v-raf-1 murine leukemia viral oncogene homolog 1 (RAF)/mitogen-activated protein kinase 1 (MAPK) signaling cascade is the most important oncogenic pathway in human cancers. Tumors leading mutations in the gene encoding for v-raf murine sarcoma viral oncogene homolog B (BRAF) serine-threonine kinase are reliant on the MAPK signaling pathway for their growth and survival. Indeed, the constitutive activation of MAPK pathway results in continuous stimulation of cell proliferation, enhancement of the apoptotic threshold and induction of a migratory and metastatic phenotype. In a clinical perspective, this scenario opens to the possibility of targeting BRAF pathway for therapy. Thyroid carcinomas (TCs) bearing BRAF mutations represent approximately 29–83% of human thyroid malignancies and, differently from melanomas, are less sensitive to BRAF inhibitors and develop primary or acquired resistance due to mutational events or activation of alternative signaling pathways able to reactivate ERK signaling. In this review, we provide an overview on the current knowledge concerning the mechanisms leading to resistance to BRAF inhibitors in human thyroid carcinomas and discuss the potential therapeutic strategies, including combinations of BRAF inhibitors with other targeted agents, which might be employed to overcome drug resistance and potentiate the activity of single agent BRAF inhibitors.

Prognostic Significance of Extent of Invasion in Poorly Differentiated Thyroid Carcinoma

Background: The 2017 World Health Organization (WHO) Classification of Tumors of Endocrine Organs defines poorly differentiated thyroid carcinoma (PDTC) as a tumor with conventional criteria of malignancy (capsular penetration or vascular invasion) with solid, insular, or trabecular growth, a lack of nuclear features of papillary thyroid carcinoma, and increased mitotic activity, tumor necrosis, or convoluted nuclei. The extent of invasion has been shown to be prognostic in follicular thyroid carcinoma and Hürthle cell carcinoma. Our aim was to evaluate how extent of invasion impacts clinical outcome for PDTC. Methods: We retrospectively identified 47 consecutively diagnosed cases of PDTC that were resected between 2005 and 2018. All cases were reviewed to confirm that the tumors met the 2017 Endocrine WHO criteria of PDTC. In addition, tumors were categorized as follows: encapsulated with capsular penetration only, encapsulated with focal vascular invasion (fewer than four foci), encapsulated with extensive vascular invasion (four or more foci), or widely invasive. Histopathologic characteristics and clinical outcome data were recorded. Results: A total of 47 cases of PDTC, including 15 oncocytic tumors, were identified from 28 (60%) women and 19 (40%) men (mean age of 57 years at diagnosis). The mean tumor size was 4.3 cm. Mitoses numbered 8 per 10 high-power fields (HPF) on average (range: 1-34), and necrosis was present in 21 (45%) cases. Eight (17%) cases were encapsulated with capsular penetration only, 5 (11%) were encapsulated with focal vascular invasion, 18 (38%) were encapsulated with extensive vascular invasion, and 16 (34%) were widely invasive. Of the 42 (89%) patients with follow-up data, 7 (17%) died of disease (with a mean survival time of 6.4 years), 11 (26%) have distant metastatic disease, and 24 (57%) have no evidence of disease (mean follow-up 5.6 years). Eight (19%) patients presented with M1 disease at diagnosis. The 5-year disease-free survival (DFS) for patients with M0 disease at diagnosis was 100% for patients with tumors with capsular invasion only or focal vascular invasion (n = 7), 73% for patients with encapsulated tumors with extensive vascular invasion (n = 11), and 17% for patients with widely invasive PDTCs (n = 6). DFS estimates by Kaplan-Meier analysis were significantly different between these groups (p = 0.0016). Conclusions: Extent of invasion appears to be an important parameter that affects clinical outcome for patients with PDTC. In our cohort, patients with encapsulated PDTC with capsular invasion only or focal vascular invasion had an excellent outcome.

Poorly differentiated thyroid cancer in the context of the revised 2015 American Thyroid Association Guidelines and the Updated American Joint Committee on Cancer/Tumor-Node-Metastasis Staging System (eighth edition)

OBJECTIVE

Poorly differentiated thyroid cancer (PDTC) is a rare, but aggressive thyroid cancer (TC) and a main cause of death from non-anaplastic follicular cell-derived TC. Assessing the risk of PDTC-related death and the risk of recurrence is important for clinicians. The recent American Thyroid Association (ATA) 2015 guidelines and the updated 8th edition of the American Joint Committee on Cancer/Tumor-Node-Metastasis (AJCC/TNM) staging system should support clinicians in the management approach to PDTC patients.

PATIENTS

Forty-six consecutive PDTC patients treated in a single oncologic centre, 2000-2017.

MEASUREMENTS

Retrospective analysis of TNM stage, initial risk, response-to-therapy categories, follow-up and final disease status incorporating the ATA 2015 criteria and the 8th AJCC/TNM staging system. Disease-specific survival (DSS) using the Kaplan-Meier method.

RESULTS

Of the 46 PDTC 21 (45.6%) were ATA high risk (HR), 22 (47.8%), 17 (37%) and seven (15.2%) were TNM stages I, II, and III-IV, respectively. During a median follow-up of 55.5 months, two (4.3%) patients were recurrent, 18 (39.1%) died of PDTC. The 5-/10-year DSS were 65/57%, respectively. According to the AJCC/TNM, the 5-/10-year DSS of I, II, and III-IV stage were 83/83%; 77/55%, and 0/0%, respectively. According to the 2015 ATA initial risk, the 5-/10-year DSS were 91/72% for ATA intermediate risk and 38/38% for ATA HR patients.

CONCLUSIONS

In PDTC patients, the updated AJCC/TNM staging system accurately predicts a high risk of death in stage III-IV, whereas it seems to be inadequate for predicting a very low or low risk of death expected for differentiated TC in stage I-II. The ATA initial HR may be also used to predict a high risk of PDTC-related death.

Cytologic features of aggressive variants of follicular-derived thyroid carcinoma

Certain carcinomas of the thyroid gland behave aggressively resulting in increased patient morbidity and poor patient prognosis. The diagnosis of these aggressive thyroid cancer subtypes is sometimes challenging and subject to increased interobserver variability. This review deals with the cytological features of such tumors including aggressive variants of papillary thyroid carcinoma, poorly differentiated thyroid carcinoma, and anaplastic thyroid carcinoma. These malignancies fall into 2 groups based on their cytomorphology: those that exhibit distinct microscopic features (eg, nuclear findings typical of classical papillary thyroid carcinoma or marked anaplasia) and those that present with more subtle cytologic features (eg, nuclear pseudostratification, "soap bubble" nuclei, supranuclear or subnuclear cytoplasmic vacuoles, rosette-like structures, hobnail cells). We review the literature regarding these aggressive thyroid cancers and highlight important phenotypic characteristics that can be useful for their diagnosis based on fine needle aspiration.

Salidroside inhibits migration and invasion of poorly differentiated thyroid cancer cells

Background

No effective treatment is currently available for poorly differentiated thyroid cancer which is resistant to radioiodine, especially with migration and invasion. A great number of researches have revealed the anticancer effects of salidroside, but none have studied the effects of salidroside on thyroid cancer. This study aimed to investigate the effect of salidroside on migration and invasion of poorly differentiated thyroid cancer cells.

Methods

The effects of salidroside on migration, invasion and apoptosis of poorly differentiated thyroid cancer WRO cells and normal thyroid follicular epithelial Nthy‐ori 3‐1 cells were measured by wound‐healing assay, transwell migration/invasion assay and flow cytometry, respectively. The expression levels of MMP2 and MMP9 at RNA and protein levels in WRO cells were detected by qRT‐PCR and western blot. The phosphorylation levels of Janus kinase 2 (JAK2), signal transducer and activator of transcription 3 (STAT3) and the apoptosis‐related protein levels of Bax, cleaved caspase 3 and Bcl‐2 were assessed by western blot.

Results

Salidroside significantly suppressed migration/invasion and induced apoptosis in poorly differentiated thyroid cancer WRO cells. We further illustrated that salidroside significantly inhibited expressions of MMP2 and MMP9 at mRNA and protein levels and the phosphorylation activation of JAK2/STAT3 in WRO cells. In addition, salidroside increased expressions of pro‐apoptotic factors (Bax and cleaved caspase 3) and decreased expression of anti‐apoptotic factor (Bcl‐2) significantly in WRO cells.

Conclusion

The present study demonstrates that salidroside inhibits migration and invasion of WRO cells (a kind of poorly differentiated cancer cell line) significantly, which might be via suppressing JAK2‐STAT3 signaling pathway.

Clinical impact of a cytological screening system using cyclin D1 immunostaining and genomic analysis for the diagnosis of thyroid nodules

Background

Fine-needle aspiration (FNA) is the most reliable method for diagnosing thyroid nodules; however, some features such as atypia of undetermined significance or follicular lesion of undetermined significance can confound efforts to identify malignancies. Similar to BRAF, cyclin D1 may be a strong marker of cell proliferation.

Methods

One hundred two patients with thyroidal nodule were enrolled in this prospective study.

Expression of cyclin D1 in thyroid nodules was determined by immunohistochemistry using both surgical specimens and their cytological specimens. The identification of the optimal cut off points for the diagnosis of malignancy were evaluated using the receiver operating characteristic (ROC) curves and the assessment of the area under the ROC curve (AUC). The specificity, sensitivity, positive predictive value (PPV) of markers were evaluated from crosstabs based on cut off points and significance were calculated. We also analyzed genetic variants by target NGS for thyroid nodule samples.

Results

The positive predictive value (PPV) and median stain ratio (MSR) of cyclin D1 nuclear staining was determined in papillary thyroid carcinoma (PPV = 91.5%, MSR = 48.5%), follicular adenoma (PPV = 66.7%, MSR = 13.1%), and adenomatous goiter and inflammation controls (MSR = 3.4%). In FNA samples, a threshold of 46% of immunolabelled cells allows to discriminate malignant lesions from benign ones (P < 0.0001), with 81% sensitivity and 100% specificity. A 46% cutoff value for positive cyclin D1 immunostaining in thyroid cells demonstrated 81% sensitivity and 100% specificity. In surgical specimens, ROC curve analysis showed a 5.8% cyclin D1 immunostaining score predicted thyroid neoplasms at 94.4% sensitivity and 92.3% specificity (P = 0.003), while a 15.7% score predicted malignancy at 86.4% sensitivity and 80.5% specificity (P < 0.0001). Finally, three tested clinico-pathological variables (extra thyroidal extension, intraglandular metastasis, and lymph node metastasis) were significant predictors of cyclin D1 immunostaining (P < 0.001).

Conclusion

Our cytological cyclin D1 screening system provides a simple, accurate, and convenient diagnostic method in precision medicine enabling ready determination of personalized treatment strategies for patients by next generation sequencing using cytological sample.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5452-4) contains supplementary material, which is available to authorized users.

Poorly Differentiated Carcinoma of the Thyroid Gland: Current Status and Future Prospects

BACKGROUND

Poorly differentiated thyroid cancer (PDTC) is a rare but clinically highly significant entity because it accounts for most fatalities from non-anaplastic follicular cell-derived thyroid cancer. Due to the relative rarity of the disease and heterogeneous diagnostic criteria, studies on PDTC have been limited. In light of the evolution of ultra-deep next-generation sequencing technologies and through correlation of clinicopathologic and genomic characteristics of PDTC, an improved understanding of the biology of PDTC has been facilitated. Here, the diagnostic criteria, clinicopathologic characteristics, management, and outcomes in PDTC, as well as genomic drivers in PDTC reported in recent next-generation sequencing studies, are reviewed. In addition, future prospects in improving the outcomes in PDTC patients are reviewed.

SUMMARY

PDTC patients tend to present with adverse clinicopathologic characteristics: older age, male predominance, advanced locoregional disease, and distant metastases. Surgery with clearance of all gross disease can achieve satisfactory locoregional control. However, the majority of PDTC patients die of distant disease. Five-year disease-specific survival for PDTC patients has been reported at 66%. On multivariate analysis, reported predictors of poor survival in PDTC patients have been older age (>45 years), T4a pathological stage, extrathyroidal extension, high mitotic rate, tumor necrosis, and distant metastasis at presentation. BRAF^V600E or RAS mutations (27% and 24% of cases, respectively) remain mutually exclusive main drivers in PDTC. TERT promoter mutations represent the most common alteration in PDTC (40%). Mutation in translation initiation factor EIF1AX (11%) and tumor suppressor TP53 (16%) have also been reported in PDTC. High rates of novel mutations (MED12 and RBM10) have been reported in fatal PDTC (15% and 12%, respectively). Chromosome 1q gains represent the most common arm-level alterations in PDTC, and those patients show worse survival rates. Chromosome 22q losses are also found in PDTC and show strong association with RAS mutation.

CONCLUSIONS

These new insights into the clinicopathologic and molecular characteristics of PDTC, together with further advancement in ultra-deep sequencing technologies, will be conducive in narrowing the focus in order to develop novel targeted therapies and improve the outcomes in PDTC patients.

An Unusual Case of Metastatic Follicular Thyroid Cancer 40 Years after Initial Diagnosis

Thyroid cancer recurrence can occur decades after initial diagnosis despite excellent response to therapy. Thyroid cancer recurrence is evaluated using serum thyroglobulin (Tg) and imaging studies including I-131 WBS and neck ultrasound. Limitations in Tg measurement and WBS may result in failure to detect recurrence. We report the case of a 63-year-old man who was noted to have rhonchi during a routine visit. He had a past history of follicular thyroid cancer that was diagnosed 40 years ago and treated with total thyroidectomy and radioactive iodine. He had excellent response to therapy with undetectable Tg levels, normal neck ultrasounds, and multiple negative whole body scans (WBS) due to which he was discharged from endocrinology clinic after 37 years of follow-up. Chest X-ray revealed a left lung mass with biopsy positive for thyroid cancer. Tg remained undetectable with negative anti-Tg antibody. Left pneumonectomy was done which revealed a mix of 70% differentiated thyroid cancer and 30% poorly differentiated/anaplastic thyroid cancer. He received two cycles of Doxorubicin and Paclitaxel. At 4 months follow-up after surgery, he had 3 subcentimeter nodules in his right lung. This case highlights that physical exam remains an essential tool to evaluate for recurrence. Since the lungs are the most common site of metastasis in follicular thyroid cancer, a chest X-ray may help detect metastasis that is missed on other modalities.

Poorly Differentiated Thyroid Carcinoma Patients with Detectable Thyroglobulin Levels after Initial Treatment Show an Increase in Mortality and Disease Recurrence

PURPOSE

The role of thyroglobulin (Tg) in predicting death and recurrence risk in patients with poorly differentiated thyroid carcinoma (PDTC) is not well established. We aimed to analyze Tg levels following total thyroidectomy and adjuvant radioiodine treatment (RAI) in PDTC patients and correlate Tg levels with survival and recurrence.

METHODS

A retrospective analysis was conducted on 101 patients with PDTC who were treated between 1986 and 2010. Among them, 38 had no distant metastases at presentation, were managed by total thyroidectomy and adjuvant RAI, and had negative anti-Tg antibodies. An unstimulated Tg level < 1 ng/mL was used as a cut-off point for undetectable Tg levels. Association of patient and tumor characteristics with Tg levels was examined by χ² test. Overall survival, disease-specific survival (DSS), and recurrence-free survival (RFS), stratified by Tg levels, were calculated by the Kaplan-Meier method and compared by the log-rank test.

RESULTS

Compared to patients with undetectable Tg, cases with detectable Tg had a lower probability of achieving free surgical margins (21.7 vs. 46.7%; p = 0.04), higher node status (73.3 vs. 21.8%; p = 0.005), decreased 5-year DSS (65 vs. 100%; p = 0.009), and worse 5-year RFS (32 vs. 84%, p = 0.010), with a significant number of patients having a recurrence in the first year (50 vs. 12.5%; p = 0.021). Patients with detectable Tg levels also showed worse locoregional (55.6 vs. 90.9%; p = 0.014) and distant control (5-year distant control of 46.9 vs. 91%; p = 0.017).

CONCLUSIONS

Our results suggest that detectable Tg levels after surgery and RAI in a subset of PDTC patients appear to predict a higher rate of death and recurrence.

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.

Follow-up of differentiated thyroid cancer - what should (and what should not) be done

The treatment paradigm for thyroid cancer has shifted from a one-size-fits-all approach to more personalized protocols that range from active surveillance to total thyroidectomy followed by radioiodine remnant ablation. Accurate surveillance tools are available, but follow-up protocols vary widely between centres and clinicians, owing to the lack of clear, straightforward recommendations on the instruments and assessment schedule that health-care professionals should adopt. For most patients (that is, those who have had an excellent response to the initial treatment and have a low or intermediate risk of tumour recurrence), an infrequent assessment schedule is sufficient (such as a yearly determination of serum levels of TSH and thyroglobulin). Select patients will benefit from second-line imaging and more frequent assessments. This Review discusses the strengths and weaknesses of the surveillance tools and follow-up strategies that clinicians use as a function of the initial treatment and each patient's risk of recurrence.

Special types of thyroid carcinoma

This article reviews the small percentage of thyroid tumours that are not classified as classic papillary thyroid carcinoma, follicular thyroid carcinoma, and medullary thyroid carcinoma. It includes subtypes of papillary thyroid carcinoma, including, tall-cell, hobnail/micropapillary, columnar cell, diffuse sclerosing and solid variants. Poorly differentiated carcinoma, high-grade carcinoma and anaplastic thyroid carcinoma are reviewed. Also discussed are entities that are unusual but need to be recognized as primary thyroid neoplasms, i.e. mucoepidermoid carcinoma, sclerosing mucoepidermoid carcinoma with eosinophilia, and mammary analogue secretory carcinoma/secretory carcinoma. The pathological features and prognostic factors are described; a brief review of molecular correlates of these neoplasms is included.

LOX is a novel mitotic spindle-associated protein essential for mitosis

LOX regulates cancer progression in a variety of human malignancies. It is overexpressed in aggressive cancers and higher expression of LOX is associated with higher cancer mortality. Here, we report a new function of LOX in mitosis. We show that LOX co-localizes to mitotic spindles from metaphase to telophase, and p-H3(Ser10)-positive cells harbor strong LOX staining. Further, purification of mitotic spindles from synchronized cells show that LOX fails to bind to microtubules in the presence of nocodazole, whereas paclitaxel treated samples showed enrichment in LOX expression, suggesting that LOX binds to stabilized microtubules. LOX knockdown leads to G2/M phase arrest; reduced p-H3(Ser10), cyclin B1, CDK1, and Aurora B. Moreover, LOX knockdown significantly increased sensitivity of cancer cells to chemotherapeutic agents that target microtubules. Our findings suggest that LOX has a role in cancer cell mitosis and may be targeted to enhance the activity of microtubule inhibitors for cancer therapy.

Application of intensity-modulated radiotherapy in unresectable poorly differentiated thyroid carcinoma

Poorly differentiated thyroid carcinoma (PDTC) is a rare and aggressive malignancy with high rates of invasion and distant metastasis. This study was to explore the ability of intensity-modulated radiotherapy (IMRT) combined with chemotherapy to manage unresectable PDTC. Between February 2011 and April 2012, 5 patients with unresectable PDTC were treated by IMRT at our institution and were included in this analysis. The median radiotherapy dose to the gross tumor volume (GTV) was 66 Gy/33 fractions/6.4 weeks. All patients received chemotherapy, and one patient with tumor compression symptoms had a tracheotomy before treatment. The mean survival time of the 5 patients was 41.6 months. The direct causes of death were distant metastases (40%) and progression of the locoregional disease (20%). In conclusion, IMRT combined with chemotherapy for unresectable PDTC might be beneficial to improve locoregional control. Further new therapies are needed to control metastases.

Poorly Differentiated Thyroid Carcinoma: 10-Year Experience in a Southeast Asian Population

BACKGROUND

No previous studies have been published on poorly differentiated thyroid carcinoma (PDTC) in Southeast Asia.

METHODS

We included all adult PDTC patients diagnosed using the Turin criteria at the Philippine General Hospital from 2006 to 2015. The data collected included demographics, clinical presentation, histopathology, treatment, and outcomes. Tests of association were employed to compare these data with foreign studies on PDTC, as well as with local studies on well differentiated thyroid carcinoma (WDTC) and anaplastic thyroid carcinoma (ATC).

RESULTS

Eighteen PDTC cases were identified. The median age was 62 years old, with the majority being females. All patients had goiter on presentation, and most were stage IV at the time of diagnosis. In terms of PDTC subtype, insular and trabecular patterns were equally common. Extrathyroidal extension was documented in eight patients, while five patients each had nodal and distant metastasis. All but one patient underwent surgery; however, less than half received adjuvant radioiodine therapy. The 5-year survival rate was 83%. Three patients (16.7%) died at a median of 12 months after diagnosis. Nine (50%) are still alive with persistent and/or recurrent disease at a median of 39 months after diagnosis.

CONCLUSION

The behavior of PDTC in this Southeast Asian population was found to be similar to patterns observed in other regions, and exhibited intermediate features between WDTC and ATC. Appropriate surgery provided excellent 5-year survival rates, but the role of adjuvant therapy remains unclear. Larger studies are needed to identify prognostic factors in this population.