Follicular thyroid carcinoma: differences in clinical relevance between minimally invasive and widely invasive tumors

[Update on follicular thyroid cancer-What is relevant for surgeons?]

Follicular thyroid cancer (FTC) is the second most frequent form of differentiated thyroid cancer, accounting for approximately 5-15% of all thyroid malignancies. According to the World Health Organization (WHO) classification from 2022 FTC is divided into three subtypes, which clearly differ in the overall prognosis and probability of recurrence. Furthermore, knowledge about benign follicular tumors and low-grade neoplasms is important. Prognostic factors for malignant alterations include patient age, tumor size, invasive growth, the presence of angioinvasion and the occurrence of distant metastases. The surgical management is guided by these factors and therefore varies between the different FTC subtypes. In summary, a precise understanding of the individual subtypes of thyroid tumors is essential to be able to make an appropriate and personalized decision on surgical treatment.

Prognostic Factors for Cancer-Specific Survival and Disease-Free Interval in 130 Patients with Follicular Thyroid Carcinoma: Single Institution Experience

BACKGROUND

Follicular thyroid carcinoma (FTC) is categorized into three groups: minimally invasive FTC (MIFTC), encapsulated angioinvasive FTC (EAIFTC), and widely invasive FTC (WIFTC). FTC is the second most common type of thyroid tumor, though it remains relatively rare in the general population. This study aimed to examine the prognosis and prognostic factors in patients with follicular thyroid carcinoma.

METHODS

Data were obtained from a tertiary referral center for 130 FTC patients, covering the period from 1995 to 2020. Clinical data included demographic characteristics, tumor features, type of surgery, tumor recurrence, and vital status. Descriptive statistical methods, Kaplan-Meier survival curves, and Cox proportional hazard regression were used for statistical analysis to identify independent predictors.

RESULTS

Distant metastases occurred in 12 patients during the follow-up period. The 5-year, 10-year, 15-year, and 20-year cancer-specific survival (CSS) rates were 98.1%, 92.3%, 83.5%, and 79.8%, respectively. Independent unfavorable prognostic factors for CSS included widely invasive tumor type (hazard ratio [HR] 3.63, 95% CI 1.29-10.18), multifocality (HR 6.7, 95% CI 1.37-32.72), and presence of distant metastases (HR 2.29, 95% CI 1.08-4.84). When disease-free interval (DFI) was considered, the 5-year, 10-year, 15-year, and 20-year rates were 92.3%, 85.3%, 82.0%, and 76.6%, respectively. Independent unfavorable prognostic factors for DFI were widely invasive tumor type (HR 2.53, 95% CI 1.02-6.28) and tumor multifocality (HR 7.69, 95% CI 1.07-55.17).

CONCLUSIONS

The 10-year survival rate for patients with FTC is relatively favorable. Factors associated with poorer prognosis include the presence of distant metastases, WIFTC, and multifocality. Factors linked to disease recurrence are WIFTC and multifocality.

Management of follicular thyroid carcinoma

Follicular thyroid carcinoma (FTC) is the second most common histological type of thyroid carcinoma. This review aims to summarize the available evidence and guidelines and provide an updated consensus regarding the management of FTC. The cytoarchitectural features of FTC are similar to those of follicular adenoma (FA), and it is difficult to preoperatively distinguish between FA and FTC. For nodules with Bethesda class III-V cytology, molecular test results (if available) should be considered before the operation. However, it should be noted that molecular tests are not available in all countries. The goals of initial surgical therapy for patients with FTC are to improve overall and disease-specific survival, reduce the risk of persistent/recurrent disease and associated morbidity, and permit accurate disease staging and risk stratification while minimizing treatment-related morbidity and unnecessary therapy. Previous studies have reported some prognostic factors such as distant metastasis, age, tumor size, vascular invasion, TERT promoter mutation, and histological subtype. In particular, the degree of vascular invasion is becoming increasingly important. Evaluating these prognostic factors is essential for prognostic prediction and precise management of patients with FTC. Recurrence and distant metastasis of FTC are treated with radioactive iodine (RAI). However, some FTCs become refractory to RAI. Multi-tyrosine kinase inhibitors such as sorafenib and lenvatinib are utilized for treating RAI-refractory FTCs. In addition, given that renin-angiotensin system (RAS) is the most common driver gene for FTC, it is also important to develop RAS inhibitors.

Risk factors for death of follicular thyroid carcinoma: a systematic review and meta-analysis

BACKGROUND

There are conflicting reports on the factors that increase the likelihood of patients dying from follicular thyroid carcinoma (FTC). Therefore, it is critical to identify risk factors of patients with FTC. This study aimed to identify the factors that increase the risk of death of patients with FTC and help clinicians make better treatment and follow-up decisions.

METHODS

A systematic literature review was conducted in PubMed and Web of Science databases for relevant studies published before January 31, 2023. Their reference lists were also analyzed. Two reviewers extracted data and evaluated the quality of eligible studies independently. Studies on patients who had open thyroidectomy procedures with or without neck dissection were included in this review. The RevMan 5.3 software was used to analyze the data.

RESULTS

This meta-analysis included thirteen studies with a total of 2075 patients. The following variables were associated with an increased risk of death in FTC patients: age > 45 years, male, tumor diameter > 4 cm, multifocality, extrathyroidal extension (ETE), widely invasive (WI), cervical lymph node metastasis (CLNM), distant metastases (DM) and non-radical resection tumor. Lobectomy and no radioactive iodine (RAI) treatment was not associated with the death of FTC patients.

CONCLUSION

Clinicians should pay closer attention to the following significant risk factors associated with the death of FTC patients: age (> 45), male, multifocality, tumor diameter > 4 cm, ETE, WI, non-radical resection tumor, CLNM, and DM. Individualized initial treatment and close follow-up are needed FTC patients who have these risk factors.

Deep Learning-Based Differential Diagnosis of Follicular Thyroid Tumors Using Histopathological Images

Deep learning systems (DLSs) have been developed for the histopathological assessment of various types of tumors, but none are suitable for differential diagnosis between follicular thyroid carcinoma (FTC) and follicular adenoma (FA). Furthermore, whether DLSs can identify the malignant characteristics of thyroid tumors based only on random views of tumor tissue histology has not been evaluated. In this study, we developed DLSs able to differentiate between FTC and FA based on 3 types of convolutional neural network architecture: EfficientNet, VGG16, and ResNet50. The performance of all 3 DLSs was excellent (area under the receiver operating characteristic curve = 0.91 ± 0.04; F1 score = 0.82 ± 0.06). Visual explanations using gradient-weighted class activation mapping suggested that the diagnosis of both FTC and FA was largely dependent on nuclear features. The DLSs were then trained with FTC images and linked information (presence or absence of recurrence within 10 years, vascular invasion, and wide capsular invasion). The ability of the DLSs to diagnose these characteristics was then determined. The results showed that, based on the random views of histology, the DLSs could predict the risk of FTC recurrence, vascular invasion, and wide capsular invasion with a certain level of accuracy (area under the receiver operating characteristic curve = 0.67 ± 0.13, 0.62 ± 0.11, and 0.65 ± 0.09, respectively). Further improvement of our DLSs could lead to the establishment of automated differential diagnosis systems requiring only biopsy specimens.

Multi-Omics and Management of Follicular Carcinoma of the Thyroid

Follicular thyroid carcinoma (FTC) is the second most common cancer of the thyroid gland, accounting for up to 20% of all primary malignant tumors in iodine-replete areas. The diagnostic work-up, staging, risk stratification, management, and follow-up strategies in patients who have FTC are modeled after those of papillary thyroid carcinoma (PTC), even though FTC is more aggressive. FTC has a greater propensity for haematogenous metastasis than PTC. Furthermore, FTC is a phenotypically and genotypically heterogeneous disease. The diagnosis and identification of markers of an aggressive FTC depend on the expertise and thoroughness of pathologists during histopathological analysis. An untreated or metastatic FTC is likely to de-differentiate and become poorly differentiated or undifferentiated and resistant to standard treatment. While thyroid lobectomy is adequate for the treatment of selected patients who have low-risk FTC, it is not advisable for patients whose tumor is larger than 4 cm in diameter or has extensive extra-thyroidal extension. Lobectomy is also not adequate for tumors that have aggressive mutations. Although the prognosis for over 80% of PTC and FTC is good, nearly 20% of the tumors behave aggressively. The introduction of radiomics, pathomics, genomics, transcriptomics, metabolomics, and liquid biopsy have led to improvements in the understanding of tumorigenesis, progression, treatment response, and prognostication of thyroid cancer. The article reviews the challenges that are encountered during the diagnostic work-up, staging, risk stratification, management, and follow-up of patients who have FTC. How the application of multi-omics can strengthen decision-making during the management of follicular carcinoma is also discussed.

Unexpected Widespread Bone Metastases from a BRAF K601N Mutated Follicular Thyroid Carcinoma within a Previously Resected Multinodular Goiter

Follicular thyroid carcinoma (FTC) represents the second most common malignant thyroid neoplasm after papillary carcinoma (PTC). FTC is characterized by the tendency to metastasize to distant sites such as bone and lung. In the last 20 years, the understanding of the molecular pathology of thyroid tumors has greatly improved. Uncommon BRAF non-V600E mutations have been identified and are generally believed to associate with follicular patterned tumors of low malignant potential, particularly non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTPs) (i.e., non-invasive encapsulated follicular variant PTC). We here report for the first time widespread bone metastases from a BRAF K601N mutated follicular tumor.

Encapsulated Angioinvasive Follicular Thyroid Carcinoma: Prognostic Impact of the Extent of Vascular Invasion

BACKGROUND

Previous studies have reported an association between four or more foci of vascular invasion (VI) and thyroid cancer prognosis, while the current study aimed to investigate the association between extent of VI and outcome of encapsulated angioinvasive follicular thyroid carcinoma (FTC).

METHODS

The records of 303 patients with encapsulated angioinvasive FTC confirmed by surgical specimens at Ito Hospital from January 2005 to December 2014 were retrospectively reviewed. Thirteen patients had distant metastasis at diagnosis and were classified as M1.

RESULTS

Among the 290 patients with M0 encapsulated angioinvasive FTC, the 10-year disease-free survival (DFS) rate was 85.6%. Those with a VI of 1 (n = 131) or ≥ 2 (n = 159) had a 10-year DFS rate of 94.9% and 77.9% (p < 0.001), respectively, and those with a VI of 1-3 (n = 211) or ≥ 4 (n = 79) had a 10-year DFS rate of 86.3% and 83.3% (p = 0.311), respectively. Multivariate analysis identified age ≥ 55 years (p = 0.031) and VI ≥ 2 (p = 0.002) as independent negative prognostic factors for DFS. Patients with M0 encapsulated angioinvasive FTC aged ≥ 55 years and VI ≥ 2 had significantly poorer prognosis and a 10-year DFS rate of 66.4% (p < 0.001).

CONCLUSIONS

Patients with encapsulated angioinvasive FTC who had two or more foci of VI, especially patients aged ≥ 55 years, should be carefully followed-up.

Risk Factors and Prognosis for Metastatic Follicular Thyroid Cancer

BACKGROUND

Follicular thyroid cancer (FTC) is the second most common malignancy of thyroid. About 7%-23% of patients with FTC have distant metastasis. The aim of this study was to investigate the risk factors associated with distant metastasis and the impact of distant metastasis on survival in FTC patients.

METHODS

Patients with FTC were analyzed using a prospectively maintained dataset of thyroid cancer registered at a tertiary hospital in Taiwan between December 1976 and May 2020.

RESULTS

A total of 190 patients with a mean follow-up of 7.7 years were included in this study, including 29 with distant metastasis at diagnosis, 14 who developed metastasis during follow-up, and 147 without metastasis. Multivariate analysis adjusted for age, gender, tumor stage, and extrathyroidal invasion revealed old age (≥ 55 years) (adjusted odds ratio, 27.6; 95% confidence interval [CI], 8.75-86.8; P < 0.001) and extrathyroidal invasion (odds ratio, 24.1; 95% CI, 3.50-166.5; P = 0.001) were significantly associated with an increased risk of distant metastasis. Metastasis was correlated with higher cancer-specific mortality (adjusted hazard ratio, 35.5; 95% CI, 6.1-206.1; P < 0.001). In addition, patients with metastatic FTC diagnosed on initial presentation had the lowest 10-year cancer-specific survival rate (26.0%), followed by those who developed metastatic disease after initial treatment (76.6%), while patients without metastasis were all alive (100%) (P ≤ 0.002 for all comparisons).

CONCLUSIONS

Age and extrathyroidal invasion are significant risk factors for distant metastasis of FTC. Patients with metastatic FTC, especially when diagnosed on initial presentation, have dismal survival outcomes.

Development and Validation of an Ultrasonic Diagnostic Model for Differentiating Follicular Thyroid Carcinoma from Follicular Adenoma

Background

High-resolution ultrasound is the first choice for the diagnosis of thyroid nodules, but it is still difficult to distinguish between follicular thyroid carcinoma (FTC) and follicular adenoma (FA). Our research aimed to develop and validate an ultrasonic diagnostic model for differentiating FTC from FA.

Methods

This study retrospectively analyzed 196 patients who were diagnosed as FTC (n=83) and FA (n=113). LASSO regression analysis was used to screen clinical and ultrasonic features. Multivariate logistic regression analysis was used to establish the ultrasonic diagnostic model of FTC. Nomogram was used for the visualization of diagnostic models. C-index, ROC, and calibration curves analysis were used to evaluate the accuracy of the diagnostic model. Decision curve analysis (DCA) was used to evaluate the net benefits of the ultrasonic diagnostic model for FTC diagnosis under different threshold probabilities. The bootstrap method was used to verify the ultrasonic diagnostic model.

Results

After Lasso regression analysis, 10 clinical and ultrasonic features were used to construct the ultrasonic diagnostic model of FTC. The C-index and AUC of the model were 0.868 and 0.860, respectively. DCA showed that the ultrasonic model had good clinical application value. The C-index in the validation group was 0.818, which was close to the C-index in the model.

Conclusion

Ultrasonic diagnostic model constructed with 10 clinical and ultrasonic features can better distinguish FTC from FA.

Prognostic significance of vascular invasion and cell-proliferation activity in widely invasive follicular carcinoma of the thyroid

Widely invasive follicular thyroid carcinoma (wi-FTC) is regarded as having an aggressive character and a dire prognosis, but it has not been known whether all wi-FTCs have a dire prognosis. Herein we retrospectively analyzed the cases of 133 patients with wi-FTCs to determine the prognostic significance of vascular invasion and cell-proliferation activity based on the Ki-67 labeling index (LI). Of the 119 patients without distant metastasis (M0), 11 (9.2%) showed recurrence during the postoperative follow-up. In a univariate analysis, the recurrence-free survival (RFS) rates of the M0 patients with vascular invasion and those with a Ki-67 LI ≥5% were significantly poorer (p = 0.0013 and p = 0.0268, respectively) than those of the patients without vascular invasion or with a Ki-67 LI <5%. Other clinicopathological factors such as patient age, gender, tumor size, and oxyphilic tumor were not significantly related to the patients' RFS. In a multivariate analysis, positive vascular invasion independently affected the RFS (p = 0.0133), but Ki-67 >5% did not (p = 0.1348). To date, only five patients have died of their thyroid carcinoma; four cases were M1. In conclusion, although M0 wi-FTC generally has a favorable prognosis, cases with positive vascular invasion or a high Ki-67 LI are likely to recur, and careful postoperative follow-up is necessary.

Active surveillance in small cytological indeterminate thyroid nodules: a call to common sense?

PURPOSE

To describe the clinical characteristics and outcomes of patients with cytologically Bethesda IV category (B IV) thyroid nodules who opted for active surveillance.

MATERIALS AND METHODS

We prospectively evaluated 155 patients with a single thyroid nodule classified as B IV. Immediate molecular testing and/or thyroid surgery was offered, except when the patient (i) could not afford molecular testing/rejected the surgery, (ii) had a high surgical risk, (iii) had other disorders/comorbidities which needed to be addressed with higher priority, and (iv) had undetectable serum calcitonin levels, in whom active surveillance (AS) was performed.

RESULTS

From 155 patients, only two patients could afford molecular testing; 84% (n = 130) underwent immediate thyroid surgery: lobectomy was performed in only 8% (n = 10). AS was the initial management for 15% (n = 23) of the patients. The frequency of tumor enlargement was 14% (n = 3), after a median of 42 months (range, 7-72) of follow-up, without any evidence of lymph node or clinical distant metastases development. Deferred surgery was performed in 4 patients (17%) after a median of 24 months (range, 12-48) of AS. Follicular adenoma was diagnosed in three and a follicular variant of papillary thyroid carcinoma in one patient, all of them without evidence of disease after 12 months of follow-up.

CONCLUSIONS

Despite current guidelines does not support AS for indeterminate Bethesda IV nodules, our findings showed that most of these patients had excellent outcomes, in a setting where lobectomy was not the preference and the access to molecular testing was limited. Probably AS could be a valid alternative in these low-risk tumors in selected patients.

Effect of Prophylactic Central Lymph Node Dissection on Locoregional Recurrence in Patients with Papillary Thyroid Microcarcinoma

There is a consensus that central compartment lymph node dissection or modified radical lateral neck dissection should be performed in papillary thyroid microcarcinoma (PTMC) patients with lymph node metastases. Prophylactic central lymph node dissection (PCLND) in patients with clinically node-negative (cN0) PTMC to reduce locoregional recurrence (LRR) rate and improve prognosis remains controversial. The present study aimed to analyze the effect of PCLND on LRR and postoperative complications of PTMC in cN0 patients. We reviewed a cohort of patients with cN0 PTMC who underwent surgery between January 1997 and October 2019. The patients were divided into the PCLND and no lymph node dissection (NLND) groups. Kaplan-Meier curves were constructed to estimate 15-year locoregional recurrence-free survival rate of the two groups, and the difference was compared by the log-rank test. Three Cox regression models were performed to evaluate the correlation between PCLND and LRR. All patients underwent thyroidectomy, and 25 patients developed LRR; of whom, 23 underwent PCLND at initial surgery and 2 went without lymph node dissection. Cox regression analysis showed that PCLND had no effect on LRR. Postoperative hematoma and permanent recurrent laryngeal nerve injury did not occur in the NLND group, and their incidences were 0.5% and 0.3% in the PCLND group, respectively. PCLND had no significant correlation with LRR in patients with cN0 PTMC, and the absolute benefit for PTMC was small.

Outcomes for Minimally Invasive Follicular Thyroid Carcinoma in Relation to the Change in Age Stratification in the AJCC 8th Edition

BACKGROUND

Completion total thyroidectomy with radioactive iodine (RAI) therapy is not uniformly recommended for minimally invasive follicular thyroid carcinomas (MI-FTCs) without distant metastasis, but may be considered for cases with a risk factor of recurrence, such as age ≥ 45 years.

OBJECTIVE

The present study aimed to investigate the outcomes for patients with MI-FTC using a stratification age of 55 years.

METHODS

The records of 478 patients with MI-FTC confirmed by surgical specimens at Ito Hospital from January 2005 to December 2014 were retrospectively reviewed. Twenty patients had distant metastasis at diagnosis and were subsequently classified as M1.

RESULTS

Among the 478 patients with MI-FTC, univariate analysis identified that age ≥ 55 years (p = 0.002) and M1 (p < 0.001) were related to cause-specific survival. In 458 patients with M0 MI-FTC, male sex (p = 0.041), age ≥ 55 years (p = 0.001), and tumor size > 40 mm (p < 0.001) were related to poor disease-free survival (DFS) in univariate analysis. Multivariate analysis showed that age ≥ 55 years (p = 0.005) and tumor size > 40 mm (p = 0.005) were independent prognostic factors for DFS. The 10-year DFS rates of patients aged < 45 years, 45 years ≤ age < 55 years, and ≥ 55 years were 97.0%, 95.5%, and 86.4%, respectively.

CONCLUSIONS

The change in the recommended age for completion total thyroidectomy with RAI, from 45 to 55 years, seemed reasonable.

FOLLICULAR THYROID CARCINOMA - CLINICAL AND DIAGNOSTIC FINDINGS IN A 20-YEAR FOLLOW UP STUDY

Context

Follicular thyroid carcinomas (FTC) represent 6-10 % of all thyroid carcinomas; the evolution of FTC is quite controversial, partly due to frequent changes of the histopathological definition (minimally invasive-MIFTC or widely invasive carcinoma-WIFTC) and treatment strategies adjustments.

Objective

This research aims to examine the diagnostic procedure, therapeutic attitude and survival rates of patients with FTC, over a period of 16 years in the same institution, with a follow-up of at least 4 years, by analyzing correlations between histology subtype, treatments and the rate of recurrent disease.

Subjects and methods

We have studied 5891 patients with thyroid carcinomas who have undergone surgical or oncological treatment within the institution, between 1^st January 2000 - 31^st December 2015; among them we found 133 patients (2.25%) with "pure" follicular thyroid carcinoma: 114 (86%) women and 19 (14%) men, with a female-male ratio of 6:1. The age of the patients ranged from 10 to 76 years, with an average of 47.8 years. Statistical analysis was done comparing differences among groups of MIFTC and WIFTC.

Results

There was an unexpected high percentage of WIFTC and also an increased number of biochemically persistent and/or recurrent disease in patients with MIFTC. A stronger correlation was observed with the tumour dimensions, rather than with the histopathological subtype.

Conclusions

This research observed that overall survival was associated with tumour size rather than histopathological subtype and there is an important need to perform further studies to assess the effectiveness of treatment strategies.

The revised clinical practice guidelines on the management of thyroid tumors by the Japan Associations of Endocrine Surgeons: Core questions and recommendations for treatments of thyroid cancer

The Japan Associations of Endocrine Surgeons has developed the revised version of the Clinical Practice Guidelines for Thyroid Tumors. This article describes the guidelines translated into English for the 35 clinical questions relevant to the therapeutic management of thyroid cancers. The objective of the guidelines is to improve health-related outcomes in patients with thyroid tumors by enabling users to make their practice evidence-based and by minimizing any variations in clinical practice due to gaps in evidential knowledge among physicians. The guidelines give representative flow-charts on the management of papillary, follicular, medullary, and anaplastic thyroid carcinoma, along with recommendations for clinical questions by presenting evidence on the relevant outcomes including benefits, risks, and health conditions from patients' perspective. Therapeutic actions were recommended or not recommended either strongly (◎◎◎ or XXX) based on good evidence (😊)/good expert consensus (+++), or weakly (◎, ◎◎ or X, XX) based on poor evidence (😣)/poor expert consensus (+ or ++). Only 10 of the 51 recommendations given in the guidelines were supported by good evidence, whereas 35 were supported by good expert consensus. While implementing the current guidelines would be of help to achieve the objective, we need further clinical research to make our shared decision making to be more evidence-based.

Radiomics Based on Thyroid Ultrasound Can Predict Distant Metastasis of Follicular Thyroid Carcinoma

We aimed to evaluate whether radiomics analysis based on gray-scale ultrasound (US) can predict distant metastasis of follicular thyroid cancer (FTC). We retrospectively included 35 consecutive FTCs with distant metastases and 134 FTCs without distant metastasis. We extracted a total of 60 radiomics features derived from the first order, shape, gray-level cooccurrence matrix, and gray-level size zone matrix features using US imaging. A radiomics signature was generated using the least absolute shrinkage and selection operator and was used to train a support vector machine (SVM) classifier in five-fold cross-validation. The SVM classifier showed an area under the curve (AUC) of 0.90 on average on the test folds. Age, size, widely invasive histology, extrathyroidal extension, lymph node metastases on pathology, nodule-in-nodule appearance, marked hypoechogenicity, and rim calcification on the US were significantly more frequent among FTCs with distant metastasis compared to those without metastasis (p < 0.05). Radiomics signature and widely invasive histology were significantly associated with distant metastasis on multivariate analysis (p < 0.01 and p = 0.003). The classifier using the results of the multivariate analysis showed an AUC of 0.93. The radiomics signature from thyroid ultrasound is an independent biomarker for noninvasively predicting distant metastasis of FTC.

Thyroid cancer among patients with thyroid nodules in Yemen: a three-year retrospective study in a tertiary center and a specialty clinic

Background

The prevalence of thyroid cancer is increasing worldwide. No previous data are available on the prevalence of thyroid cancer in Yemen. We performed this study to determine the prevalence of thyroid cancer among patients with thyroid nodules in Yemen.

Methods

A retrospective chart review was performed for 550 patients with thyroid nodules who underwent fine needle aspiration and/or thyroid surgery at a private endocrine clinic and at an endocrine clinic in a tertiary hospital in Yemen over a 3 -year period from October 2016–2019. The prevalence of thyroid cancer; the sonographic findings, Bethesda classification, age, sex, thyroid stimulating hormone (TSH) levels of the patients; and the nodule size and number were reviewed.

Results

A total of 550 charts were reviewed [501 females (91.1%) and 49 males (8.9%)]. The thyroid cancer prevalence among the patients was 13.8% (CI = 10.9–16.7), and the mean age of the patients was 38.5 years (SD = 12.2). The TSH level and the rate of cancer were significantly related (P = 0.01), but no significant difference in the prevalence of thyroid cancer was found between females (13.4%) and males (18.4%) (P = 0.334). When correlating the rate of cancer with the ultrasound guided fine needle aspiration (UG-FNA) result, those with Bethesda system category III and IV, V and VI had malignancy rates of 20.8, 27.2, 52.4 and 69.2%, respectively. Thyroid nodules highly suspicious for malignancy on ultrasound had a 70% cancer diagnosis rate. The most common thyroid cancer was papillary cancer (71%), followed by follicular cancer (23.7%). Among those undergoing surgery, 44.2% had thyroid cancer, and 5.2% had a premalignant diagnosis.

Conclusion

Thyroid cancer has a higher prevalence in Yemen than in other middle eastern countries. Our study also reports a higher rate of follicular thyroid cancer than that in other published data, which has to be confirmed by further studies. The malignancy and premalignant diagnosis rate was ~ 50% in our patients who underwent surgery. Many centers in Yemen still do not perform FNA before thyroid surgery. It is important that other centers in the country start emphasizing the need for FNA before surgery. This will decrease the number of unnecessary surgeries and associated complications.

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.

The Difference in Thyroid Stimulating Hormone Levels between Differentiated Carcinoma and Benign Enlargement

Introduction  Papillary and follicular thyroid carcinoma are common head and neck cancers. This cancer expresses a thyroid stimulating hormone (TSH) receptor that plays a role as a cancer stimulant substance. This hormone has a diagnostic value in the management of thyroid carcinoma. Objective  The present study aimed to determine the difference in TSH levels between differentiated thyroid carcinoma and benign thyroid enlargement. Methods  The present research design was a case-control study. The subjects were patients with thyroid enlargement who underwent thyroidectomies at the Dr. Sardjito General Hospital, Yogyakarta, Indonesia. Thyroid stimulating hormone levels were measured before the thyroidectomies. The inclusion criteria for the case group were: 1) differentiated thyroid carcinoma, and 2) complete data; while the inclusion criteria for the control group were: 1) benign thyroid enlargement, and 2) complete data. The exclusion criteria for both groups were: 1) patients suffering from thyroid hormone disorders requiring therapy before thyroidectomy surgery, 2) patients receiving thyroid suppression therapy before the thyroidectomy was performed, and 3) patients suffering from severe chronic diseases such as renal insufficiency, and severe liver disease. Results  There were 40 post-thyroidectomy case group patients and 40 post-thyroidectomy control group patients. There were statistically significant differences in TSH levels between the groups with differentiated thyroid carcinoma and benign thyroid enlargement ( p  = 0.001; odds ratio [OR] = 8.42; 95% confidence interval [CI]: 3.19-36.50). Conclusion  Based on these results, it can be concluded that there were significant differences in TSH levels between the groups with differentiated thyroid carcinoma and benign thyroid enlargement.

Chest wall lymph node metastasis from follicular thyroid carcinoma: a rare case report

BACKGROUND

Distant metastases from follicular thyroid carcinoma are mainly hematogenous and are commonly observed in the lungs and bones. Other rare sites are the parotid gland, skin, brain, ovary, adrenal gland, kidney, pancreas and breast, with chest wall lymph node metastasis being even more rare.

CASE PRESENTATION

Over the past 10 years, three surgeries were performed on a 69-year-old women with a history of follicular thyroid cancer and its metastatic lesions. The patient presented with a 3-month history of masses in the left chest. She underwent detailed examination of the chest wall tumors, and surgery was then performed to resect all of the tumors. Based on the histopathology, these lymph nodes were confirmed to harbor metastatic follicular thyroid carcinoma.

CONCLUSION

This study reports the first case of follicular thyroid carcinoma metastasis to the chest wall lymph node.

The surgical dilemma of primary surgery for follicular thyroid neoplasms

Follicular thyroid carcinoma is the second most prevalent form of differentiated thyroid carcinoma, following papillary thyroid carcinoma. Preoperative diagnosis is hampered by the fact that fine-needle aspiration cytology as well as supplemental molecular analysis cannot unambiguously distinguish between follicular thyroid carcinoma and benign follicular thyroid adenoma. The 2017 WHO classification defines three histological subtypes of follicular thyroid carcinoma: minimally invasive (excellent prognosis), encapsulated angioinvasive, and widely invasive type (higher risk of recurrence and metastatic spread). The fact that definite characterization of follicular neoplasms is predominantly a postoperative histological diagnosis (core criteria: capsular, vascular and adjacent tissue invasion) translates into the challenge for the thyroid surgeon to plan preoperatively for presence of malignancy and, if required, to adapt the surgical strategy according to intraoperative (frozen section) or postoperative histological findings. Until improved tools for pre-/intraoperative diagnosis are available, the malignant potential of a follicular thyroid lesion can be assessed by stratifying the patient according to clinical risk factors (presence of metastases, advanced patient age, tumor size). A stepwise, escalating surgical approach with restricted primary resection (hemithyroidectomy) and completion surgery based on the definite histopathology is another option to solve this dilemma. The currently recommended surgical treatment strategies for FTCs as published by ATA, BTA, CAEK and ESES are discussed. There is consensus that prophylactic lymphadenectomy is not required for FTCs and that hemithyroidectomy is sufficient in low-risk FTCs (capsular invasion only) whereas thyroidectomy with postoperative radioiodine therapy is indicated in high-risk FTCs (angioinvasion; widely invasive FTC).

Prediction of follicular thyroid carcinoma associated with distant metastasis in the preoperative and postoperative model

BACKGROUND

Only clinicopathological findings are reported for predicting follicular thyroid carcinoma (FTC) associated with distant metastasis, and preoperative ultrasound (US) findings are unknown.

METHODS

Associations between distant metastases of FTC and predicting factors were evaluated by using logistic regression analysis in the preoperative and postoperative models.

RESULTS

Distant metastasis was present in 37 (11.5%) of the 321 patients with FTC. In the preoperative model, independent predictors of distant metastasis were age, marked hypoechogenicity, nodule-in-nodule appearance, and rim calcification on US. Postoperative predictors were marked hypoechogenicity, rim calcification, and widely invasive histology. Sensitivities, specificities, and the area under the curves for predicting distant metastasis were 86.5%, 80.3%, and 0.889 on preoperative status and 86.5%, 78.5%, and 0.908 on postoperative status. Although not statistically significant, all four patients with gross extrathyroidal extension had metastasis.

CONCLUSION

Age, ultrasound features, and widely invasive histology allow preoperative and postoperative prediction of FTC associated with distant metastasis.

Surgical management of follicular thyroid carcinoma in children and adolescents: A study of 30 cases

BACKGROUND/PURPOSE

The purpose of the study is to describe the anatomoclinical, diagnostic, therapeutic and prognostic aspects of pediatric follicular thyroid carcinoma (FTC) in order to choose the best therapeutic strategy.

METHODS

Our study includes patients ≤18 years old surgically treated for FTC in four Italian Pediatric Surgery Centers from January 2000 to March 2017. The collected data were compared with those of 132 patients matched for age with a histological diagnosis of papillary thyroid carcinoma (PTC) surgically treated in the same institutions during the same period and with the data of patients diagnosed with FTC found in the literature; p-values <0.05 were considered significant.

RESULTS

21 (70%) of the 30 patients with a histological diagnosis of FTC underwent hemithyroidectomy while 9 (30%) underwent total thyroidectomy. 11 (55%) out of 21 patients were subjected to a completion of thyroidectomy. All patients are alive (OS = 100%) without recurrence or relapse of the disease. Compared with PTC, FTC is significant for capsule infiltration (p < 0.0001), vascular invasion (p = 0.0014) and T-stage T3-T4 (p = 0.013). However, multifocality (p < 0.001), extrathyroid extension (p < 0.0001) and lymph node metastasis (p < 0.0001) are more evident in PTC.

CONCLUSION

The conservative approach seems to be a valid surgical treatment for pediatric patients diagnosed with MI-FTC. For patients with wide vascular invasion and/or a tumor >4 cm, especially with high after-surgery Tg rate, a completion of thyroidectomy is recommended. In patients with multifocal neoplasia, and/or tumor size ≥4 cm, and/or extrathyroid extension, and/or lymph node metastasis, and/or distant metastasis, total thyroidectomy followed by radioiodine therapy is generally indicated.

LEVELS OF EVIDENCE

II.

Preoperative sonographic features of follicular thyroid carcinoma predict biological behavior: A retrospective study

Little is known regarding biological behavior of follicular thyroid carcinomas (FTCs) according to ultrasonography features. We investigated whether there was a difference in biological behavior between benign-looking FTCs (B-FTCs) and malignant-looking FTCs (M-FTCs).A total of 55 cases of FTC between January 2000 and December 2015 were included. B-FTCs were defined as showing none of the accepted ultrasonography criteria for malignancy, and M-FTCs were defined as showing at least one of the accepted ultrasonography criteria for malignancy. Clinicopathologic factors and sonographic features were compared between B-FTCs and M-FTCs. Based on the degree of invasiveness, FTCs were divided into minimally invasive FTCs (MI-FTCs) and widely invasive FTCs (WI-FTCs) on pathology. Sonographic features were compared between MI-FTCs and WI-FTCs.Compared with the patients with B-FTCs (31/55, 56.4%), the patients with M-FTCs showed a significantly higher prevalence of WI-FTCs, central lymph node metastases, lateral lymph node metastases as well as extrathyroidal extension (P < .001, P = .012, P = .031, and P = .032, respectively). M-FTCs with more than one malignancy features on ultrasonography showed a significantly higher prevalence of extrathyroidal extension than M-FTCs with only one ultrasonography malignancy feature (P = .022). Compared with MI-FTCs (41/55, 74.5%), an irregular shape, a spiculated/microlobulated boundary, no peripheral halo ring, hypoechogenicity and microcalcification were more frequent in WI-FTCs (P < .001, P = .003, P = .002, P = .015, and P = .016, respectively).Our results demonstrated that B-FTCs had better prognostic indicators than M-FTCs. Therefore, preoperative US features can serve as a useful tool for predicting biological behavior in FTC.

Neck Ultrasound in Patients with Follicular Thyroid Carcinoma

There are limited data on the role of neck ultrasound (US) in the surveillance of patients with follicular thyroid cancer (FTC). Here, we analyze the likelihood of US to find structural disease in patients with FTC and evaluate if initial American Thyroid Association (ATA) risk stratification and the response to therapy categories [the latter based on thyroglobulin (Tg) levels] modify that likelihood. We conducted a retrospective cohort study of 32 patients with FTC in our institution. We included all patients with well-differentiated FTC who underwent total thyroidectomy and radioactive iodine (RAI) treatment without neck structural disease at the time of RAI and with Tg and US at least 6 months after RAI. After a median follow-up of 4.3 years, two patients (6.3%) had structural disease by US. None of the 18 patients with initial ATA low-risk disease had structural disease by US in contrast to higher, but not significant, frequency of 18.2% (2/11) in patients with initial ATA high-risk disease (p = 0.14). Based on Tg levels, 24/32 patients had excellent response to therapy and 8/32 had biochemical incomplete/indeterminate response. None of the patients with excellent response had structural disease by US versus 2/8 (25%) patients with biochemical incomplete/indeterminate response all of whom had other sites of structural disease (p = 0.054). Our findings suggest that neck US in FTC is unlikely to find structural disease with initial low-risk ATA or excellent response to therapy but can detect structural disease in some patients with initial ATA high-risk or incomplete/indeterminate responses to therapy.

Follicular thyroid cancer and Hürthle cell carcinoma: challenges in diagnosis, treatment, and clinical management

Follicular thyroid cancer is the second most common differentiated thyroid cancer histological type and has been overshadowed by its more common counterpart-papillary thyroid cancer-despite its unique biological behaviour and less favourable outcomes. In this Review, we comprehensively review the literature on follicular thyroid cancer to provide an evidence-based guide to the management of these tumours, to highlight the lack of evidence behind guideline recommendations, and to identify changes and challenges over the past decades in diagnosis, prognosis, and treatment. We highlight that correct identification of cancer in indeterminate cytological samples is challenging and ultrasonographic features can be misleading. Despite certain unique aspects of follicular thyroid cancer presentation and prognosis, no specific recommendations exist for follicular thyroid cancer and Hürthle cell carcinoma in evidence-based guidelines. Efforts should be made to stimulate additional research in this field.

Differentiation of the Follicular Neoplasm on the Gray-Scale US by Image Selection Subsampling along with the Marginal Outline Using Convolutional Neural Network

We conducted differentiations between thyroid follicular adenoma and carcinoma for 8-bit bitmap ultrasonography (US) images utilizing a deep-learning approach. For the data sets, we gathered small-boxed selected images adjacent to the marginal outline of nodules and applied a convolutional neural network (CNN) to have differentiation, based on a statistical aggregation, that is, a decision by majority. From the implementation of the method, introducing a newly devised, scalable, parameterized normalization treatment, we observed meaningful aspects in various experiments, collecting evidence regarding the existence of features retained on the margin of thyroid nodules, such as 89.51% of the overall differentiation accuracy for the test data, with 93.19% of accuracy for benign adenoma and 71.05% for carcinoma, from 230 benign adenoma and 77 carcinoma US images, where we used only 39 benign adenomas and 39 carcinomas to train the CNN model, and, with these extremely small training data sets and their model, we tested 191 benign adenomas and 38 carcinomas. We present numerical results including area under receiver operating characteristic (AUROC).

Metastatic Follicular Thyroid Carcinoma and the Primary Thyroid Gross Examination: Institutional Review of Cases from 1990 to 2015

The diagnosis of follicular-patterned carcinomas, including follicular thyroid carcinoma, oncocytic (Hürthle cell) carcinoma, and the encapsulated follicular variant of papillary thyroid carcinoma, requires evidence of capsular and/or vascular invasion. With minimally invasive carcinomas classified often within less than a millimeter of tissue segregating them from adenomas and non-invasive follicular thyroid neoplasms with papillary-like nuclear features, opinions vary internationally over how much of the capsule to submit in order to deem it well enough represented, considering that even if grossly entirely submitted in microcassettes, without leveling through each tissue block, the capsule is truly never entirely examined microscopically. Here, we retrospectively examine submission practices and outcomes at a single, high-volume institution over a 25-year period. Our results indicate that the vast majority of lesions with poor outcomes are those with wide invasion, and tumors lacking gross evidence of capsular perturbation rarely lead to recurrence or metastasis, an unsurprising result that should prompt re-evaluation of our grossing methods and approach to follicular-patterned tumors in a time of cost restraint, molecular diagnostics, and low biological potential of encapsulated, circumscribed neoplasia of the thyroid.

Clinical Factors Influencing the Performance of Gene Expression Classifier Testing in Indeterminate Thyroid Nodules

BACKGROUND

Molecular diagnostic testing is increasingly used in the management of indeterminate thyroid nodules. Limited data exist regarding the influence of clinical factors on gene expression classifier (GEC) test performance. This study examined the positive and negative predictive value of GEC as stratified by nodule size.

METHODS

A prospectively maintained pathology database from a single tertiary referral center was queried from 2012 to 2015 for indeterminate thyroid nodules that underwent GEC testing. Nodule size, patient demographics, Bethesda classification, and Hürthle cell-predominant nodules (HCNs) were evaluated as predictors of GEC performance.

RESULTS

Two hundred and thirty-one patients with 245 indeterminate nodules were examined. Assuming all nodules to be benign unless proven malignant on histopathology, the sensitivity and specificity of GEC testing were 95.2% and 60.1%, respectively. The malignancy rate among resected nodules was 25.3%. The positive predictive value was consistent across nodule sizes: 45.5% for nodules <1 cm, 42.9% for nodules 1-1.9 cm, 36.0% for nodules 2-2.9 cm, 54.2% for nodules 3-3.9 cm, and 50.0% for nodules ≥4 cm. The negative predictive value ranged from 93.3% to 100% and was not affected by nodule size. HCNs had a high rate of GEC suspicious results (77.4% vs. 50.5% for nodules without Hürthle cell predominance, p < 0.01), though this did not correspond to a difference in the rate of malignancy (25.8% vs. 25.3%).

CONCLUSIONS

Nodule size did not affect GEC test performance in the present cohort. GEC benign results remain reliable in large nodules. GEC suspicious nodules >3 cm carry a similar risk of malignancy compared to smaller nodules, and do not warrant more aggressive treatment. GEC testing has limited clinical utility for HCNs due to the high rate of false-positive results.