Inter-Observer Variation in the Pathologic Identification of Minimal Extrathyroidal Extension in Papillary Thyroid Carcinoma

Patterns in the Reporting of Aggressive Histologic Subtypes in Papillary Thyroid Cancer

INTRODUCTION

The tall cell, columnar, and diffuse sclerosing subtypes are aggressive histologic subtypes of papillary thyroid cancer (PTC) with increasing incidence, yet there is a wide variation in reporting. We aimed to identify and compare factors associated with the reporting of these aggressive subtypes (aPTC) to classic PTC (cPTC) and secondarily identify differences in outcomes.

METHODS

The National Cancer Database was utilized to identify cPTC and aPTC from 2004 to 2017. Patient and facility demographics and clinicopathologic variables were analyzed. Independent predictors of aPTC reporting were identified and a survival analysis was performed.

RESULTS

The majority of aPTC (67%) were reported by academic facilities. Compared to academic facilities, all other facility types were 1.4-2.0 times less likely to report aPTC (P < 0.05). Regional variation in reporting was noted, with more cases reported in the Middle Atlantic, despite there being more total facilities in the South Atlantic and East North Central regions. Compared to the Middle Atlantic, all other regions were 1.4-5 times less likely to report aPTC (P < 0.001). Patient characteristics including race and income were not associated with aPTC reporting. Compared to cPTC, aPTC had higher rates of aggressive features and worse 5-y overall survival (90.5% versus 94.5%, log rank P < 0.001).

CONCLUSIONS

Aggressive subtypes of PTC are associated with worse outcomes. Academic and other facilities in the Middle Atlantic were more likely to report aPTC. This suggests the need for further evaluation of environmental or geographic factors versus a need for increased awareness and more accurate diagnosis of these subtypes.

ATA risk stratification in papillary thyroid microcarcinoma has low positive predictive value when identifying recurrence

BACKGROUND

Rising incidence of papillary thyroid microcarcinomas (PTMC) has raised concerns for overdiagnosis. Utility of the American Thyroid Association Risk Stratification System (ATA-RSS) 2015 in predicting risk of disease recurrence in patients with PTMC was assessed.

METHODS

Electronic health records of patients who underwent total thyroidectomy were queried. ATA-RSS 2015 risk stratification was performed on those with PTMC, and validity for predicting disease recurrence was calculated.

RESULTS

With 10-year median follow up, recurrence was higher in PTMC patients with high/intermediate vs low ATA risk (33 ​% vs 4 ​%, p ​= ​0.002). Sensitivity of ATA-RSS for detecting recurrence was 60 ​%, specificity 90 ​%, PPV 33.3 ​%, NPV 96.6 ​%, and accuracy 88 ​%. When microscopic extrathyroidal extension (ETE) was excluded as an intermediate risk criterion, PPV improved to 50 ​% and accuracy improved to 92.5 ​% CONCLUSIONS: ATA-RSS 2015 predicts recurrence in PTMC with high NPV but low PPV. Exclusion of microscopic ETE improved PPV, which may help prevent overtreatment.

Radiofrequency ablation for capsular-located versus noncapsular-located papillary thyroid microcarcinoma: a propensity score matching study of 1095 patients

OBJECTIVES

To assess the safety and efficacy of radiofrequency ablation (RFA) for capsular-located papillary thyroid microcarcinoma (PTMC) in a large cohort and to compare its outcomes with those of noncapsular-located PTMC.

METHODS

We retrospectively reviewed patients who underwent RFA for solitary capsular-located and noncapsular-located low-risk PTMC (n = 1095) from June 2014 to October 2020. To balance confounding variables between capsular and noncapsular groups, we employed the 1:1 propensity score matching approach. We evaluated and compared tumor changes, disease progression, and complications in both groups. Furthermore, we analyzed the association between capsular location and disease progression using multivariable Cox regression.

RESULTS

During a mean follow-up time of 29.86 ± 16.14 months and 29.73 ± 15.69 months, no substantial difference was observed between capsular and noncapsular groups in the latest volume (0.83 ± 3.66 mm3 vs. 0.85 ± 3.67 mm3, p = 0.44) and volume reduction ratio (99.29 ± 4.04% vs. 99.43 ± 3.03%, p = 0.43), and cumulative disappearance rate (87.87% vs. 86.07%, p = 0.31). In addition, no significant differences were observed in complication incidence (1.35% vs. 1.12%, p = 0.76) and progression-free survival (p = 0.53). Based on adjusted multivariate Cox proportional hazard analysis, the association between capsular location and disease progression was nonsignificant (all p > 0.05).

CONCLUSION

This study demonstrates that the short-term outcomes of RFA for capsular-located PTMCs are comparable to those of noncapsular-located PTMCs. These findings indicate that RFA may be a viable and effective alternative for eligible patients with solitary capsular-located PTMC.

CLINICAL RELEVANCE STATEMENT

Radiofrequency ablation may serve as a safe and effective alternative treatment method for eligible patients with capsular-located and noncapsular-located papillary thyroid microcarcinoma.

KEY POINTS

• The safety and efficacy of radiofrequency ablation for capsular-located and noncapsular-located papillary thyroid microcarcinomas were comparable. • Disease progression did not differ significantly between capsular-located and noncapsular-located papillary thyroid microcarcinomas. • The incidence of complications for capsular-located papillary thyroid microcarcinoma was low.

A Data-Driven Approach to Refine Predictions of Differentiated Thyroid Cancer Outcomes: A Prospective Multicenter Study

CONTEXT

The risk stratification of patients with differentiated thyroid cancer (DTC) is crucial in clinical decision making. The most widely accepted method to assess risk of recurrent/persistent disease is described in the 2015 American Thyroid Association (ATA) guidelines. However, recent research has focused on the inclusion of novel features or questioned the relevance of currently included features.

OBJECTIVE

To develop a comprehensive data-driven model to predict persistent/recurrent disease that can capture all available features and determine the weight of predictors.

METHODS

In a prospective cohort study, using the Italian Thyroid Cancer Observatory (ITCO) database (NCT04031339), we selected consecutive cases with DTC and at least early follow-up data (n = 4773; median follow-up 26 months; interquartile range, 12-46 months) at 40 Italian clinical centers. A decision tree was built to assign a risk index to each patient. The model allowed us to investigate the impact of different variables in risk prediction.

RESULTS

By ATA risk estimation, 2492 patients (52.2%) were classified as low, 1873 (39.2%) as intermediate, and 408 as high risk. The decision tree model outperformed the ATA risk stratification system: the sensitivity of high-risk classification for structural disease increased from 37% to 49%, and the negative predictive value for low-risk patients increased by 3%. Feature importance was estimated. Several variables not included in the ATA system significantly impacted the prediction of disease persistence/recurrence: age, body mass index, tumor size, sex, family history of thyroid cancer, surgical approach, presurgical cytology, and circumstances of the diagnosis.

CONCLUSION

Current risk stratification systems may be complemented by the inclusion of other variables in order to improve the prediction of treatment response. A complete dataset allows for more precise patient clustering.

Predicting Extrathyroidal Extension in Papillary Thyroid Carcinoma Using a Clinical-Radiomics Nomogram Based on B-Mode and Contrast-Enhanced Ultrasound

Papillary thyroid carcinoma (PTC) is the most common pathological type of thyroid cancer. PTC patients with extrathyroidal extension (ETE) are associated with poor prognoses. The preoperative accurate prediction of ETE is crucial for helping the surgeon decide on the surgical plan. This study aimed to establish a novel clinical-radiomics nomogram based on B-mode ultrasound (BMUS) and contrast-enhanced ultrasound (CEUS) for the prediction of ETE in PTC. A total of 216 patients with PTC between January 2018 and June 2020 were collected and divided into the training set (n = 152) and the validation set (n = 64). The least absolute shrinkage and selection operator (LASSO) algorithm was applied for radiomics feature selection. Univariate analysis was performed to find clinical risk factors for predicting ETE. The BMUS Radscore, CEUS Radscore, clinical model, and clinical-radiomics model were established using multivariate backward stepwise logistic regression (LR) based on BMUS radiomics features, CEUS radiomics features, clinical risk factors, and the combination of those features, respectively. The diagnostic efficacy of the models was assessed using receiver operating characteristic (ROC) curves and the DeLong test. The model with the best performance was then selected to develop a nomogram. The results show that the clinical-radiomics model, which is constructed by age, CEUS-reported ETE, BMUS Radscore, and CEUS Radscore, showed the best diagnostic efficiency in both the training set (AUC = 0.843) and validation set (AUC = 0.792). Moreover, a clinical-radiomics nomogram was established for easier clinical practices. The Hosmer-Lemeshow test and the calibration curves demonstrated satisfactory calibration. The decision curve analysis (DCA) showed that the clinical-radiomics nomogram had substantial clinical benefits. The clinical-radiomics nomogram constructed from the dual-modal ultrasound can be exploited as a promising tool for the pre-operative prediction of ETE in PTC.

Papillary Carcinoma in Thyroglossal Duct Cyst and Thyroid Gland with Hashimoto

The ectopic thyroid gland is a rare condition. In most cases, ectopic thyroid tissue is the only functioning thyroid tissue, but it may rarely be associated with a normal thyroid gland. Ectopic thyroid carcinoma within a thyroglossal duct cyst is a very rare entity, with controversial individual approaches. This encouraged us to present the case of a 31-year- old woman, with papillary thyroid carcinoma in the thyroid gland and in the thyroid ectopic tissue within the thyroglossal duct. After suspicion of thyroid malignancy in the ultrasonography of the neck, FNA-biopsy was performed on the thyroid nodule and the thyroglossal duct cyst. Since the pathological exam revealed a papillary carcinoma in the eutopic and ectopic thyroid tissues, the Sistrunk procedure and total thyroidectomy were done, followed by radioiodine ablation.

A Retrospective Cohort Study with Validation of Predictors of Differentiated Thyroid Cancer Outcomes

Background: The goal of radioactive iodine (RAI) in differentiated thyroid cancer (DTC) is to treat metastasis and reduce recurrence risk. International guidelines provide broad risk stratification to aid treatment decisions, but a more nuanced approach to individualize care is warranted. We developed a predictive risk model for DTC. Methods: We performed a retrospective multivariable analysis of 899 patients who received RAI after thyroidectomy at a quaternary center in Australia between 2008 and 2016. Collected data included age, gender, histology, stimulated thyroglobulin (sTg), and 8th American Joint Committee Cancer (AJCC) staging. The ATA Modified Initial Risk (ATA) was calculated retrospectively. Recurrence was defined as clinically significant progression requiring either surgical intervention or administration of a second activity of RAI. Synchronous metastasis was defined as distant metastasis (i.e., outside of the neck) that was present at the time of diagnosis on structural imaging or initial post-iodine treatment scan. The features significantly associated with synchronous metastasis or recurrence were employed in the generation of a predictive risk model. A separate cohort of 393 patients who received RAI in 2017-2021 was used for validation. Results: On multivariate analysis, sTg ≥10 μg/L, extrathyroidal extension (ETE) and lymph node involvement predicted recurrence. Independent of ATA, patients with sTg ≥10 μg/L had a shorter disease-free survival (DFS) than those with sTg <10 μg/L (p < 0.001). The ETE stratified by four histological categories was significantly associated with worse DFS (p < 0.001). In a subset of patients, the presence of thyroglobulin antibody (TgAb) did not influence recurrence in patients with sTg <10 μg/L. On multivariate analysis, widespread ETE, sTg ≥10 μg/L, multifocal papillary thyroid cancer and follicular thyroid cancer were positively associated with synchronous metastasis. A predictive risk model was developed to estimate synchronous metastasis/recurrence risk and validated successfully in the second cohort. Conclusions: Our novel predictive risk model modifies and extends ATA stratification by including sTg and ETE, which we found to be independent predictors of both recurrence and synchronous metastasis in DTC.

Adverse Histological Features of Differentiated Thyroid Cancer Are Commonly Found in Autopsy Studies: Implications for Treatment Guidelines

Background: While the popularity of lobectomy for differentiated thyroid cancer (DTC) has increased since the 2015 ATA (American Thyroid Association) guidelines, recent studies reported that adverse histological features (minimal extrathyroidal extension [mETE], multifocality, vascular invasion, and lymph node [LN] metastases) may be found in 30-60% of lobectomy specimens, questioning the validity of this approach. Aim: To assess the prevalence adverse histological features in occult DTC detected in autopsy studies. Methods: Meta-analysis of autopsy studies of the thyroid in subjects without known history of thyroid cancer. Results: Twenty-nine studies including 8750 subjects fulfilled the inclusion criteria, with incidentally discovered DTC in 740 autopsies (8.5%). Age was reported in 17 studies, with a median age of 61 years (range 41-68 years). Multifocality was reported in 27 studies with a calculated event rate of 28.2% ([CI 23.1-33.8], I² = 46.3%), with bilateral involvement in 18% [CI 12.6-25.1]. mETE was reported in 5 studies, with an event rate of 24.5% ([CI 9.3-50.7], I² = 88.5%), and the presence of LN metastases were reported in 13 studies with an event rate of 11% ([CI 6.1-19.1], I² = 69.5%). Vascular invasion was reported in seven studies with an event rate of 16% ([CI 4-47], I² = 86.8%). Of 25 studies with whole body autopsies (722 subjects), 3 cases of distant metastases were reported, of which 2 had fatal metastatic disease (where thyroid origin was not diagnosed before death), and 1 had occult disease. Conclusions: Adverse histological features including mETE, LN metastases, multifocality, and vascular invasion are common in occult DTC. When minimal in size, these adverse histological features do not seem to be markers of aggressive disease and may not be an indication for completion thyroidectomy or radioiodine therapy.

Microscopic Extrathyroidal Extension Results in Increased Rate of Tumor Recurrence and Is an Independent Predictor of Patient’s Outcome in Middle Eastern Papillary Thyroid Carcinoma

Background

Papillary Thyroid Cancer (PTC) is the most common endocrine malignancy, with recurrence rate as high as 30%. A great deal of controversy surrounds the significance of microscopic extrathyroidal extension (m-ETE) as a prognostic factor. The most recent edition (8^th) of American Joint Committee on Cancer (AJCC) staging system has removed m-ETE from the definition of pT3, which suggests that m-ETE may lack prognostic impact in PTC patients. Moreover, data about m-ETE prevalence and clinical impact on Middle Eastern PTC remains unknown. We therefore investigate the prevalence of m-ETE and its clinico-pathological correlation and prognostic impact in Middle Eastern PTC. We also compared the AJCC 7^th and 8^th staging systems and their prognostic performance.

Methods

PTCs from 1430 consecutive adult (> 18 years) patients from single tertiary care hospital were included in this study. A retrospective analysis of PTC patients’ survival and recurrence were compared between AJCC 8^th and AJCC 7^th staging systems using Proportion of Variation Explained (PVE) and Harrell’s C-index.

Results

Median follow up of the study cohort was 9.3 years. 31.2% (446/1430) of patients had m-ETE. In the overall cohort, m-ETE was associated with multiple adverse features such as older age (p < 0.0001), male sex (p = 0.0245), tall cell variant (p < 0.0001), bilateral tumors (p < 0.0001), multifocality (p < 0.0001), lymphovascular invasion (p < 0.0001), lymph node metastasis (p < 0.0001), distant metastasis (p = 0.0166), tumor recurrence (p < 0.0001), radioactive iodine refractoriness (p < 0.0001), BRAF mutation (p < 0.0001) and reduced recurrence-free survival (RFS; HR = 1.75; 95% CI = 1.30 – 2.35; p < 0.0001) irrespective of tumor size. Of the 611 patients with T3 disease based on AJCC 7^th edition, 359 (58.8%) were down-staged in AJCC 8^th edition classification. Overall, the prognostic performance of AJCC 8^th edition was inferior to AJCC 7^th on the basis of lower PVE (3.04% vs. 3.73%) and lower C-index (0.40 vs. 0.48).

Conclusions

In Middle Eastern PTC, m-ETE is significantly associated with compromised survival and acts as an independent predictor of RFS. Given these findings, m-ETE should be included in the thyroid cancer treatment guidelines.

Trends in Diagnosis of Noninvasive Follicular Thyroid Neoplasm With Papillarylike Nuclear Features and Total Thyroidectomies for Patients With Papillary Thyroid Neoplasms

Importance

Increasing detection of early-stage papillary thyroid neoplasms without improvements in mortality has prompted development of strategies to prevent or mitigate overtreatment.

Objective

To determine adoption rates of 2 recent strategies developed to limit overtreatment of low-risk thyroid cancers: (1) a new classification, noninvasive follicular thyroid neoplasm with papillarylike nuclear features (NIFTP), and (2) hemithyroidectomy for selected papillary thyroid carcinomas (PTCs) up to 4 cm in size.

Design, Setting, and Participants

This is a cross-sectional analysis of 3368 pathology records of 2 cohorts of patients from 18 hospitals in 6 countries during 2 time periods (2015 and 2019). Participating hospitals were included from the US (n = 12), Canada (n = 2), Denmark (n = 1), South Korea (n = 1), South Africa (n = 1), and India (n = 1). The records of the first 100 patients per institution for each year who underwent thyroid-directed surgery (hemithyroidectomy, total thyroidectomy, or completion thyroidectomy) were reviewed.

Main Outcomes and Measures

Frequency of diagnosis of NIFTP, PTCs, and thyroidectomies during the study period.

Results

Of the 790 papillary thyroid neoplasms captured in the 2019 cohort, 38 (4.8%) were diagnosed as NIFTP. Diagnosis of NIFTP was observed in the US, South Africa, and India. There was minimal difference in the total proportion of PTCs in the 2015 cohort compared with the 2019 cohort (778 [47.1%] vs 752 [44.5%]; difference, 2.6% [95% CI, -16.9% to 22.1%]). The proportion of PTCs eligible for hemithyroidectomy but treated with total thyroidectomy in the 2 cohorts demonstrated a decreasing trend from 2015 to 2019 (341 of 453 [75.3%] vs 253 of 434 [58.3%]; difference, 17.0% [95% CI, -1.2% to 35.2%]).

Conclusions and Relevance

Results of this cohort study showed that the 2 mitigation strategies for preventing overtreatment of early-stage thyroid cancer have had mixed success. The diagnosis of NIFTP has only been applied to a small proportion of thyroid neoplasms compared with expected rates. However, more patients eligible for hemithyroidectomy received it in 2019 compared with 2015, showing some success with this deescalation strategy.

Dual Encoder Attention U-net for Nuclei Segmentation

Nuclei segmentation in whole slide images (WSIs) stained with Hematoxylin and Eosin (H&E) dye, is a key step in computational pathology which aims to automate the laborious process of manual counting and segmentation. Nuclei segmentation is a challenging problem that involves challenges such as touching nuclei resolution, small-sized nuclei, size, and shape variations. With the advent of deep learning, convolution neural networks (CNNs) have shown a powerful ability to extract effective representations from microscopic H&E images. We propose a novel dual encoder Attention U-net (DEAU) deep learning architecture and pseudo hard attention gating mechanism, to enhance the attention to target instances. We added a new secondary encoder to the attention U-net to capture the best attention for a given input. Since H captures nuclei information, we propose a stain-separated H channel as input to the secondary encoder. The role of the secondary encoder is to transform attention prior to different spatial resolutions while learning significant attention information. The proposed DEAU performance was evaluated on three publicly available H&E data sets for nuclei segmentation from different research groups. Experimental results show that our approach outperforms other attention-based approaches for nuclei segmentation.

Papillary Thyroid Carcinoma in Ukraine After Chernobyl and in Japan After Fukushima: Different Histopathological Scenarios

Background: A significant increase in the incidence of papillary thyroid carcinoma (PTC) in subjects exposed to radiation at a young age is a well-documented health consequence of the Chernobyl accident. The ongoing Thyroid Ultrasound Examination (TUE) program in children and adolescents of Fukushima Prefecture in Japan also indicated a high prevalence of PTC although its attribution to radiation exposure is a subject of debate. The objective of this study was to perform histopathological analysis of tumor architecture and invasive properties in (i) radiogenic post-Chernobyl and sporadic PTCs from Ukraine, and (ii) PTCs in patients from Fukushima and other Prefectures of Japan of comparable age groups. Methods: The Ukrainian radiogenic PTCs included 245 PTCs from patients who resided in three highly ¹³¹I-contaminated regions and 165 sporadic PTCs diagnosed in residents of the same regions who were born after the accident and therefore not exposed to radioiodine. The Japanese series included 115 PTCs detected during the preliminary and the first full-scale surveys of the TUE in Fukushima and 223 PTCs from patients resident in other Prefectures. All of the subjects were included in the main statistical analysis. Three additional analyses were performed limiting the subjects to children, adolescents, and adults. Results: Ukrainian radiogenic PTC was characterized by the higher frequency of tumors with a dominant solid-trabecular growth pattern and higher invasiveness, more frequent extrathyroidal extension, lymphatic/vascular invasion, regional and distant metastases when compared with sporadic Ukrainian PTC. The integrative "invasiveness score," based on five cancer characteristics, was also higher in the radiogenic group. The differences were most pronounced in children. In contrast, no significant differences in tumor morphology or invasiveness were observed between the two Japanese groups or the three age subgroups. The only statistically significant findings were the higher proportion of male patients, smaller mean tumor size, and higher frequency of T1b tumors in the Fukushima group. Conclusions: The difference in morphological features that indicate biological behavior of PTC between the radiation-related and sporadic groups from Ukraine, together with the lack of such in the two groups from Japan, strongly suggest a nonradiogenic etiology of PTC from Fukushima and other Prefectures.

Stability of diagnostic rate in a cohort of 38,813 colorectal polyp specimens and implications for histomorphology and statistical process control

This work sought to quantify pathologists’ diagnostic bias over time in their evaluation of colorectal polyps to assess how this may impact the utility of statistical process control (SPC). All colorectal polyp specimens(CRPS) for 2011–2017 in a region were categorized using a validated free text string matching algorithm. Pathologist diagnostic rates (PDRs) for high grade dysplasia (HGD), tubular adenoma (TA_ad), villous morphology (TVA + VA), sessile serrated adenoma (SSA) and hyperplastic polyp (HP), were assessed (1) for each pathologist in yearly intervals with control charts (CCs), and (2) with a generalized linear model (GLM). The study included 64,115 CRPS. Fifteen pathologists each interpreted > 150 CRPS/year in all years and together diagnosed 38,813. The number of pathologists (of 15) with zero or one (p < 0.05) outlier in seven years, compared to their overall PDR, was 13, 9, 9, 5 and 9 for HGD, TVA + VA, TA_ad, HP and SSA respectively. The GLM confirmed, for the subset where pathologists/endoscopists saw > 600 CRPS each(total 52,760 CRPS), that pathologist, endoscopist, anatomical location and year were all strongly correlated (all p < 0.0001) with the diagnosis. The moderate PDR stability over time supports the hypothesis that diagnostic rates are amendable to calibration via SPC and outcome data.

Analysis of risk factors and prognosis in differentiated thyroid cancer with focus on minimal extrathyroidal extension

AIMS

In contrast to all prior AJCC/TNM classifications for differentiated thyroid cancer (DTC) the 8th edition does not take minimal extrathyroidal extension (M-ETE) into consideration for local tumor staging. We therefore aimed to retrospectively assess the specific impact of M-ETE on the outcome of M-ETE patients treated in our clinic.

METHODS

DTC patients with M-ETE and a follow-up time of ≥ 5 years were included and matched with an identical number of patients without M-ETE, but with equal histopathological tumor subtype and size. The frequency of initially metastatic disease among groups was compared using Fisher's exact test, the recurrence rate by virtue of log-rank test. Fisher's exact test and multivariate analysis were used to account for the presence of confounding risk factors.

RESULTS

One hundred sixty patients (80 matching pairs) were eligible. With other confounding risk factors being equal, the prevalence of N1-/M1-disease at initial diagnosis was comparable among groups (M-ETE: 42.5 %; no M-ETE: 32.5 %; p = 0.25). No differences with regard to the recurrence rate were shown. However, M-ETE patients were treated with external beam radiation therapy more often (16.3 % vs. 1.3 %; p = 0.004) and received higher median cumulative activities of ¹³¹I (10.0 vs. 8.0 GBq; p < 0.001).

DISCUSSION

Although having played a pivotal role for local tumor staging of DTC for decades M-ETE did not increase the risk for metastases at initial diagnosis and the recurrence rate in our cohort. Patients with M-ETE had undergone intensified treatment, which entails a possible confounding factor that warrants further investigation in randomized controlled trials.

Ultrasound of Thyroid Nodules and the Thyroid Imaging Reporting and Data System

Benign or malignant thyroid nodules are common in adults. Fine needle aspiration biopsy is the gold standard for diagnosis. Most thyroid nodules are benign. Ultrasound imaging is the optimal noninvasive imaging modality to determine which nodules demonstrate malignant features. The American College of Radiology Thyroid Imaging Reporting and Data System committee published a standardized approach to classifying nodules on ultrasound. The ultrasound features in this system are categorized as benign, minimally suspicious, moderately suspicious, or highly suspicious for malignancy. Applying the Thyroid Imaging Reporting and Data System results in a meaningful decrease in the number of thyroid nodules biopsied.

Minimal extrathyroid extension in papillary micro carcinoma of the thyroid is an independent risk factor for relapse through lymph node and distant metastases

Aims: Minimal extrathyroid extension (mETE) is no longer considered in the new 8th edition of the AJCC/UICC staging system. Therefore, papillary thyroid microcarcinoma with mETE previously staged as pT3 will now be staged as pT1a and most likely not receive adjuvant radioiodine therapy. However, it remains unclear if mETE is associated with higher aggressiveness in papillary thyroid microcarcinoma. Therefore, the aim of this study was to investigate if mETE is associated with higher risk of lymph node or distant metastases. Methods: 721 patients with thyroid papillary microcarcinoma presenting at our department for postoperative counseling from 05/1983 to 8/2012 were included in this retrospective analysis (median follow-up time 9.30 years). The impact of mETE on the presence of lymph node metastases at thyroidectomy and relapse through lymph node and distant metastases was assessed by logistic regression and Fine-Gray model analyses. Results: 10.7% (n = 77) of patients had mETE. mETE was an independent risk factor for lymph node metastases at thyroidectomy with an adjusted odds ratio of 4.33 (95%CI: 2.02-9.60, p<0.001) in multivariable analysis. Patients with mETE had significantly more relapses through lymph node (over 5 years: 13.1% vs. 1.25%; P < 0.001) and distant metastases (over 5 years: 7.8% vs. 1.1%; P < 0.001) compared to patients without mETE. mETE was an independent risk factor for relapse through lymph node and distant metastases in multivariable analysis (hazard ratio: 7.78, 95%CI: 2.87-21.16, p< 0.001 and 4.09, 95%CI: 1.25-13.36, P = 0.020). Conclusion: mETE is a statistically significant and independent risk factor for relapse through lymph node and distant metastases in papillary microcarcinoma. Therefore, future studies should evaluate, if patients with mETE and microcarcinoma might benefit from intensified surveillance and therapy.

Real-World Performance of the American Thyroid Association Risk Estimates in Predicting 1-Year Differentiated Thyroid Cancer Outcomes: A Prospective Multicenter Study of 2000 Patients

Background: One of the most widely used risk stratification systems for estimating individual patients' risk of persistent or recurrent differentiated thyroid cancer (DTC) is the American Thyroid Association (ATA) guidelines. The 2015 ATA version, which has increased the number of patients considered at low or intermediate risk, has been validated in several retrospective, single-center studies. The aims of this study were to evaluate the real-world performance of the 2015 ATA risk stratification system in predicting the response to treatment 12 months after the initial treatment and to determine the extent to which this performance is affected by the treatment center in which it is used. Methods: A prospective cohort of DTC patients collected by the Italian Thyroid Cancer Observatory web-based database was analyzed. We reviewed all records present in the database and selected consecutive cases that satisfied inclusion criteria: (i) histological diagnosis of DTC, with the exclusion of noninvasive follicular thyroid neoplasm with papillary-like nuclear features; (ii) complete data of the initial treatment and pathological features; and (iii) results of 1-year follow-up visit (6-18 months after the initial treatment), including all data needed to classify the estimated response to treatment. Results: The final cohort was composed of 2071 patients from 40 centers. The ATA risk of persistent/recurrent disease was classified as low in 1109 patients (53.6%), intermediate in 796 (38.4%), and high in 166 (8.0%). Structural incomplete responses were documented in only 86 (4.2%) patients: 1.5% in the low-risk, 5.7% in the intermediate-risk, and 14.5% in the high-risk group. The baseline ATA risk class proved to be a significant predictor of structural persistent disease, both for intermediate-risk (odds ratio [OR] 4.67; 95% confidence interval [CI] 2.59-8.43) and high-risk groups (OR 16.48; CI 7.87-34.5). Individual center did not significantly influence the prediction of the 1-year disease status. Conclusions: The ATA risk stratification system is a reliable predictor of short-term outcomes in patients with DTC in real-world clinical settings characterized by center heterogeneity in terms of size, location, level of care, local management strategies, and resource availability.

Oncocytic Papillary Thyroid Carcinoma and Oncocytic Poorly Differentiated Thyroid Carcinoma: Clinical Features, Uptake, and Response to Radioactive Iodine Therapy, and Outcome

OBJECTIVE

The main objective of this study was to review the clinicopathologic characteristics and outcome of patients with oncocytic papillary thyroid carcinoma (PTC) and oncocytic poorly differentiated thyroid carcinoma (PDTC). The secondary objective was to evaluate the prevalence and outcomes of RAI use in this population.

METHODS

Patients with oncocytic PTC and PDTC who were treated at a quaternary cancer centre between 2002 and 2017 were retrospectively identified from an institutional database. All patients had an expert pathology review to ensure consistent reporting and definition. The cumulative incidence function was used to analyse locoregional failure (LRF) and distant metastasis (DM) rates. Univariable analysis (UVA) was used to assess clinical predictors of outcome.

RESULTS

In total, 263 patients were included (PTC [n=218], PDTC [n=45]) with a median follow up of 4.4 years (range: 0 = 26.7 years). Patients with oncocytic PTC had a 5/10-year incidence of LRF and DM, respectively, of 2.7%/5.6% and 3.4%/4.5%. On UVA, there was an increased risk of DM in PTC tumors with widely invasive growth (HR 17.1; p<0.001), extra-thyroidal extension (HR 24.95; p<0.001), angioinvasion (HR 32.58; p=0.002), focal dedifferentiation (HR 19.57, p<0.001), and focal hobnail cell change (HR 8.67, p=0.042). There was additionally an increased risk of DM seen in male PTC patients (HR 5.5, p=0.03).The use of RAI was more common in patients with larger tumors, angioinvasion, and widely invasive disease. RAI was also used in the management of DM and 43% of patients with oncocytic PTC had RAI-avid metastatic disease. Patients with oncocytic PDTC had a higher rate of 5/10-year incidence of LRF and DM (21.4%/45.4%; 11.4%/40.4%, respectively). Patients with extra-thyroidal extension had an increased risk of DM (HR 5.52, p=0.023) as did those with angioinvasion. Of the patients with oncocytic PDTC who received RAI for the treatment of DM, 40% had RAI-avid disease.

CONCLUSION

We present a large homogenous cohort of patients with oncocytic PTC and PDTC, with consistent pathologic reporting and definition. Patients with oncocytic PTC have excellent clinical outcomes and similar risk factors for recurrence as their non-oncocytic counterparts (angioinvasion, large tumor size, extra-thyroidal extension, and focal dedifferentiation). Compared with oncocytic PTCs, the adverse biology of oncocytic PDTCs is supported with increased frequency of DM and lower uptake of RAI.

Data set for reporting carcinoma of the thyroid: recommendations from the International Collaboration on Cancer Reporting

Thyroid cancer therapy is increasingly tailored to patients' risk of recurrence and death, placing renewed importance on pathologic parameters. The International Collaboration on Cancer Reporting (ICCR), an organization promoting evidence-based, internationally agreed-upon standardized pathology data sets, is the ideal conduit for the development of a pathology reporting protocol aimed at improving the care of patients with thyroid carcinomas. An international expert panel reviewed each element of thyroid pathology reporting. Recommendations were made based on the most recent literature and expert opinion.The data set uses the most recent World Health Organization (WHO) classification for the purpose of a more clinically and prognostically relevant nomenclature. One example is the restriction of the term minimally invasive follicular carcinoma to tumors with capsular invasion only. It reinforces the already established criteria for blood vessel invasion adopted by the most recent WHO classification and Armed Forces Institute of Pathology fascicle. It emphasizes the importance of the extent of blood vessel invasion and extrathyroid extension to better stratify patients for appropriate therapy. It is the first data set that requires pathologists to use the more recently recognized prognostically powerful parameters of mitotic activity and tumor necrosis. It highlights the importance of assessing nodal disease volume in predicting the risk of recurrence.The ICCR thyroid data set provides the tools to generate a report that will guide patient treatment in a more rational manner aiming to prevent the undertreatment of threatening malignancies and spare patients with indolent tumors the morbidity of unnecessary therapy. We recommend its routine use internationally for reporting thyroid carcinoma histology.

Histopathologic Assessment of Capsular Invasion in Follicular Thyroid Neoplasms-an Observer Variation Study

The assessment of capsular invasion is an essential but challenging step in the diagnosis of encapsulated follicular thyroid neoplasms. Therefore, interobserver agreement in the assessment of capsular invasion in these tumors was investigated among 11 thyroid pathologists by using virtual slides of 20 cases in which the original diagnosis considered the differential diagnosis of definite capsular invasion versus questionable capsular invasion. The assessment of capsular invasion was divided into three categories: (1) non-invasive, (2) questionable invasive, and (3) clear-cut invasive. The interobserver agreements for clear-cut invasive and non-invasive categories were fair (Kappa value = 0.578 and 0.404, respectively), whereas agreement for the questionable invasion was poor (Kappa value = 0.186). Disagreements in the assessment of invasion resulted in variable final pathological diagnoses. For example, the agreement for a diagnosis of malignancy was only fair (Kappa value = 0.545). Moreover, pathologists did not have a uniform approach for rendering a final diagnosis in cases with questionable capsular invasion, though nine of 11 pathologists did use the follicular tumor of uncertain malignant potential diagnosis as proposed by the World Health Organization classification of endocrine organs published in 2017. In conclusion, this study revealed considerable interobserver variation in the evaluation of capsular invasion, especially in follicular neoplasms with questionable invasion.

Isthmic Papillary Thyroid Carcinoma Presents a Unique Pattern of Central Lymph Node Metastasis

Purpose

Treatment protocols for occult central lymph node metastasis (LNM) associated with papillary thyroid cancer (PTC) located in the isthmus are debatable. We aimed to analyze the pattern of occult central LNM in isthmic PTC, including risk factors for bilateral paratracheal LNM.

Patients and Methods

Consecutive patients with PTC were recruited to this study. All patients underwent total thyroidectomy and prophylactic bilateral central neck dissection. The clinicopathologic features and distribution of central LNM were compared between the two groups, and risk factors for bilateral paratracheal LNM were analyzed.

Results

A total of 174 patients with PTC were enrolled in this study, of whom 87 patients had isthmic PTC (study group) and 87 patients had lobe-originating PTC (control group). The two groups had comparable demographics and tumor features. There were higher frequencies of pretracheal LNM (P =0.001) and bilateral paratracheal LNM (P = 0.002) in the isthmic PTC group. Bilateral paratracheal LNM was significantly associated with age <55 years (P = 0.037), capsular invasion (P = 0.034), tumor location (isthmus) (P < 0.001), BRAF gene mutation (P = 0.013), and pretracheal LNM (P < 0.001). Isthmus location (odds ratio [OR]: 4.116, 95% confidence interval [CI]: 1.264–13.433, P = 0.019) and pretracheal LNM (OR: 3.422, 95% CI: 1.214–9.642, P = 0.020) were independent risk factors for bilateral paratracheal LNM.

Conclusion

Because of its unique anatomic location, isthmic PTC differs from PTC in the lobe with respect to pretracheal and bilateral paratracheal LNM, even in patients of comparable age, sex, tumor size, extrathyroidal extension, BRAF mutation, and pathologic TNM staging. The isthmus location was found to be an independent risk factor for bilateral paratracheal LNM. This information may contribute to the development of an appropriate surgical protocol for isthmic PTC.

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.

Invasion in thyroid cancer: Controversies and best practices

Invasion is a key feature of malignancy and an important element in the classification, risk-stratification, and staging of thyroid cancers. However, the histopathologic criteria for tumor capsular invasion, angioinvasion, and extrathyroidal extension (ETE) have varied among pathologists, both in practice as well as in studies assessing the clinical significance of these findings. In this review, we provide historic context for the controversies surrounding the definition of invasion in thyroid neoplasms and highlight recent efforts to standardize how pathologists report capsular invasion, angioinvasion, and ETE. We offer practical suggestions for distinguishing invasion from its mimics and provide an algorithmic approach for classifying thyroid tumors based on integration of tumor invasiveness, nuclear atypia, and architectural pattern.

Risk of Mortality between Untreated and Treated Papillary Thyroid Cancer: A Matched Cohort Analysis

OBJECTIVES

To examine the association between treatment status and mortality risk among patients with papillary thyroid cancer (PTC).

METHODS

We identified 3,679 adults with PTC. Thirty-one untreated patients were matched to 155 treated patients. Hazards ratios (HR) and 95% confidence intervals (CIs) were calculated to estimate all-cause and disease-specific mortality. A low-risk subgroup was analyzed for differences in all-cause mortality.

RESULTS

The adjusted HRs (95% CIs) for all-cause mortality at 5 and 10 years were 4.2 (1.7-10.3) and 4.1 (1.9-9.4) and for disease- specific mortality were 14.1 (3.4-59.3) and 10.2 (2.9-36.4), respectively, for untreated versus treated patients. The adjusted HRs (95% CIs) for all- cause mortality was 0.7 (0.1-6.4) for low-risk untreated versus matched treated patients.

CONCLUSIONS

Compared to treated patients, untreated PTC patients were at higher risk of death while low-risk untreated PTC patients had comparable rate of metastasis and no increased risk of all-cause mortality. Level of evidence: 3.

Prognostic Parameters in Differentiated Thyroid Carcinomas

Differentiated thyroid carcinomas make up most thyroid malignancies. The AJCC staging system and the ATA risk prediction system are the best predictors of mortality and recurrence, respectively. Key factors to be identified and reported by pathologists are reviewed in this article and include: (1) aggressive histologic variants of papillary thyroid carcinoma (including tall cell, columnar cell, and hobnail variants); (2) presence of gross extrathyroidal extension (into skeletal muscle or adjacent organs); (3) angioinvasion (including number of foci); (4) number, anatomic level, and size of lymph node metastases; (4) extranodal extension; (5) genetics (especially BRAF V600E or TERT promoter mutation).

Proposal for an extended pTNM classification of thyroid carcinoma : Commentary on deficits of the 8th edition of the TNM classification

In the 8th edition of the TNM classification of thyroid carcinomas, which was introduced in 2017, carcinomas with minimal extrathyroidal extension are no longer mentioned, which might cause problems. These tumors were explicitly categorized in previous TNM classifications (5-7th editions). Studies on the prognostic relevance of minimal extrathyroidal extension have shown conflicting results. Moreover, the vast majority of these studies retrospectively analyzed only subgroups of thyroid carcinomas (e.g. differentiated thyroid carcinoma, papillary thyroid carcinoma). The proposed subcategorization of the current TNM classification (8th edition) ensures the continuity of the parameter minimal extrathyroidal extension within the TNM categorization of thyroid carcinomas and also offers the possibility to prospectively analyze in a standardized manner the potential biological relevance of minimal extrathyroidal extension in relation to tumor categories (T/pT category).

Critical Prognostic Parameters in the Anatomic Pathology Reporting of Differentiated Follicular Cell-Derived Thyroid Carcinoma

In the past decades, pathology reporting on thyroid carcinoma has evolved from a narrative approach to structured synoptic reports. Many histologic variables are present in the current synoptic reports that are crucial elements for initial risk stratification and clinical management. In this review, we compare and summarize the key prognostic pathologic characteristics utilized by the most influential clinical and pathologic guidelines from the American Thyroid Association (ATA), the National Comprehensive Cancer Network (NCCN), the current World Health Organization (WHO) classification of endocrine tumors (fourth edition), the current American Joint Committee on Cancer (AJCC) staging system (eighth edition), the College of American Pathologists (CAP) protocol, and the International Collaboration on Cancer Reporting (ICCR) dataset. The aim is to provide a comprehensive review focused on the definitions and prognostic impacts of these crucial pathologic parameters.

Interobserver Variability in the Histopathologic Assessment of Extrathyroidal Extension of Well Differentiated Thyroid Carcinoma Supports the New American Joint Committee on Cancer Eighth Edition Criteria for Tumor Staging

Background: Extrathyroidal extension (ETE) by papillary and follicular thyroid carcinoma can be associated with increased risk of tumor recurrence and mortality. In the seventh edition of its Cancer Staging Manual, the American Joint Committee on Cancer (AJCC) defined minimal ETE as the involvement of skeletal muscle (i.e., strap muscles) or perithyroidal soft tissue. The eighth edition of the AJCC Cancer Staging Manual has changed the criteria so that only grossly evident (macroscopic) ETE involving strap muscles (not microscopic ETE involving perithyroidal soft tissue) affects tumor staging. Summary: Concordance of identifying microscopic ETE (as well as extranodal extension by carcinoma metastatic to lymph nodes) was previously evaluated among 11 expert endocrine pathologists. The overall agreement rate was slight when rendering a diagnosis of ETE. Concordance was highest when pathologists assessed the spatial relationship of carcinoma to skeletal muscle. This article discusses the significance of these findings. It also reviews relevant anatomic and developmental considerations related to the boundaries of the thyroid. Conclusions: The results of the concordance study provide additional rationale supporting stringent criteria for diagnosing ETE, as proposed by the eighth edition of the AJCC Cancer Staging Manual. It is expected that these rigid morphologic criteria will potentially reduce interobserver variability and enhance consistency in the diagnosis and staging of thyroid carcinoma.

Predicting recurrence of papillary thyroid cancer using the eighth edition of the AJCC/UICC staging system

BACKGROUND

The AJCC/UICC classification is widely used for predicting survival in papillary thyroid cancer (PTC), but has not been evaluated as a predictor of recurrence. The hypothesis of this study was that the eighth edition of the AJCC system can be used in this novel way.

METHODS

All patients in the study underwent surgery for PTC at a high-volume endocrine surgery centre in France between 1985 and 2015. The seventh and eighth editions of the AJCC/UICC staging system for PTC were employed to predict recurrence and disease-specific survival using the Kaplan-Meier and log rank tests.

RESULTS

Among 4124 patients (79·7 per cent female), median age was 50 (i.q.r. 38-60) years; 3906 patients (94·7 per cent) underwent total thyroidectomy, with lymph node dissection in 2495 (60·5 per cent). The eighth edition of the AJCC/UICC staging system placed 91·8, 7·1, 0·4 and 0·7 per cent of patients in stages I-IV respectively. After reclassifying patients from the seventh to the eighth AJCC/UICC edition, the disease was downstaged in 23·8 per cent. Over a median follow-up of 7 years, 260 patients (6·4 per cent) developed recurrent disease, including 5·2 per cent of patients with stage I, 19·6 per cent with stage II, 59 per cent with stage III and 50 per cent with stage IV disease, according to the eighth edition. The eighth edition was a better predictor of recurrence than the seventh edition.

CONCLUSION

The eighth edition of the AJCC/UICC staging system appears to be a novel tool for predicting PTC recurrence, which is a meaningful outcome for this indolent disease. The eighth edition can be used to risk-stratify patients, keeping in mind that other molecular and pathological predictive factors must be integrated into the assessment of recurrence risk.

Identification of Hürthle cell cancers: solving a clinical challenge with genomic sequencing and a trio of machine learning algorithms

BACKGROUND

Identification of Hürthle cell cancers by non-operative fine-needle aspiration biopsy (FNAB) of thyroid nodules is challenging. Resultingly, non-cancerous Hürthle lesions were conventionally distinguished from Hürthle cell cancers by histopathological examination of tissue following surgical resection. Reliance on histopathological evaluation requires patients to undergo surgery to obtain a diagnosis despite most being non-cancerous. It is highly desirable to avoid surgery and to provide accurate classification of benignity versus malignancy from FNAB preoperatively. In our first-generation algorithm, Gene Expression Classifier (GEC), we achieved this goal by using machine learning (ML) on gene expression features. The classifier is sensitive, but not specific due in part to the presence of non-neoplastic benign Hürthle cells in many FNAB.

RESULTS

We sought to overcome this low-specificity limitation by expanding the feature set for ML using next-generation whole transcriptome RNA sequencing and called the improved algorithm the Genomic Sequencing Classifier (GSC). The Hürthle identification leverages mitochondrial expression and we developed novel feature extraction mechanisms to measure chromosomal and genomic level loss-of-heterozygosity (LOH) for the algorithm. Additionally, we developed a multi-layered system of cascading classifiers to sequentially triage Hürthle cell-containing FNAB, including: 1. presence of Hürthle cells, 2. presence of neoplastic Hürthle cells, and 3. presence of benign Hürthle cells. The final Hürthle cell Index utilizes 1048 nuclear and mitochondrial genes; and Hürthle cell Neoplasm Index leverages LOH features as well as 2041 genes. Both indices are Support Vector Machine (SVM) based. The third classifier, the GSC Benign/Suspicious classifier, utilizes 1115 core genes and is an ensemble classifier incorporating 12 individual models.

CONCLUSIONS

The accurate algorithmic depiction of this complex biological system among Hürthle subtypes results in a dramatic improvement of classification performance; specificity among Hürthle cell neoplasms increases from 11.8% with the GEC to 58.8% with the GSC, while maintaining the same sensitivity of 89%.

Histopathological analysis of papillary thyroid carcinoma detected during ultrasound screening examinations in Fukushima

Thyroid ultrasound screening of young residents in Fukushima Prefecture, Japan, showed a high detection rate of papillary thyroid carcinoma (PTC). Detailed morphological analysis of these tumors was not presented to date. This study sets out to evaluate changes in histopathological and invasive characteristics of Fukushima PTC with time after the nuclear accident of March 2011 in all available cases and in different age subgroups. Histological specimens of 115 PTCs from patients aged 18 years or younger at the time of the Fukushima Dai‐ichi Nuclear Power Plant accident, who underwent surgical resection at Fukushima Medical University during 2012‐2016, were reviewed. Patients were divided into those treated during the first 4 years after the accident (n = 78, shorter‐onset) or later (n = 37, longer‐onset). The whole group and 3 age subgroups: children (aged less than 15 years), adolescents (aged from 15 to less than 19 years), and young adults (aged from 19 years) at surgery were analyzed. No statistically significant time‐related changes in tumor structure or invasiveness were found in the whole group or in age‐matched subgroups. Statistically significant age‐related downtrend was observed for intrathyroid spread in the whole group of patients. The absence of temporal changes in tumor morphological characteristics and tumor invasiveness strongly suggests common etiology of the shorter‐ and longer‐onset Fukushima PTCs, which are unlikely related to the effect of exposure to very low doses of radiation.

Crucial parameters in thyroid carcinoma reporting - challenges, controversies and clinical implications

In the modern era, a pathology report of thyroid carcinoma requires the inclusion of numerous prognostically relevant histopathological features, e.g. the presence and extent of vascular and capsular invasion, extrathyroidal extension, the surgical margin status and the characteristics of nodal metastasis. These pathological features are crucial components of the initial risk stratification to determine the need for completion thyroidectomy and/or postoperative radioactive iodine ablation therapy. The current review aims to summarise the diagnostic criteria, the controversies, the prognostic impacts and the challenges of these pathological characteristics, focusing specifically on the parameters that are incorporated into the American Joint Committee on Cancer (AJCC) staging system, the College of American Pathologists (CAP) reporting template, the American Thyroid Association (ATA) and the National Comprehensive Cancer Network (NCCN) guidelines.

Effect of Tumor Size and Minimal Extrathyroidal Extension in Patients with Differentiated Thyroid Cancer

INTRODUCTION

Risk-stratified treatment strategies have become a focus in the treatment of differentiated thyroid cancer (DTC). In the 2015 American Thyroid Association treatment guidelines, adjuvant treatment with radioactive iodine (RAI) is considered in the presence of minimal extrathyroidal extension (mETE). This study aimed to investigate the prognostic significance of mETE and tumor size in patients with DTC.

METHODS

A retrospective review was undertaken of 2323 consecutive patients treated surgically for T1-T3 (defined per seventh edition of the American Joint Committee on Cancer staging criteria) and M0 DTC from 2000 to 2015 at The University of Texas MD Anderson Cancer Center. Patients were divided into four groups according to the size of the tumor (≤4 cm vs. >4 cm) and the presence of mETE. Predictors of disease-free survival (DFS), disease-specific survival, locoregional failure (LRF), and distant metastatic failure (DMF) were compared using the log-rank test and Cox's proportional hazards models.

RESULTS

There were only seven DTC-related deaths, limiting the clinical significance of the analysis, especially of overall and disease-specific survival. Following multivariate analysis, patients with tumors >4 cm did worse than patients with tumors ≤4 cm with respect to DFS (group 3 [>4 cm without mETE] adjusted hazard ratio (HR_adj) = 2.1 [confidence interval (CI) 1.1-3.8]; group 4 [>4 cm with mETE] HR_adj = 2.9 [CI 1.6-5.1]). However, patients did not differ according to DFS, regardless of the presence of mETE within each size category (group 2 [≤4 cm with mETE] vs. group 1 [≤4 cm without mETE] HR_adj = 1.3 [CI 0.9-1.8]; group 4 [>4 cm without mETE] vs. group 3 [>4 cm with mETE] HR_adj = 1.0 [CI 0.5-2.3]). For LRF and DMF, size but not mETE was also an independent risk factor.

CONCLUSION

Tumor size, but not the presence of mETE, was an independent predictor of DFS, LRF, and DMF in DTC.

Papillary thyroid microcarcinoma: characteristics at presentation, and evaluation of clinical and histological features associated with a worse prognosis in a Latin American cohort

Objective We aimed to describe the presentation of papillary microcarcinoma (PTMC) and identify the clinical and histological features associated with persistence/recurrence in a Latin American cohort. Subjects and methods Retrospective study of PTMC patients who underwent total thyroidectomy, with or without radioactive iodine (RAI), and who were followed for at least 2 years. Risk of recurrence was estimated with ATA 2009 and 2015 classifications, and risk of mortality with 7th and 8th AJCC/TNM systems. Clinical data obtained during follow-up were used to detect structural and biochemical persistence/recurrence. Results We included 209 patients, predominantly female (90%), 44.5 ± 12.6 years old, 183 (88%) received RAI (90.4 ± 44.2 mCi), followed-up for a median of 4.4 years (range 2.0-7.8). The 7th and 8th AJCC/TNM system classified 89% and 95.2% of the patients as stage I, respectively. ATA 2009 and ATA 2015 classified 70.8% and 78.5% of the patients as low risk, respectively. Fifteen (7%) patients had persistence/recurrence during follow-up. In multivariate analysis, only lymph node metastasis was associated with persistence/recurrence (coefficient beta 4.0, p = 0.016; 95% CI 1.3-12.9). There were no PTMC related deaths. Conclusions Our series found no mortality and low rate of persistence/recurrence associated with PTMC. Lymph node metastasis was the only feature associated with recurrence in multivariate analysis. The updated ATA 2015 and 8th AJCC/TNM systems classified more PTMCs than previous classifications as low risk of recurrence and mortality, respectively.

Impact of Minimal Extra-Thyroid Extension in Differentiated Thyroid Cancer: Systematic Review and Meta-analysis

BACKGROUND

Minimal extra-thyroid extension (mETE) in differentiated thyroid cancer (DTC) patients was defined as an intermediate risk feature in the 2015 American Thyroid Association guidelines. However, controversy persists as several studies suggested mETE has little effect on disease outcome.

OBJECTIVE

To assess the impact of mETE on DTC patients' outcome.

METHODS

Meta-analysis of controlled trials comparing DTC patients with and without mETE.

DATA EXTRACTION AND SYNTHESIS

Thirteen retrospective studies including 23,816 patients were included, with a median follow-up of 86 months. mETE in patients without lymph node involvement (N0 disease) was associated with increased risk of recurrence (7 studies, OR 1.73, 95%CI 1.03-2.92). The absolute risk of recurrence was 2.2% in patients without extension and 3.5% in patients with mETE (p=0.04). In studies including patients with and without lymph-node involvement (N1/N0 disease), mETE resulted in a significantly higher risk of recurrence (8 studies, OR 1.82, 95%CI 1.14-2.91). The absolute risk of recurrence was 6.2% in patients without extension and 7% in patients with mETE (p=0.01). In patients with micro-papillary carcinoma (<1cm) the impact of mETE was non-significant (OR 2.40, 95%CI 0.95-6.03). Minimal ETE had no impact on disease-related mortality (8 studies, OR 0.5, 95%CI 0.11-2.21).

CONCLUSION

mETE increases risk of recurrence in DTC patients. However, the absolute increase in risk is small, and in patients with N0 disease the risk is within the low-risk of recurrence category at 3.5%. Minimal ETE has no impact on disease-related mortality, and should not change tumor stage.

[Proposal for an extended pTNM classification of thyroid carcinoma : Commentary on deficits of the 8th edition of the TNM classification (German version)]

In the 8th edition of the TNM classification of thyroid carcinomas, which was introduced in 2017, carcinomas with minimal extrathyroidal extension are no longer mentioned, which might cause problems. These tumors were explicitly categorized in previous TNM classifications (5-7th editions). Studies on the prognostic relevance of minimal extrathyroidal extension have shown conflicting results. Moreover, the vast majority of these studies retrospectively analyzed only subgroups of thyroid carcinomas (e.g. differentiated thyroid carcinoma, papillary thyroid carcinoma). The proposed subcategorization of the current TNM classification (8th edition) ensures the continuity of the parameter minimal extrathyroidal extension within the TNM categorization of thyroid carcinomas and also offers the possibility to prospectively analyze in a standardized manner the potential biological relevance of minimal extrathyroidal extension in relation to tumor categories (T/pT category).

Pathologic Reporting of Tall-Cell Variant of Papillary Thyroid Cancer: Have We Reached a Consensus?

BACKGROUND

Tall-cell variant (TCV) is widely believed to be a more aggressive subtype of papillary thyroid carcinoma (PTC). Despite the significance of TCV with respect to risk stratification and therapeutic decision making, its diagnosis is subject to inter-observer variability. This study aimed to determine the level of agreement among expert pathologists in the identification and reporting of TCV.

METHODS

Seventeen surgical resections for thyroid cancer containing the diagnostic term "tall cell" in their pathology reports and 22 cases diagnosed as classical PTC were selected. Cases were digitalized, and 14 expert pathologists reviewed the scanned slides blinded to the original interpretation. Each pathologist designated each case as TCV or not and answered multiple questions about diagnostic histopathologic features of TCV.

RESULTS

The overall strength of agreement for identifying TCV was fair (Fleiss kappa 0.34), and the proportion of observed agreement was 0.70. Of 22 cases originally diagnosed as PTC classical variant, 15 (68%) were reclassified as TCV by at least one expert pathologist. It was noted that four different definitions for TCV were used by the participants based on various combinations of cell height to width (H:W) ratio and the percentage of tumor cells showing that specific ratio. All pathologists agreed that the diagnosis of TCV does not rely solely on a specific H:W ratio.

CONCLUSIONS

Pathologic reporting of TCV varies among pathologists. This disagreement is a result of the lack of unanimous diagnostic criteria and variation in individual pathologists' interpretations. These discrepancies lead to over- and under-diagnosis of TCV, which has significant implications in patient management. It is imperative to understand this variability in diagnosis TCV as it relates to risk stratification and interpretation of clinical studies related to this histologic subtype of PTC. Further studies are needed to reach consensus on the diagnostic criteria of TCV.

Dynamic risk stratification in the follow-up of thyroid cancer: what is still to be discovered in 2017?

The adequate risk stratification in thyroid carcinoma is crucial to avoid on one hand the overtreatment of low-risk and on the other hand the undertreatment of high-risk patients. The question how to properly assess the risk of relapse has been discussed during recent years and resulted in a substantial change in our approach to risk stratification in differentiated thyroid cancer, proposed by the newest ATA guidelines. First initial risk stratification, based on histopathological data is carried out just after primary surgery. It should be emphasized, that a high quality of histopathological report is crucial for proper risk stratification. Next, during the follow-up, patients are restratified considering their response to treatment applied and classified to one of the following categories: excellent response, biochemical incomplete response, structural incomplete or indeterminate response. This new approach is called dynamic risk stratification as, in contrary to the previous rigid evaluation performed at diagnosis, reflects a real-time prognosis and thereby substantially influences and personalizes disease management. In this review, we raise some unresolved questions, among them the lack of prospective studies, fulfilling evidence-based criteria, necessary to validate this model of risk stratification. We also provided some data concerning the use of dynamic risk stratification in medullary thyroid cancer, not yet reflected in ATA guidelines. In conclusion, dynamic risk stratification allows for better prediction of the risk of recurrence in thyroid carcinoma, what has been demonstrated in numerous retrospective analyses. However, the validation of this approach in prospective studies seems to be our task for near future.

Comparative histopathological analysis of sporadic pediatric papillary thyroid carcinoma from Japan and Ukraine

This study set out to compare structural and invasive characteristics of sporadic papillary thyroid carcinoma (PTC) in age-matched groups of children and adolescents of Japan and Ukraine to provide detailed histopathological analysis of tumors from different geographical areas with different iodine intake. A total of 348 (160 Japanese and 188 Ukrainian) PTCs from patients without radiation history were analyzed initially as a combined pediatric group and then subdivided into childhood (aged ≤14 years) and adolescent (aged from 15 to ≤18 years) age series. On multivariate comparison, the Japanese pediatric PTC was characterized by a higher sex ratio (p=1.504E-4), and a higher frequency of microcarcinoma (p=0.039), papillary dominant growth pattern (p=0.024), focal oxyphilic cell metaplasia (p=7.644E-6), intrathyroid spread (p=0.010), lymphatic/vascular invasion (p=0.01) and regional lymph node metastases (p=3.540E-6). In the Ukrainian group, multifocal (p=0.004) and non-encapsulated tumors with the solid-trabecular growth pattern (p=0.05) were more frequent. Childhood Japanese PTCs differed from Ukrainian PTCs by more pronounced invasive properties such as lymphatic/vascular invasion and nodal disease, but did not differ by the dominant growth pattern. In adolescents, the differences were detected not only for lymph node metastases, but also for a higher frequency of the papillary dominant pattern in Japanese PTC. Overall, significantly higher frequencies of oxyphilic cell metaplasia and more pronounced invasive features observed in the Japanese PTC in both age-matched series represent the major differences between the tumors from two geographical areas.

Evolution of the histologic classification of thyroid neoplasms and its impact on clinical management

The vast majority of low grade follicular cell derived thyroid carcinomas follows an indolent clinical course and is associated with very low mortality. Risk stratification using multiple clinical and pathologic characteristics has become the standard of care to guide appropriate management and avoid overtreatment. Over the past few decades, the field of thyroid pathology has witnessed several major changes that significantly impacted upon patients' care. These are: 1) The reclassification of non-invasive encapsulated follicular variant of papillary thyroid carcinoma as noninvasive follicular thyroid neoplasm with papillary-like nuclear features; 2) the diagnosis of Hurthle cell carcinoma based on the presence of capsular and vascular invasion; 3) a detailed definition of poorly differentiated thyroid carcinoma, taking into consideration mitosis and necrosis; and 4) the emphasis on a detailed pathologic analysis such as the extent of vascular invasion and extrathyroidal extension. This review describes these histological concepts and details the history, rationale, and clinical impacts of such changes. These shifts in the classification and characterization of thyroid carcinoma provided a platform supporting therapy de-escalation. In addition several lessons were learned from these changes especially from the misclassification of the non-invasive encapsulated follicular variant of papillary thyroid carcinoma. We hope that the lessons learned will help better classify tumors in the future whether arising in the thyroid or other organs.

ACR Thyroid Imaging, Reporting and Data System (TI-RADS): White Paper of the ACR TI-RADS Committee

classification that is widely used in breast imaging, their authors chose to apply the acronym TI-RADS, for Thyroid Imaging, Reporting and Data System. In 2012, the ACR convened committees to (1) provide recommendations for reporting incidental thyroid nodules, (2) develop a set of standard terms (lexicon) for ultrasound reporting, and (3) propose a TI-RADS on the basis of the lexicon. The committees published the results of the first two efforts in 2015. In this article, the authors present the ACR TI-RADS Committee's recommendations, which provide guidance regarding management of thyroid nodules on the basis of their ultrasound appearance. The authors also describe the committee's future directions.

Thyroglossal Duct Cyst Carcinomas: A Clinicopathologic Series of 22 Cases with Staging Recommendations

Carcinomas arising from thyroglossal duct remnant cysts (TGDCs) are rare, without well-defined management and staging criteria. All TGDCs (n = 685) diagnosed between 2005 and 2015 were retrospectively reviewed, with 22 carcinomas identified (3.2 % incidence). Twenty-two patients (17 females, 5 males), aged 12-64 years (mean 39.9 years; median 39 years) were identified. An anterior, superior midline neck mass was the presenting symptom in all patients. A cancer diagnosis [all papillary thyroid carcinoma (PTC)] was made after the Sistrunk procedure (SP), with a Bethesda Category V or VI classification preoperatively by fine needle aspiration in 5 of 12 cases tested. A SP was performed in all patients, with total thyroidectomy concurrently (n = 4) or subsequently (n = 12). A selected neck dissection was performed in 5 patients, with metastases found in 3. Of the patients who had a thyroidectomy, synchronous PTC was identified in 6 (thus, 6 of 22 patients had synchronous thyroid gland primaries). This supports an origin from extra-thyroidal remnants (cyst origin) rather than metastatic tumor from a thyroid gland primary. Follow-up radioactive iodine therapy was performed in 13 patients. Metastatic disease to local lymph nodes 57 months after presentation was seen in 1 patient, with all others alive and disease free (mean 3.8 years; range 0.4-10.8 years). The TGDCs ranged from 0.8 to 5 cm (mean 2.3 cm), while the PTCs ranged from 0.1 to 3.8 cm (mean 1.4 cm). All of the tumors were classical PTC, showing a sclerotic and infiltrative pattern, with a capsule present in 11. Lymphovascular invasion was detected in 11; margins were positive in 6. Using currently defined criteria, the patients were separated into AJCC stage group I (n = 21) or II (n = 1). However, if extension into the adipose tissue (n = 11), skeletal muscle (n = 10), or perineural/perivascular tissues (n = 10) were used to stage the patients, interpreted to represent the equivalent of "extrathyroidal extension" (n = 13) as defined for thyroid gland primaries, there would be 15 group I and 7 group III cases. All seven group III patients were ≥45 years. Three of four patients with lymph node metastasis also showed soft tissue extension. In conclusion, TGDC carcinomas (TGDCCa) are uncommon, with all classical PTC. For "microcarcinomas" (≤1 cm), conservative management can be used for patients <45 years (i.e., Sistrunk procedure only); for >1 cm tumors, and due to the high incidence of concurrent papillary carcinoma and higher stage at presentation in older patients, completion thyroidectomy is recommended for patients ≥45 years. Thus, even though a good prognosis can be expected for PTC developing in TGDCs, staging is advocated to more appropriately match therapeutic interventions.