Clinical impact of microscopic extrathyroidal extension in patients with papillary thyroid microcarcinoma treated with hemithyroidectomy

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.

Subcentimetric Papillary Thyroid Carcinoma: Does the Diagnosis Kind Impact Prognosis?

INTRODUCTION

Subcentimetric papillary thyroid carcinoma (SPTC) (papillary thyroid carcinoma with less than 10 mm in size) usually presents an excellent prognosis, with few aggressive reported cases. Given the globally increased incidence of SPTC, physicians are struggling with the need to identify prognostic factors to stratify SPTC. The aim was to compare clinicopathological variables and prognosis between clinically and incidentally diagnosed SPTC. Materials and methodsː This is a retrospective observational study on patients with SPTC who underwent thyroidectomy between 2002 and 2015. Two groups were considered: G1 (n=60 (61.9%)), clinical diagnosis (Bethesda III-VI cytology in the thyroid tumor/in cervical lymphadenopathies) and G2 (n=37 (38.1%)), incidental diagnosis (thyroidectomy for benign thyroid pathology). The histological material was reviewed, and molecular analysis of the BRAF, RAS, and TERT promoter (TERTp) genes was performed. Resultsː Ninety-seven individuals were included, 60 (61.9%) of which were from G1, with a predominance of female sex (n=83 (85.6%)). Individuals of G1 were younger (53.0±14.2 versus 59.3±13.9 years; p=0.035), were more frequently treated with 131-iodine (39.2% versus 13.4%; p=0.007), had the largest diameter (8 (p25-p75: 7-9) versus 5 (p25-p75: 4-6.5) mm; p<0.001), and higher frequency of minimal extracapsular invasion (45% versus 24.3%; p=0.041). Increased tumor size was the only independent predictor of a clinical diagnosis (p<0.001). Conclusionsː Clinically and incidentally diagnosed SPTC showed excellent medium- to long-term prognosis. A larger SPTC was more likely a driver of clinical detection than a marker of tumor aggressiveness, but caution should be taken as contradictory data persists.

Causal inference between aggressive extrathyroidal extension and survival in papillary thyroid cancer: a propensity score matching and weighting analysis

Background

Extrathyroidal extension is a major risk factor for poor prognosis in papillary thyroid cancer. However, the effect of different degrees of extrathyroidal extension on prognosis remains controversial. We performed a retrospective study to elucidate how the extent of extrathyroidal extension in papillary thyroid cancer affected the clinical prognosis of patients and its covariates.

Methods

The study included 108,426 patients with papillary thyroid cancer. We categorized the extent of extension into none, capsule, strap muscles, and other organs. Three causal inference methods for retrospective studies, namely, inverse probability of treatment weighting, standardized mortality ratio weighting, and propensity score matching analysis, were used to minimize potential selection bias. Kaplan-Meier analysis and univariate Cox regression analyses were applied to analyze the precise effect of ETE on survival in papillary thyroid cancer patients.

Results

In the Kaplan-Meier survival analysis, only extrathyroidal extension into or beyond the strap muscles was statistically significant for both overall survival (OS) and thyroid cancer-specific survival (TCSS). In univariate Cox regression analyses before and after matching or weighting based on causal inference, extrathyroidal extension into soft tissues or other organs is a high-risk factor for both overall survival and thyroid cancer-specific survival. Sensitivity analysis revealed that lower overall survival was observed in patients with older age (≥55) and larger tumor size (>2 cm) of papillary thyroid cancer with extrathyroidal extension into or beyond the strap muscles.

Conclusions

Our study indicates that extrathyroidal extension into soft tissues or other organs is a high-risk factor in all papillary thyroid cancer. Even though invasion into the strap muscles did not seem to be a marker for poor prognosis, it still impaired the overall survival of patients with older age (≥55 years old) or larger tumor size (>2 cm). Further investigation is needed to confirm our results and to clarify further risk factors independent of extrathyroidal extension.

Minimal extrathyroidal extension is associated with lymph node metastasis in single papillary thyroid microcarcinoma: a retrospective analysis of 814 patients

Background

Extrathyroidal extension (ETE) is considered a major prognostic factor in papillary thyroid carcinoma (PTC). Patients with gross ETE are at increased risk of recurrence and mortality. The importance of minimal ETE still remains controversial, especially in patients with papillary thyroid microcarcinoma (PTMC). The purpose of this study was to evaluate the association between ETE and lymph node (LN) metastasis in single PTMC.

Methods

A retrospective analysis was performed of 1994 patients underwent thyroidectomy for PTC between 2012 and 2016 in a single institution. Patients with combined thyroid carcinoma of other types and those who underwent completion thyroidectomy were excluded. After further exclusion of PTC larger than 1 cm and multifocal tumors, 814 patients with single PTMC were included in the study.

Results

72.9% patients had no ETE, 25.1% minimal ETE, and 2.1% gross ETE. ETE was associated with lymphatic invasion, perineural invasion, and vascular invasion. Patients with minimal and gross ETE were also more likely to have LN metastasis, including lateral neck metastasis, compared to those without ETE. In univariate analysis, LN metastasis was associated with male gender, conventional PTC, lymphatic invasion, perineural invasion, and ETE. In multivariate analysis, male gender (OR = 1.987; 95% CI 1.369–2.884), lymphatic invasion (OR = 4.389; 95% CI 1.522–12.658), perineural invasion (OR = 6.545; 95% CI 1.262–33.948), and minimal ETE (OR = 1.852; 95% CI 1.298–2.643) were found to be independent risk factors of LN metastasis.

Conclusions

Minimal ETE is associated with LN metastasis in single PTMC, compared to no ETE. Minimal ETE should be considered in the management of patients with single PTMC, whether surgical or during active surveillance.

Is Gross Extrathyroidal Extension to Strap Muscles (T3b) Only a Risk Factor for Recurrence in Papillary Thyroid Carcinoma? A Propensity Score Matching Study

Simple Summary

In papillary thyroid carcinoma (PTC), staging classification of gross and minimal extrathyroidal extension (ETE) has been recently modified in the eighth edition of the American Joint Commission on Cancer/Union for International Cancer Control (AJCC/UICC) TNM staging system. In this study, we compared the clinicopathological characteristics and recurrence rates between minimal and gross ETE. No significant differences in the recurrence and disease-free survival rates were found between the two groups. Whether gross ETE invading strap muscles (T3b) only could be a risk factor for recurrence in PTC remains questionable.

Abstract

The presence of extrathyroidal extension (ETE) is associated with locoregional recurrence and distant metastases in papillary thyroid carcinoma (PTC). This study was designed to compare the recurrence risk between minimal ETE (mETE) and gross ETE (gETE) in patients with PTC using propensity score matching. In this study, 4452 patients with PTC who underwent thyroid surgery in a single center were retrospectively analyzed, and clinicopathological characteristics were compared according to the ETE status. Disease-free survival (DFS) and recurrence risk were compared between mETE and gETE after propensity score matching. The mean follow-up duration was 122.7 ± 22.5 months. In multivariate analysis, both mETE and gETE were not associated with recurrence risk before propensity score matching (p = 0.154 and p = 0.072, respectively). After propensity score matching, no significant difference in recurrence rates was observed between the two groups (p = 0.668). DFS of the gETE group did not significantly differ from that of the mETE group (log-rank p = 0.531). This study revealed that both mETE and gETE are not independent risk factors for the risk of recurrence in PTC. Our findings suggest that gETE invading strap muscles only might not be associated with worse oncological outcomes in PTC.

2022 ETA Consensus Statement: What are the indications for post-surgical radioiodine therapy in differentiated thyroid cancer?

Modern use of post-operative radioactive iodine (RAI) treatment for differentiated thyroid cancer (DTC) should be implemented in line with patients' risk stratification. Although beneficial effects of radioiodine are undisputed in high-risk patients, controversy remains in intermediate-risk and some low-risk patients. Since the last consensus on post-surgical use of RAI in DTC patients, new retrospective data and results of prospective randomized trials have been published, which have allowed the development of a new European Thyroid Association (ETA) statement for the indications of post-surgical RAI therapy in DTC. Questions about which patients are candidates for RAI therapy, which activities of RAI can be used, and which modalities of pre-treatment patient preparation should be used are addressed in the present guidelines.

Position paper from the Japan Thyroid Association task force on the management of low-risk papillary thyroid microcarcinoma (T1aN0M0) in adults

The incidence of thyroid carcinoma has been increasing worldwide. This is interpreted as an increase in the incidental detection of papillary thyroid microcarcinomas (PTMCs). However, mortality has not changed, suggesting overdiagnosis and overtreatment. Prospective clinical trials of active surveillance for low-risk PTMC (T1aN0M0) have been conducted in two Japanese institutions since the 1990s. Based on the favorable outcomes of these trials, active surveillance has been gradually adopted worldwide. A task force on the management of PTMC in adults organized by the Japan Thyroid Association therefore conducted a systematic review and has produced the present position paper based on the scientific evidence concerning active surveillance. This paper indicates evidence for the increased incidence of PTMC, favorable surgical outcomes for low-risk PTMC, recommended criteria for diagnosis using fine needle aspiration cytology, and evaluation of lymph node metastasis (LNM), extrathyroidal extension (ETE) and distant metastasis. Active surveillance has also been reported with a low incidence of disease progression and no subsequent recurrence or adverse events on survival if conversion surgery was performed at a slightly advanced stage. Active surveillance is a safe and valid strategy for PTMC, because it might preserve physical quality of life and reduce 10-year medical costs. However, some points should be noted when performing active surveillance. Immediate surgery is needed for PTMC showing high-risk features, such as clinical LNM, ETE or distant metastasis. Active surveillance should be performed under an appropriate medical team and should be continued for life.

Is There a Difference Between Minimal and Gross Extension into the Strap Muscles for the Risk of Recurrence in Papillary Thyroid Carcinomas?

Background: The morbidity of papillary thyroid carcinoma (PTC) is primarily related to locoregional recurrences and distant metastases. The definition of minimal extrathyroidal extension (mETE) has been recently revised. The presence of mETE does not impact mortality and is generally not considered to be a predictor for the risk of recurrence. This study aimed at comparing the risk of recurrence and the response to therapy of PTC with mETE and gross extrathyroidal extension (ETE) into the strap muscles (gETE) with low- and intermediate-risk PTC without ETE (low risk w/o ETE and intermediate risk w/o ETE, respectively) to further characterize the impact of ETE on outcomes. Methods: A total of 596 PTCs were analyzed according to the degree of ETE as well as other predictors of recurrence. Four groups of patients were compared, low risk w/o ETE (n = 251), intermediate risk w/o ETE (n = 89), mETE (n = 191), and gETE (n = 65), to determine the risk of recurrence and the response to treatment. Cox proportional hazards models were used to investigate associations between groups and disease-free survival (DFS). Results: The risk of recurrence was 3% in low risk w/o ETE PTC, 14% in intermediate risk w/o ETE, 14% in mETE, and 25% in gETE. The recurrence risk was increased by the presence of ETE (odds ratio [OR] = 2.86, 95% confidence interval [CI] 1.36-5.85, p = 0.005) and lymph node metastases (OR = 2.44 [95% CI 1.25-4.76], p = 0.009). Patients with low-risk carcinomas w/o ETE experienced longer DFS than those with mETE (hazard ratio = 0.08 [95% CI 0.02-0.28], p < 0.001), but no significant difference was observed between intermediate risk w/o ETE, mETE, and gETE. In terms of the response to therapy, patients with gETE had higher rates of biochemical and/or structural incomplete responses within the first year of treatment (OR = 2.68 [95% CI 1.31-5.45], p = 0.007) and at the final follow-up evaluation (OR = 4.35 [95% CI 1.99-9.51], p < 0.001) compared with those with mETE. An analysis of the subgroups of microcarcinomas without lymph node metastases revealed no significant difference in DFS or the response to therapy between the low risk w/o ETE and mETE PTC groups. Conclusions: The results of this study suggest that both mETE and gETE are independent risk factors for the risk of recurrence in PTC. Although gETE has a more pronounced impact on the recurrence risk and is associated with a worse response to therapy, mETE may not be associated with a low risk of recurrence. This observation suggests that patients with PTC and mETE may, in part, have an intermediate risk of recurrence and need to be followed accordingly.

Prognostic value of tumor size and minimal extrathyroidal extension in papillary thyroid carcinoma

BACKGROUND

Tumour size and extrathyroidal extension (ETE) may impact papillary thyroid carcinoma (PTC) outcomes. We therefore examined the prognostic value of tumour size and ETE for predicting posttreatment recurrence in PTC patients.

METHODS

A total of 2,902 patients who underwent thyroidectomy for previously untreated T1-T3 PTC (7th edition American Joint Committee on Cancer) at our tertiary referral center were included. Univariate and multivariate Cox proportional hazard regression analyses were used to determine significant factors predictive of posttreatment recurrence-free survival (RFS).

RESULTS

In univariate analysis, tumour factors (including tumour size, multifocality, ETE, and lymphovascular invasion), nodal factors (including positive lymph node number, lymph node ratio, and extranodal extension), and MACIS (metastases, age, completeness of resection, invasion, and size) scores were significantly associated with RFS outcomes (P < 0.001). In multivariate analysis, tumour size >4 cm (P < 0.001) and multifocality (P = 0.038) were the independent factors of RFS. Nodal factors and MACIS scores were also independent factors of RFS.

CONCLUSION

Tumour size impacts RFS after thyroidectomy in T1-T3 PTC patients.

Recurrence following hemithyroidectomy in patients with low- and intermediate-risk papillary thyroid carcinoma

BACKGROUND

This study evaluated the incidence, patterns and risk factors for recurrence after hemithyroidectomy in patients with low- and intermediate-risk papillary thyroid carcinoma (PTC), and verified the predictive role of the risk staging systems in current use.

METHODS

The clinicopathological characteristics and risk categories were analysed according to recurrence in patients who underwent hemithyroidectomy for low- and intermediate-risk conventional PTC, and were followed up for at least 24 months. Five risk staging systems were used to stratify risk: the 2015 American Thyroid Association (ATA) system; Age, Metastases, Extent and Size (AMES) system; Metastases, Age, Complete resection, Invasion and Size (MACIS) system; Grade, Age, Metastases, Extent and Size (GAMES) system; and the eighth AJCC system.

RESULTS

The study included 561 patients; 93·9 per cent of the study population (527 of 561) had a papillary thyroid microcarcinoma 1 cm or smaller in size. At a mean follow-up of 83 months, 25 patients (4·5 per cent) had recurrence; among these patients, 23 (92%) presented with a remaining thyroid lobe. Multifocality was significantly associated with recurrence in univariable and multivariable analyses (adjusted hazard ratio 3·16, 95 per cent c.i. 1·25 to 7·98; P = 0·015). Disease-free survival (DFS) varied according to multifocality (P = 0·010). The five risk staging systems were not associated with recurrence, and their Harrell's C-index ranged from 0·500 to 0·531. DFS rates did not differ between the risk categories in each system.

CONCLUSION

Although the recurrence rate after hemithyroidectomy in patients with low- and intermediate-risk PTC was low, meticulous follow-up focusing on the remaining thyroid lobe is needed for early detection and timely management of recurrence. The risk scoring systems in current use have no predictive role in these patients.

Oncological impact of hypothyroidism and levothyroxine supplementation following hemithyroidectomy in patients with papillary thyroid carcinoma

BACKGROUND

We aimed to evaluate the oncological impact of hypothyroidism and levothyroxine (LT) supplementation after hemithyroidectomy in patients with papillary thyroid carcinoma (PTC).

METHODS

We retrospectively examined 401 patients who underwent hemithyroidectomy for classic PTC and who were postoperatively followed-up with ≥3 thyroid function measurements for ≥24 months.

RESULTS

During 77.4 months of follow-up, 268/401 patients (66.8%) developed hypothyroidism and 19/401 patients (4.7%) showed recurrence. Recurrence rates did not differ between the euthyroidism and hypothyroidism development groups. Recurrence rates were significantly lower in the LT group than in the no-LT group, although mean postoperative thyroid-stimulating hormone (TSH) levels were not different between the two groups. Univariate and multivariate analysis showed that tumors sized >1 cm and lack of LT supplementation were significantly associated with recurrence.

CONCLUSIONS

Postoperative hypothyroidism development was not a risk factor for PTC recurrence after hemithyroidectomy. Nevertheless, LT supplementation reduced recurrence risk without suppressing TSH.

Efficacy of hemithyroidectomy in papillary thyroid carcinoma with minimal extrathyroidal extension

PURPOSE

This study aimed to compare the oncologic outcomes of hemithyroidectomy with total thyroidectomy in clinically node-negative (cN0) papillary thyroid carcinoma (PTC) with minimal extrathyroidal extension (ETE).

METHODS

Among 1826 PTC patients who underwent thyroidectomy from Jan 2001 to Dec 2014, there were 255 with unilateral cN0 PTC with minimal ETE and of equal to or less than 2 cm in size; these 255 patients were included in this study. We excluded patients who had tumor size > 2 cm, bilateral tumors, clinically positive nodes, maximal or no ETE, gross invasion of sternothyroid muscle, recurrent cancers or distant metastases. Total thyroidectomy was performed in 173 of the 255 patients, and hemithyroidectomy in 82 of them. A propensity score-matched analysis was carried out to reduce selection bias, with the following covariates: sex, age, tumor size, multiplicity and central neck dissection.

RESULTS

In the baseline data of the 255 patients, female, age and tumor size were significantly higher in the total thyroidectomy group as was Stage III, whereas T and N classification did not differ in the two groups. Propensity score matching generated two matched groups of 66 patients each, in which the significant differences between the two groups seen in the baseline analysis disappeared. In the matched samples, recurrence rate (3.0% vs. 1.5%, p = 1.0) and recurrence-free survival curves did not differ between total thyroidectomy and hemithyroidectomy.

CONCLUSIONS

Hemithyroidectomy can be recommended for cN0 PTC 1 cm or less with minimal ETE. Also it can be considered for cN0 PTC 11-20 mm with minimal ETE.

RISK FACTORS FOR CENTRAL LYMPH NODE METASTASES IN PATIENTS WITH PAPILLARY THYROID MICROCARCINOMA

OBJECTIVES

Papillary thyroid carcinoma with a maximum tumor diameter no more than 10 mm is defined as papillary thyroid microcarcinoma (PTMC). The proportion of newly diagnosed PTMCs has increased significantly in recent years. Different guidelines have different comments about optimal management of PTMC, especially on prophylactic central lymph node (CLN) dissection. The aim of the present study was to analyze the risk factors for CLN metastases in patients with PTMC.

METHODS

A total of 4,389 patients underwent thyroid surgery at our center from January 2017 to March 2018, and 2,129 patients with PTMC were selected and assessed retrospectively. The relationship between CLN metastases and clinicopathologic features of PTMC were analyzed by both univariate and multivariate analyses.

RESULTS

Of the 2,129 patients with PTMC, CLN metastases were confirmed by pathology in 923 patients. Univariate and multivariate analyses found several independent factors associated with CLN metastases. They were male gender (odds ratio [OR], 1.694; 95% confidence interval [CI], 1.386 to 2.071; P<.001), younger age (<45 years) (OR, 2.687; 95% CI, 2.196 to 3.288; P<.001), larger tumor size (>5 mm) (OR, 2.168; 95% CI, 1.782 to 2.636; P<.001), positive CLN metastases via ultrasound (OR, 4.939; 95% CI, 3.534 to 6.902; P<.001), and multifocality (OR, 1.424; 95% CI, 1.176 to 1.724; P<.001).

CONCLUSION

CLN metastases are common in PTMC patients. Male gender, younger age (<45 years), larger tumor size (>5 mm), positive CLN metastases via ultrasound, and multifocality are independent risk factors for CLN metastases. Our data should be considered in the decision-making process related to performing CLN dissection.

ABBREVIATIONS

CLN = central lymph node; PTC = papillary thyroid carcinoma; PTMC = papillary thyroid microcarcinoma.

Ultrasonographic features associated with false-negative and false-positive results of extrathyroidal extensions in papillary thyroid microcarcinoma

PURPOSE

To assess the ultrasonographic features affect accuracy of extrathyroid extension (ETE) evaluation on preoperative ultrasonography (US) in papillary thyroid microcarcinoma (PTMC).

METHODS

Of the total patients who underwent thyroid surgery, 516 patients with a tumor measuring less than 1 cm on preoperative US were enrolled in this study. One blinded head and neck radiologist reviewed the preoperative US images to evaluate the US features of PTMC, and the pathologic reports were reviewed. The diagnostic accuracy rates, including sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy, were calculated, and the factors associated with false-negative and false-positive results for ETE were analyzed.

RESULTS

The sensitivity, specificity, PPV, NPV, and accuracy for predicting ETE according to sonographic criteria were 32.8%, 87.5%, 51.0%, 76.6%, and 71.7%, respectively. Non-adjacent to the trachea and unilateral lesion on US were significant factors associated with false-negative results.

CONCLUSION

Size, shape, and location of PTMC on US are important factors that affect the US results in ETE evaluation.

Small papillary thyroid carcinoma with minimal extrathyroidal extension should be managed as ATA low-risk tumor

PURPOSE

According to American Thyroid Association (ATA) guideline, papillary thyroid cancer (PTC) with minimal extrathyroidal extension (mETE) is classified at "intermediate risk" of persistent/recurrent disease. However, the impact of mETE per se on patients' outcome is not fully understood. The aim of our study was to evaluate the prognostic significance of mETE in patients with PTC not submitted to therapeutic or prophylactic lymph node dissection, according to tumor size and other prognostic factors.

PATIENTS AND METHODS

We retrospectively evaluated a total of 514 PTC patients: 127 (24.7%) had mETE (pT3Nx) and 387 (75.3%) had negative margins (pT1-2Nx). At a median follow-up of 9.1 years, patients were divided in two groups: patients with "good outcome" (no evidence of disease) and patients with "poor outcome" (persistent structural disease or recurrent disease or tumor-related death).

RESULTS

The rate of patients with "poor outcome" was significantly higher in patients with mETE compared with patients with negative margins (11.8 versus 5.1%; OR 2.4576, 95% CI 1.2178-4.9594, p = 0.01). However, mETE was significantly associated with poor outcome only in patients with tumors larger than 1.5 cm.

CONCLUSIONS

mETE is an unfavorable prognostic factor in tumors larger than 1.5 cm, suggesting that, in the absence of other unfavorable characteristics, smaller tumors with mETE should be classified and managed as "low risk" tumors.

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.

Prognostic indicators for papillary thyroid carcinoma

Differentiated thyroid cancer (DTC) includes more than 90% of all thyroid carcinoma and its incidence is growing, mainly due to an increase in the incidence of papillary thyroid cancer (PTC) for the widespread use of neck ultrasonography. Areas covered: Several prognostic factors should be considered during the management of PTC in order to provide the most effective treatment. The most important prognostic factors in PTC include personal and pathological features such as patient's age, gender, hystotype, tumor size, extrathyroidal extension, lymph node involvement, presence of local or distant metastases and molecular analyses. We performed a search in the PubMed database for studies published in English since 1960 using the terms: 'thyroid cancer', 'prognostic factors', 'age', 'gender', 'hystotype', 'tumor size', 'extrathyroidal extension', 'lymph node', 'metastases' and 'molecular analyses'. Expert commentary: Prognostic factors can guide clinicians during the treatment and follow-up of DTC patients, but it is now evident that the risk of recurrence or death must be evaluated periodically, on the basis of individual risk, according to the response to initial therapy or the subsequent therapy required during follow-up.

Reappraisal of the indication for radioiodine thyroid ablation in differentiated thyroid cancer patients

Radioactive iodine therapy is administered to patients with differentiated thyroid cancer (DTC) for eradication of thyroid remnant after total thyroidectomy or, in patients with metastatic disease, for curative or palliative treatment. In past years, thyroid remnant ablation was indicated in almost every patient with a diagnosis of DTC. Nowadays, careful revision of patients' outcome has introduced the concept of risk-based selection of patients candidate to thyroid remnant ablation. The present review aims to underline the indications for thyroid remnant ablation and to address methodologies to be employed.

Feasibility Study of Ultrasonographic Criteria for Microscopic and Macroscopic Extra-Thyroidal Extension Based on Thyroid Capsular Continuity and Tumor Contour in Patients with Papillary Thyroid Carcinomas

Our purpose was to evaluate the feasibility of using ultrasonographic criteria of thyroid capsular continuity and tumor contour to differentiate macroscopic extra-thyroidal extension (ETE) from microscopic ETE, as well as non-ETE from ETE. On ultrasonography, we evaluated thyroid capsular continuity (C0 = continuous, C1 = discontinuous, C2 = invisible), and thyroid tumor contour (P0 = in normal parenchyma, P1 = abutting, P2 = bulging), which were grouped into type 1-9 classifications. Either C1-2 or P1-2 was more prevalent in ETE than non-ETE. C1 and P2 tended to be associated with macroscopic ETE, whereas C0 and P1 were significantly associated with microscopic ETE. Types 6, 8 and 9 were more likely to have ETE than non-ETE; type 6 (C1 P2) and type 9 (C2 P2) were significantly associated with macroscopic ETE, whereas type 8 (C2 P1) was associated more with microscopic ETE. Macroscopic and microscopic ETE, as well as non-ETE and ETE, can be differentiated using these pre-operative ultrasonographic criteria.

Risk prediction and clinical model building for lymph node metastasis in papillary thyroid microcarcinoma

The surgical management of papillary thyroid microcarcinoma (PTMC), especially regarding the necessity of central/lateral lymph node dissection, remains controversial. This study investigated the clinicopathologic factors predictive of lymph node metastasis (LNM) in patients diagnosed with PTMC. Multivariate logistic regression analysis was used for PTMC patients identified from the Surveillance, Epidemiology, and End Results database who were treated by surgery between 2002 and 2012, to determine the association of clinicopathologic factors with LNM. According to the results, a total of 31,017 patients met the inclusion criteria of the study. Final histology confirmed 2,135 (6.9%) cases of N1a disease and 1,684 cases (5.4%) of N1b disease. Our multivariate logistic regression analysis identified variables associated with both central LNM and lateral lymph node metastasis (LLNM), including a younger age (<45 years), male sex, non-Hispanic white and other race, classical papillary histology, larger tumor size, multifocality, and extrathyroidal extension; distant metastasis was also significantly associated with LLNM. The significant predictors identified from multivariable logistic regression were integrated into a statistical model that showed that extrathyroidal extension had maximum weight in the predictive role for LNM. LLNM was validated to be a significant risk factor for cancer-specific death in Cox regression analyses, whereas central LNM failed to predict a worse cancer-specific survival according to our data. Therefore, we suggested that central lymph node dissection could be performed in certain patients with risk factors. Given the prevalence of LLNM in PTMC, a thorough inspection of the lateral compartment is recommended in PTMC patients with risk factors for precise staging; from the viewpoint of a radical treatment for tumors, prophylactic lateral lymph node dissection that aims to remove the occult lateral lymph nodes may be an option for PTMC with risk factors. Multicenter studies with long-term follow-up are recommended to better understand the risk factors and surgical management for cervical nodes in PTMC.

Overexpression of long non-coding RNA NR_036575.1 contributes to the proliferation and migration of papillary thyroid cancer

Current evidence suggests that the human genome produces a large number of non-coding RNAs, including microRNAs and long non-coding RNAs (lncRNAs). Generally, lncRNAs are defined as RNA transcripts longer than 200 nucleotides that are not transcribed into proteins. In recent years, lncRNAs have been reported to play oncogenic roles in tumourigenesis. However, minimal research has been performed on the expression and clinicopathological significance of lncRNAs in papillary thyroid cancer (PTC). In the present study, we investigated not only the expression and clinicopathological significance of a novel lncRNA, NR_036575.1, in PTC tissues and adjacent non-cancerous tissues but also its potential function in TPC1 cells. The expression levels of the lncRNA NR_036575.1 in 83 pairs of PTC tissues and adjacent non-cancerous tissues were detected via quantitative real-time polymerase chain reaction. The relationships between the expression levels and clinicopathological characteristics of the lncRNA NR_036575.1 were analysed. In addition, we established two receiver operating characteristic (ROC) curves to assess the diagnostic value of NR_036575.1 expression. Cell Counting Kit-8 and transwell assays were used to assess cell proliferation and migration, respectively. The expression levels of the lncRNA NR_036575.1 were significantly higher in PTC tissues than in adjacent non-cancerous tissues. High NR_036575.1 expression was associated with extrathyroidal extension (ETE) (P = 0.011) and tumour size (P = 0.006). The ROC curves indicated that NR_036575.1 could potentially serve as a biomarker for identifying PTC and related, non-cancerous diseases (sensitivity, 80.7 %; specificity, 88 %), as well as for differentiating between PTC with or without ETE (sensitivity, 57.8 %; specificity, 86.7 %). NR_036575.1 knock-down significantly inhibited the proliferation and migration of TPC1 cells. Our findings are the first to describe lncRNA NR_036575.1 overexpression in PTC. NR_036575.1 expression was associated with both ETE and tumour size. In addition, NR_036575.1 modulation could regulate TPC1 cell proliferation and migration. The results of our study suggest that NR_036575.1 could be applied as a potential biomarker and a novel therapeutic target for PTC patients.

Clinical and Pathologic Predictors of Lymph Node Metastasis and Recurrence in Papillary Thyroid Microcarcinoma

BACKGROUND

The treatment for patients with papillary thyroid microcarcinoma (PTMC) is controversial because PTMC is often found incidentally and its prognosis is very good. Lymph node metastasis (LNM) is one of the main predictors of recurrence and survival. This retrospective study aimed to identify clinical and pathologic factors that increase the risk of metastasis or recurrence, in order to isolate clinically unfavorable PTMCs to help guide therapy.

METHODS

Clinical and pathologic data were collected from 273 patients diagnosed with PTMC at The University of Chicago Medical Center between 2000 and 2011. Data points included age, sex, race/ethnicity, tumor size, multifocality, thyroiditis, extrathyroidal extension (ETE), surgical margins, preoperative clinical suspicion of cancer, central/lateral lymph nodes removed and lymph nodes with metastatic carcinoma, treatment, local recurrence, distant recurrence, and survival.

RESULTS

Multivariate logistic regression showed that age <45 years (odds ratio [OR] = 3.565 [confidence interval (CI) 1.137-11.177]), multifocality (OR = 3.556 [CI 1.066-11.855]), and ETE (OR = 4.622 [CI = 1.068-20.011]) significantly increased the risk of central LNM (CLNM). However, sex, size of tumor, thyroiditis, positive margins, and clinical suspicion were not correlated with an increased risk for CLNM. Multivariate logistic regression showed that only ETE (OR = 16.066 [CI 1.850-139.488]) significantly increased the risk of lateral LNM. In the cohort of 202 patients with follow-up data, only six recurred. Median time to recurrence was approximately 12 months (range 3.5-120 months), and median follow-up was 42 months. No patient had distant metastasis, and no patients died.

CONCLUSIONS

PTMC is an indolent disease, but does pose a risk for LNM and local recurrence. More aggressive treatment or more frequent follow-up could be considered for patients with unfavorable features (age <45 years, multifocality, ETE), especially in the setting of involved lymph nodes at the time of surgical resection, as these patients may be at an increased risk for recurrence.

Preliminary study of optical coherence tomography imaging to identify microscopic extrathyroidal extension in patients with papillary thyroid carcinoma

BACKGROUND AND OBJECTIVES

We evaluated the feasibility of using optical coherence tomography (OCT), to identify microscopic extrathyroidal extension (mETE) in ex vivo thyroidectomy specimens of patients who underwent thyroidectomy for the treatment of papillary thyroid carcinoma (PTC).

METHODS

A total of 170 ex vivo OCT images of the tumor, were acquired just after completion of thyroidectomy in 17 patients. The OCT images of each patient were separately evaluated by two blinded investigators, and the outcomes were compared with the histopathology reports.

RESULTS

The sensitivity and specificity of mETE identification from the OCT images were 81.4% and 86.0%, respectively, for the first investigator, and 82.9% and 87.0%, respectively, for the second investigator. Substantial agreement between the investigators was verified by Cohen's κ (Cohen's κ = 0.772).

CONCLUSION

In this preliminary study of a limited series of ex vivo thyroidectomy specimens, we verified the feasibility of OCT as a method of identifying mETE in patients with PTC.

Patients with Papillary Thyroid Carcinoma at Intermediate Risk of Recurrence According to American Thyroid Association Criteria Can Be Reclassified as Low Risk When the Postoperative Thyroglobulin Is Low

BACKGROUND

According to American Thyroid Association (ATA), all patients with papillary thyroid carcinoma (PTC) should initially be classified regarding the risk of tumor recurrence. If a very high postoperative thyroglobulin (Tg) classifies patients as high risk of recurrence, it is reasonable to hypothesize that, at the other extreme, a low Tg may reclassify patients from intermediate to low risk. The objective of this study was to evaluate the rate of persistent/recurrent disease in intermediate-risk patients with low postoperative (before 131I) Tg, thereby evaluating whether these patients can be reclassified as low risk based on this finding already at the time of initial therapy rather than one to two years after radioiodine therapy.

METHODS

A total of 181 patients with the following characteristics were evaluated: (i) diagnosis of PTC; (ii) submitted to total thyroidectomy with lymph node dissection in the case of a suspicion of metastases based on preoperative ultrasonography (US) or perioperative evaluation (cN1); (iii) apparently without persistent tumor after surgery; (iv) a postoperative stimulated Tg (sTg) ≤2 ng/mL and negative anti-Tg antibodies (TgAb); and (v) considered to be at intermediate risk by ATA criteria.

RESULTS

When evaluated 9-12 months after radioiodine therapy, 170 patients (94%) had a sTg <1 ng/mL and negative TgAb and a negative neck US (excellent response). Ten patients (5.5%) had a sTg >1 ng/mL (≤2 ng/mL) in the absence of apparent disease detected by imaging methods (indeterminate response). US detected cervical lymph node metastases (not detected at the time of 131I therapy) in one patient (incomplete structural response). During follow-up, recurrence was observed in 5/180 (2.7%) patients without apparent disease in the initial assessment. Thus, persistent or recurrent disease occurred in only 3.3% of cases. The 175 patients without tumor persistence/recurrence were not submitted to any additional therapy, and all had a Tg/thryoxine <1 ng/mL in the last assessment. There was no case of death related to the disease.

CONCLUSIONS

This study suggests that intermediate-risk patients (according to ATA criteria) with a postoperative sTg ≤2 ng/mL can be reclassified as low risk already at the time of initial therapy.

Intraoperative frozen section for the evaluation of extrathyroidal extension in papillary thyroid cancer

BACKGROUND

We investigated extrathyroidal extension (ETE) through frozen biopsy for intraoperative decision making in patients with papillary thyroid cancer (PTC).

METHODS

During the period of the study an operation was performed in 268 patients with PTC and ETE was evaluated using intraoperative frozen biopsies of thyroid tissue.

RESULTS

Extrathyroidal extension was confirmed in 54 patients (20 %) on frozen biopsy. Fifty-three patients among 54 patients showing ETE on frozen biopsy were confirmed on permanent pathologic analysis. Accordingly, frozen biopsy had a sensitivity of 66 %, a specificity of 99 %, a positive predictive value of 98 %, and a negative predictive value of 87 %. Tumor size (OR 4.373; CI 2.257-8.475, p = <0.001) was an independent factor for predicting ETE on frozen biopsy.

CONCLUSIONS

Intraoperative frozen biopsy can be an useful tool in identifying the presence of ETE. It can also help the operator decide the extent of surgery and central neck dissection in patients with PTC.

Intrathyroidal tumors presenting with extranodal extension: what are we missing?

Extranodal extension (ENE) is an indicator of poor prognosis in well-differentiated thyroid cancer (WDTC). We have demonstrated that extrathyroidal extension (ETE) predicts ENE in patients with positive lymph nodes, indicating concordance between primary tumor and lymph node biology. In an effort to determine if there were other histologic features of the primary tumors that indicated an aggressive biology, we examined a subset of patients with intrathyroidal (T1/T2) disease whose lymph nodes had ENE. A review was conducted from January 2004 to March 2013. The histologic features of ETE-negative/ENE-positive tumors (group A, 12 cases) were compared with a random sample of ETE-negative/ENE-negative node-positive patients (group B, 27 cases). Cases were reviewed for size, capsule presence, infiltration, sclerosis, lymphocytic thyroiditis (LT), psammoma bodies, lymphovascular invasion (LVI), perineural invasion (PNI), architecture/cytomorphology, and focality. Size was compared using the Mann-Whitney test, while the remaining features were compared using a Fischer exact test. The breakdown of pathologic features of groups A/B were as follows: 2.28 cm/1.46 cm mean tumor size, 90 %/67 % unencapsulated, 100 %/89 % infiltrative, 100 %/89 % sclerotic, 60 %/52 % LT, 30 %/59 % positive psammoma bodies, 0 %/11 % LVI, 0 %/4 % PNI, 90 %/96 % classic architecture, 50 %/44 % multifocal. Neither size (p = 0.072) nor the other nine histologic features examined reached statistical significance. None of the histologic features appeared to significantly predict ENE. Further examination of intrathyroidal tumors at a molecular level is necessary to determine if there are any identifiable features of intrathyroidal tumors that predict ENE and thus a more aggressive phenotype.