Clinical implications of microscopic extrathyroidal extension in patients with papillary thyroid carcinoma

Patterns of cervical lymph node involvement in mono-focal papillary thyroid carcinoma patients with different capsular status: A multi-center analysis

OBJECTIVE

The characteristics of cervical lymph node involvement in papillary thyroid carcinoma (PTC) patients with different degree of capsular invasion remains unclear, especially for those with mono-focal lesion who have traditionally been considered as low neck metastasis risk subgroup.

STUDY DESIGN

Retrospective cohort study.

SETTING

Three academic teaching hospital.

METHODS

A total of 1276 mono-focal PTC patients were retrospectively analyzed.

RESULTS

Mono-focal PTC patients with extrathyroidal extension (ETE) showed significantly higher central lymph node metastasis (CLNM) rate than those without. For patients with no gross ETE (gETE), those with minimal ETE (mETE) also showed more commonly CLNM than those with encapsulated lesions. However, the lateral lymph node metastasis (LLNM) rates of patients with mETE and encapsulated tumors were comparable, both lower than that of patients with gETE. Age ≥40, male, and MTD ≥0.5 cm were identified as independent risk factors of CLNM for those with encapsulated tumors and were enrolled for creating a prediction model. In terms of LLNM, only MTD ≥1.0 cm was confirmed as independent risk factors of LLNM for patients with positive gETE.

CONCLUSIONS

The presence and degree of ETE may have different effects on the risk of central and lateral lymph node metastasis. gETE demonstrates a strong correlation with both CLNM and LLNM while mETE is only associated with CLNM in mono-focal PTC patients. A comprehensive model is established in the aim of predicting neck involvement according to the capsular status and the corresponding stratified risk factors, which may aid clinical decision-making for the management of neck regions.

Machine learning algorithms for identifying contralateral central lymph node metastasis in unilateral cN0 papillary thyroid cancer

Purpose

The incidence of thyroid cancer is growing fast and surgery is the most significant treatment of it. For patients with unilateral cN0 papillary thyroid cancer whether to dissect contralateral central lymph node is still under debating. Here, we aim to provide a machine learning based prediction model of contralateral central lymph node metastasis using demographic and clinical data.

Methods

2225 patients with unilateral cN0 papillary thyroid cancer from Wuhan Union Hospital were retrospectively studied. Clinical and pathological features were compared between patients with contralateral central lymph node metastasis and without. Six machine learning models were constructed based on these patients and compared using accuracy, sensitivity, specificity, area under the receiver operating characteristic and decision curve analysis. The selected models were then verified using data from Differentiated Thyroid Cancer in China study. All statistical analysis and model construction were performed by R software.

Results

Male, maximum diameter larger than 1cm, multifocality, ipsilateral central lymph node metastasis and younger than 50 years were independent risk factors of contralateral central lymph node metastasis. Random forest model performed better than others, and were verified in external validation cohort. A web calculator was constructed.

Conclusions

Gender, maximum diameter, multifocality, ipsilateral central lymph node metastasis and age should be considered for contralateral central lymph node dissection. The web calculator based on random forest model may be helpful in clinical decision.

The impact of microscopic extrathyroidal extension on the clinical outcome of classic subtype papillary thyroid microcarcinoma: a multicenter study

OBJECTIVES

Despite the presumed overdiagnosis of papillary thyroid microcarcinoma (PTMC) which has resulted in a new trend toward less-extensive surgery and a preference for active surveillance, the impact of microscopic extrathyroidal extension (mETE) on the clinical outcomes of PTMC is still controversial. This study assessed the impact of mETE on the clinical outcomes of patients with classic subtype PTMC.

METHODS

The data of consecutive patients who underwent thyroidectomy and were histopathologically diagnosed as classic subtype PTMC were analyzed. Cox's proportional hazards model was used to assess the impact of contributing variables on persistent/recurrent disease. Disease-free survival was estimated using the Kaplan-Meier method.

RESULTS

This study included 1013 patients (84% females), with a mean follow-up period of 62.5 ± 35.3 months. Patients with mETE had a significantly higher rate of locoregional persistent/recurrent disease than patients without mETE (9.8% vs 2.1%, p < 0.001). The disease-free survival rate was significantly lower in patients with mETE than in those without (90.2% vs 97%, Log-Rank p < 0.001). Furthermore, mETE and neck lymph node involvement were independent predictors of persistent/recurrent disease in multivariate analysis (HR: 2.43, 95% CI:1.02-5.81, p = 0.043; HR: 4.38, 95% CI: 1.7-11.2, p = 0.002, respectively).

CONCLUSIONS

In patients with the classic subtype of PTMC, mETE is an independent predictor of persistent/recurrent disease and is associated with a lower DFS rate. However, neck lymph node involvement is the strongest predictor of persistent/recurrent disease. Therefore, PTMCs with mETE and neck lymph node involvement are at a higher risk of persistent/recurrent disease than individuals lacking both characteristics.

Analysis of preoperative computed tomography radiomics and clinical factors for predicting postsurgical recurrence of papillary thyroid carcinoma

BACKGROUND

Postsurgical recurrence is of great concern for papillary thyroid carcinoma (PTC). We aim to investigate the value of computed tomography (CT)-based radiomics features and conventional clinical factors in predicting the recurrence of PTC.

METHODS

Two-hundred and eighty patients with PTC were retrospectively enrolled and divided into training and validation cohorts at a 6:4 ratio. Recurrence was defined as cytology/pathology-proven disease or morphological evidence of lesions on imaging examinations within 5 years after surgery. Radiomics features were extracted from manually segmented tumor on CT images and were then selected using four different feature selection methods sequentially. Multivariate logistic regression analysis was conducted to identify clinical features associated with recurrence. Radiomics, clinical, and combined models were constructed separately using logistic regression (LR), support vector machine (SVM), k-nearest neighbor (KNN), and neural network (NN), respectively. Receiver operating characteristic analysis was performed to evaluate the model performance in predicting recurrence. A nomogram was established based on all relevant features, with its reliability and reproducibility verified using calibration curves and decision curve analysis (DCA).

RESULTS

Eighty-nine patients with PTC experienced recurrence. A total of 1218 radiomics features were extracted from each segmentation. Five radiomics and six clinical features were related to recurrence. Among the 4 radiomics models, the LR-based and SVM-based radiomics models outperformed the NN-based radiomics model (P = 0.032 and 0.026, respectively). Among the 4 clinical models, only the difference between the area under the curve (AUC) of the LR-based and NN-based clinical model was statistically significant (P = 0.035). The combined models had higher AUCs than the corresponding radiomics and clinical models based on the same classifier, although most differences were not statistically significant. In the validation cohort, the combined models based on the LR, SVM, KNN, and NN classifiers had AUCs of 0.746, 0.754, 0.669, and 0.711, respectively. However, the AUCs of these combined models had no significant differences (all P > 0.05). Calibration curves and DCA indicated that the nomogram have potential clinical utility.

CONCLUSIONS

The combined model may have potential for better prediction of PTC recurrence than radiomics and clinical models alone. Further testing with larger cohort may help reach statistical significance.

Factors influencing extrathyroidal extension of papillary thyroid cancer and evaluation of ultrasonography for its diagnosis: a retrospective analysis

Pathologists usually explore extrathyroidal extensions (ETEs) in thyroid cancer; however, sonographers are often not concerned with ETEs. We investigated factors influencing ETEs and the efficacy of ultrasound evaluation of thyroid capsule invasion. We retrospectively analysed 1933 papillary thyroid carcinoma patients who underwent thyroidectomy during 2018-2021. Patients were divided into three groups: no ETE, minor ETE (mETE), and gross ETE. Clinical characteristic differences were assessed using binary logistic regression analysis to identify ETE predictors, and the kappa test was performed to analyse consistency between ultrasonographic and pathological diagnoses of ETE. The mETE group was more likely to have larger tumour diameters and more extensive lymph node metastasis (LNM) than the no ETE group and more likely to be diagnosed in the isthmus. In the multivariate logistic regression analysis, longest tumour diameter, lesion site, LNM extent, and thyroglobulin concentration were significant mETE predictors. Minimal consistency existed between pathological and ultrasonographic examinations for neighbouring tissue invasion. Many clinical differences were observed between the no ETE and mETE groups, suggesting the importance of considering mETE. Therefore, sonographers should pay more attention to relationships between nodules and capsule and indicate these on ultrasound reports to provide more accurate preoperative ETE information for surgeons.

Optimal Cutoff Values of the Contact Angle of Tumor on Sonography System for Predicting Extrathyroidal Extension of Papillary Thyroid Carcinoma by Tumor Location

Background

Extrathyroidal extension (ETE) significantly affects the treatment strategy for thyroid cancer. We present a new method to predict ETE of papillary thyroid carcinoma (PTC).

methods

We enrolled 1 481 patients with PTCs. The ETE was classified into minimal and gross ETE. Using the novel "contact angle of the tumor on sonography" (CATS) system, we calculated optimal cutoffs for predicting ETE according to tumor location and compared the diagnostic performance to that of previous methods.

Results

The optimal cutoff angles for predicting anterior minimal and gross ETE were 41.5° and 49.4°, respectively, while those for posterior ETE were 39.8° and 54.6°, respectively. The optimal cutoff angle predicting tracheal ETE was 88.0°. The diagnostic performance was comparable to that of previous methods.

Conclusion

The CATS method for predicting ETE is a valuable alternative.

Impact of microscopic extrathyroidal extension on differentiated thyroid cancer post-surgical risk of recurrence: a retrospective analysis

PURPOSE

In the last edition of the American Joint Committee on Cancer (AJCC) staging system, differentiated thyroid cancers (DTC) showing microscopic extrathyroidal extension (mETE) are considered comparable to intrathyroidal cancers for their clinical behavior and prognosis. The aim of the study is to evaluate the impact of this updated assessment of T, when applied to the postoperative recurrence risk stratification, according to the American Thyroid Association Guidelines (ATA-RR).

METHODS

One-hundred DTC patients who underwent total thyroidectomy were retrospectively evaluated. The downstaging of mETE was introduced in the definition of T, and the updated classification defined as modified ATA-RR (ATAm-RR). For each patient, post-surgical basal and stimulated thyroglobulin (Tg) levels, neck ultrasound (US) and post-ablative 131-I whole body scan (WBS) reports were considered. The predictive performance (PP) of disease recurrence was calculated both for each single parameter, as well as for all of them.

RESULTS

According to ATAm-RR classification, 19/100 patients (19%) were downstaged. ATA-RR proved a significant PP for disease recurrence (DR) (sensitivity 75.0%, specificity 63.0%, p = 0.023). However, ATAm-RR performed slightly better due to an increased specificity (sensitivity 75.0%, specificity 83.7%, p < 0.001). For both classifications, the PP was optimal when all the above-mentioned predictive parameters were considered.

CONCLUSION

Our results suggest that the new assessment of T considering mETE resulted in a downgrading of ATA-RR class in a significant number of patients. This provides a better PP for disease recurrence, and the best PP was obtained when considering the whole predictive variables together.

Extrathyroidal extension or tumor size of primary lesion influences thyroid cancer outcomes

AIMS

Extrathyroidal extension (ETE) is a determined factor of T3 and T4 stage of differentiated thyroid cancer (DTC) in American Joint Committee on Cancer. We aimed to compare clinical outcomes between different extent of ETE according to tumor size.

METHODS

Patients diagnosed with DTC were collected from the Surveillance, Epidemiology, and End Results database from 2004 to 2015. They were categorized into two groups by presence of lymph node metastases (LNM) or distant metastases (DM): group A: no presence of LNM and DM, and group B: presence of LNM or DM. Each group was further divided into four groups according to tumor size: <1 cm, 1-2 cm, 2-4 cm, >4 cm. ETE was divided into three groups by the extent: no ETE, microscopic ETE, and macroscopic ETE. Kaplan-Meier method and log-rank test were used to analyze cancer-specific survival (CSS).

RESULTS

91,975 patients were included. In groups A and B, for tumor size 1 cm, there was no significant difference in CSS between no ETE and microscopic ETE, while a significant difference was observed between no ETE and macroscopic ETE. For tumor size >1 cm, there were significant differences in CSS (both no ETE vs. micro ETE and no ETE vs. macro ETE).

CONCLUSION

We suggests that when tumor size is more than 1 cm, micro ETE is significantly associated with poorer outcome. T3 and T4 stages may take account into tumor size rather than merely based on the presence and extent of ETE. It may be prudent to revisit the omission of micro ETE in TNM staging.

Cervical exenteration and its variants for locally advanced thyroid cancer: when, why, and how?

PURPOSE OF REVIEW

To describe the modern surgical approach for management of advanced thyroid cancers infiltrating the cervicovisceral axis with special attention to well differentiated tumors not amenable to organ-sparing techniques. In particular, cervical exenteration, herein defined as the sum of total thyroidectomy, central compartment and lateral neck dissections, variously associated with total laryngectomy and possible partial or total pharyngoesophagectomy, represents an extreme surgical procedure that, in properly selected cases, allows for reasonable palliation of central compartment life-threatening signs/symptoms if not cure for an advanced oncologic condition.

RECENT FINDINGS

Cervical exenteration is not contraindicated by the presence of limited distant metastases at presentation. Even though it requires that the patient is in general good health as it can be associated with a number of complications and long in-hospital stay, when appropriately planned and performed according to the most recent reconstructive nuances, it allows good oncologic outcomes that are not inferior to those described for similarly advanced primaries of the upper aerodigestive tract. In addition, quality of life and functional results are not significantly different from those described after total laryngectomy for primary laryngeal squamous cell carcinomas.

SUMMARY

Cervical exenteration requires a tertiary, expert, multidisciplinary effort in terms of diagnosis, surgical performance, and postoperative care. A patient-centered decision process is strongly warranted taking into consideration alternative therapeutic and symptom-based palliative strategies.

Central and lateral neck involvement in papillary thyroid carcinoma patients with or without thyroid capsular invasion: A multi-center analysis

PURPOSES

To quantitatively predict the probability of cervical lymph node metastasis for papillary thyroid carcinomas (PTC) patients with or without thyroid capsular invasion (TCI), to guide the decision-making of management strategies for neck regions.

METHODS

A total of 998 PTC patients from three medical centers were retrospectively analyzed.

RESULTS

Patients with positive TCI (TCI group) exhibited higher risks for both CLNM and LLNM than those with negative TCI (no-TCI group). Patients receiving lateral lymph node dissection showed significantly higher incidence of relatively severe postoperative complications. For no-TCI group, factors including age less than 55 years old, male, the presence of bilateral disease and multifocality, and maximum tumor diameter (MTD)>=0.5cm were confirmed to be independent risk factors for CLNM, while the presence of bilateral disease and ipsilateral nodular goiter (iNG), and maximum positive CLN diameter (MCLND)>1.0cm independent factors for LLNM. Independent risk factors of LLNM for patients within the TCI group included MCLND>1.0cm, positive CLN number>=3, and the presence of iNG. Predictive models of CLNM and LLNM were established based on the aforementioned risk factors for patients within no-TCI and TCI groups. A meticulous and comprehensive risk stratification flow chart was established for a more accurate evaluation of central neck involvement including both CLNM and LLNM risk in PTC patients.

CONCLUSIONS

A meticulous and comprehensive stratification flow chart for PTC patients for quantitatively evaluating both CLNM and LLNM was constructed.

The clinical impact of extrathyroidal extensions on prognoses in pediatric differentiated thyroid cancers

BACKGROUND

The prognostic impact of extrathyroidal extensions (ETE) on clinical outcomes has not been well studied in pediatric thyroid cancers. The aim of this study was to analyze the clinicopathological characteristics and clinical outcomes according to the extent of ETE in pediatric and adolescent thyroid cancers.

METHODS

This study retrospectively reviewed 89 papillary thyroid carcinoma (PTC) patients less than 19 years of age who underwent total thyroidectomy with central neck dissections (CND) between 1997 and 2018. We compared the clinicopathological features among three groups: no ETE, microscopic ETE, and gross ETE.

RESULTS

The median follow-up time was 111 months. The mean age was 15.3 years and the mean tumor size was 2.4 cm. Tumor sizes larger than 2 cm (OR = 9.2, p = 0.001), exhibited bilaterality (OR = 4.3, p = 0.006), were an aggressive variant (OR = 5.8, p = 0.006), and exhibited central lymph node metastasis (OR = 1.3, p = 0.018), lateral lymph node metastasis (OR = 9.2, p = 0.001), recurrence (OR = 3.9, p = 0.038), and distant metastasis (OR = 4.4, p = 0.016) were associated with gross ETE. There was no remarkable difference in clinicopathological characteristics between the no ETE group and microscopic ETE group, except for aggressive variants (OR = 5.5, p = 0.008). There was a significant difference in recurrence-free survival (RFS) rates according to the extent of ETE (p = 0.025). Furthermore, the distant metastasis-free survival curve presented a significant difference among the three groups (p = 0.018). Both microscopic ETE and gross ETE were significantly associated with worse prognoses in pediatric thyroid cancers.

CONCLUSIONS

We recommend that microscopic ETE should be included in the intermediate risk category and that gross ETE should be stratified in the high risk group in future revisions of ATA pediatric guidelines.

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.

Prognostic Impact of Microscopic Extra-Thyroidal Extension (mETE) on Disease Free Survival in Patients with Papillary Thyroid Carcinoma (PTC)

Background: This study assessed the risk of reduced disease-free survival (DFS) and poor clinical outcome in patients with papillary thyroid carcinomas (PTC) with microscopic extra-thyroidal extension (mETE), as compared to PTC patients without mETE. Methods: Retrospective analysis of a prospective database of patients treated by total thyroidectomy and radioactive iodine (RAI) with a five-year follow-up and tumors < 40 mm. In total, 303 patients were analyzed: 30.7% presented tumors with mETE, and 69.3% without. mETE was defined as extra-thyroidal invasion without skeletal muscle involvement. The primary outcome, DFS, was defined as the interval between initial treatment and any subsequent PTC-related treatment. The second outcome was the clinical status at five years. Results: In univariate analyses, the five-year DFS was significantly lower for tumors with mETE (62.4% versus 88.1%, p < 0.001). In multivariate analysis, mETE and massive lymph node involvement (LNI) were independent prognostic factors, associated respectively with a hazard ratio of 2.55 (95% CI 1.48−4.40) and 8.94 (95% CI 4.92−16.26). mETE was significantly associated with a pejorative clinical outcome at five years, i.e., biochemical/indeterminate response and structural persistence (Respectively OR 1.83 (95% CI 0.83; 4.06) and OR 4.92 (95% CI 1.87; 12.97)). Conclusion: Our results suggest that mETE is an independent poor prognosis factor of reduced DFS and predictive of poor clinical outcome.

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.

Utility and significance of clinical risk factor scoring model in predicting central compartment lymph node metastasis (CLNM) in patients with papillary thyroid cancer (PTC)

Objectives

To establish and discuss the significance of a clinical risk factor scoring model in predicting central compartment lymph node metastasis (CLNM) (level VI) in patients with papillary thyroid cancer (PTC).

Methods

A retrospective analysis was performed on 412 patients who underwent surgical treatment for PTC who were admitted to the Second Hospital of Hebei Medical University between July 2016 and May 2017, with the patients being divided into a CLNM group and a non-metastasis (NM) group. Risk factors such as sex, age, tumor diameter, capsular invasion, multifocality, and tumor location were recorded for scoring via maximum likelihood estimation (MLE)-based discriminant analysis. The scoring model was used for prospective analysis of CLNM in another 104 patients. Besides, the discriminant function that was developed using the risk factors based on the retrospective data derived from the 412 patients was evaluated by plugging the retrospective data in for specified variables, with a higher score indicating a greater risk of developing CLNM. Clinical diagnosis of CLNM was based on postoperative paraffin section pathology, which was adopted as the criterion to assess discriminative accuracy in the prospective and retrospective groups.

Results

The discriminative accuracy of the scoring model was 71.8% in the retrospective group and 72.2% in the prospective group.

Conclusions

The scoring model enables simplified, quantitative analysis of CLNM in PTC patients. The scoring model has clinical significance in that it provides a basis for the choice of operation, personalized postoperative treatment, and prognosis of PTC.

A critical analysis of the current TNM classification for differentiated thyroid carcinoma in young patients: Time for a change?

BACKGROUND

The current TNM classification that simply classifies differentiated thyroid carcinoma (DTC) patients younger than 55 years into stage I and stage II based on the presence or absence of distant metastases has been questioned. In this study, we reexamined the impact of T status and N status on prognosis and then developed a new prediction model to improve the predictability of cancer-specific survival (CSS) in young patients.

MATERIALS AND METHODS

Kaplan-Meier method was applied to calculate the CSS. Multivariable Cox proportional hazards models were used to assess the impact of T status and N status on CSS after adjustment for known covariates. The area under the receiver operating characteristic curve (AUC), C-index, Bayesian information criterion (BIC), and Akaike information criterion (AIC) were calculated to compare model performance.

RESULTS

A total of 9,242 DTC patients younger than 55 years were enrolled in the study. After adjusting for gender, age at diagnosis, race, pathology subtype, N stage, and M stage, T3 disease [hazard ratio (HR): 3.78, P = 0.006] and T4 disease (HR: 7.96, P < 0.001) remain independent predictors of CSS. Similarly, the 10-year CSS rate of N1b disease (HR: 3.78, P < 0.001) was significantly higher than that of N0 disease after adjustment. Moreover, Kaplan-Meier survival analysis showed that the 10-year CSS of stage II disease in younger patients with DTC showed a sharp decrease compared with that in older patients with DTC (74.47% vs. 98.43%, P < 0.001). Furthermore, a modified TNM staging system based on significantly prognostic T stage and N stage was established, which showed better performance than the current TNM staging system (P < 0.05). The new prediction model is also applicable to papillary thyroid carcinoma patients and follicular thyroid carcinoma patients.

CONCLUSIONS

This is the first study to question the rationality of the current TNM staging system for patients younger than 55 years and successfully develop a new prognostic model, which improves prognostic stratification and guides individualized management.

Does macroscopic extrathyroidal extension to the strap muscles alone affect survival in papillary thyroid carcinoma?

BACKGROUND

Macroscopic extrathyroidal extension to structures adjacent to the thyroid gland is one of the most important predictors of survival in papillary thyroid carcinoma. However, the prognostic significance of macroscopic extrathyroidal extension to strap muscles alone is unknown. The aim of this study is to determine the impact on survival in patients with macroscopic extrathyroidal extension to strap muscles alone compared to those with no macroscopic extrathyroidal extension and macroscopic extrathyroidal extension involving other adjacent structures.

METHODS

After institutional review board approval, adult papillary thyroid carcinoma patients were identified from an institutional database of 6,259 patients undergoing initial surgery for well-differentiated thyroid carcinoma from 1986 to 2015. Patients were classified as having no macroscopic extrathyroidal extension, macroscopic extrathyroidal extension to strap muscles alone, or macroscopic extrathyroidal extension to other adjacent structures. Disease-specific survival was calculated using the Kaplan-Meier method and groups were compared using the log-rank test. A P value < .05 was considered statistically significant and significant factors were used in a Cox proportional hazard model to predict disease-specific survival.

RESULTS

There were 5,880 patients included in the analysis; 5,485 patients (93.3%) in the no macroscopic extrathyroidal extension group, 179 (3.0%) in the macroscopic extrathyroidal extension to strap muscles alone group and 216 (3.7%) in the macroscopic extrathyroidal extension involving other adjacent structures group. With a median follow-up of 64 months, the estimated 10-year disease-specific survival for patients with no macroscopic extrathyroidal extension, macroscopic extrathyroidal extension to strap muscles alone, and macroscopic extrathyroidal extension involving other adjacent structures were 98.9%, 95.7%, and 83.7%, respectively (P < .0001). In the ≥55-year-old cohort, the estimated 10-year disease-specific survival for patients with no macroscopic extrathyroidal extension, macroscopic extrathyroidal extension to strap muscles alone, and macroscopic extrathyroidal extension involving other adjacent structures were 97.6%, 89.3%, and 68.1%, respectively (P <.0001). After controlling for pathological nodal stage and distant metastasis stage, extent of extrathyroidal extension remained an independent predictor of disease-specific survival; patients with macroscopic extrathyroidal extension to strap muscles alone had a 3.3-fold increased likelihood of a disease-specific death compared to no macroscopic extrathyroidal extension patients (hazard ratio 3.294; 95% confidence interval 1.076-10.086, P < .0368).

CONCLUSION

In our study, patients aged ≥55 years with papillary thyroid carcinoma and macroscopic extrathyroidal extension to strap muscles alone appear to have an increased likelihood of a disease-specific death compared to patients with no macroscopic extrathyroidal extension.

Development and validation of a nomogram based on stromal score to predict progression-free survival of patients with papillary thyroid carcinoma

Background

Growing evidence has proved that stromal cells, as the critical component of tumor microenvironment (TME), are closely associated with tumor's progression. However, the model based on stromal score to predict progression‐free survival (PFS) in papillary thyroid carcinoma (PTC) has not been developed. The study aimed at exploring the relation between stromal score and prognosis, then establishing a nomogram to predict PFS of patients with PTC.

Method

We obtained the stromal score and clinicopathological characteristics of PTC patients from The Cancer Genome Atlas (TCGA) database. Cox regression analysis assisted in selecting prognosis‐related factors. A stromal score‐based nomogram was built and verified in the training and validation cohorts, respectively. The calibration curve, concordance index (C‐index), decision curve analysis (DCA) as well as receiver operating characteristic (ROC) curve assisted in measuring the performance exhibited by the nomogram.

Results

We divided 381 PTC patients into the training cohort (n = 269) and the validation cohort (n = 112) randomly. Compared with patients who had a low stromal score, patients with a high stromal score appeared with significantly better PFS [Hazard ratio (HR) and 95% confidence interval (CI): 0.294, 0.130–0.664]. The C‐index of the PFS nomogram was 0.764 (0.662–0.866) in the training cohort and 0.717 (0.603–0.831) in the validation cohort. The calibration curves for PFS prediction in the nomogram were remarkably consistent with the actual observation. DCA indicated superior performance of the nomogram to predict PFS than the American Joint Committee on Cancer (AJCC) Tumor Node Metastasis (TNM) staging system. The ROC curves showed the favorable sensitivity and specificity of the novel nomogram.

Conclusion

High stromal score was significantly associated with improved PFS in patients with PTC. The nomogram based on the stromal score and clinicopathological patterns yielded a reliable performance to predict the prognosis of PTC.

Disease-free Survival of Patients with Differentiated Thyroid Cancer: A Study from a Tertiary Center in Oman

Objectives

As with global trends, the prevalence of differentiated thyroid cancer (DTC) has increased in recent years in Oman. However, to the best of our knowledge, no local studies have yet been published evaluating the prognosis of DTC cases in Oman. This study aimed to assess disease-free survival (DFS) and prognostic factors related to DTC among Omani patients attending a tertiary care center.

Methods

This retrospective, observational cohort study was conducted between January 2006 and May 2016 at the National Diabetes and Endocrine Center in Oman. Data related to DFS and prognostic factors were obtained from the electronic medical records of all ≥ 18-year-old patients diagnosed with DTC during the study period.

Results

A total of 346 DTC cases were identified. Overall, 82.7% of patients were disease-free at their last follow-up appointment. Univariate analysis indicated that various tumor characteristics including histological subtype (i.e., papillary carcinoma, Hurthle cell cancer, and minimally invasive follicular thyroid carcinoma), lymph node status, number of lymph node metastases, distant metastasis status, and TNM status (primary tumor (T), regional lymph node (N), distant metastasis (M) stage) were strong prognostic factors for DFS (p < 0.050). According to multivariate regression analysis, lymph node status, extrathyroidal extension, and angiovascular invasion were independent predictors of DFS (p < 0.050).

Conclusions

The overall prognosis of DTC among Omani patients was excellent. Treatment and follow-up strategies for patients with DTC should be tailored based on the individual’s risk factor profile.

A Comparison of the Seventh and Eighth Editions of the AJCC Staging Systems to Predict Recurrence in Papillary Thyroid Microcarcinoma

BACKGROUND

The incidence of papillary thyroid microcarcinoma has been constantly rising in recent decades. The tumor, node, metastasis staging system is designed to predict prognosis in patients with papillary thyroid carcinoma. Recent studies have shown that the American Joint Committee on Cancer (AJCC) 8th edition is superior to the 7th edition for predicting tumor recurrence in PTC patients. To date, whether the 8th edition is also better able to predict recurrence in papillary thyroid microcarcinoma (PTMC) remains unclear.

METHOD

We enrolled 1007 cases from our thyroid cancer database in the First Affiliated Hospital, Zhejiang University School of Medicine, from 1997 to 2011. Univariable and multivariate Cox hazard regression analyses were used to identify the association between variables and recurrence. Disease-free survival was calculated using the Kaplan-Meier method and compared using the log-rank test.

RESULTS

A total of 1007 PTMC patients were enrolled, with a median follow-up of 67 months. Of 93 (9.2%) patients downstaged by the changes in versions, 49 (52.7%) were downstaged because the age-at-diagnosis cut-off used for staging increased from 45 to 55 years, while 35 (37.6%) were downstaged due to the weakening of the effects of lymph node metastasis. The recurrence rate of PTMC was 4.17%. Univariate Cox hazards regression analyses showed that TNM stage according to the AJCC 8th edition was significantly associated with recurrence, while the recurrence survival curves showed that TNM stage (stage I vs. stage II-IV) according to the AJCC 8th edition, but not the 7th edition, was significantly associated with disease-free survival (p < 0.05).

CONCLUSIONS

The AJCC 8th edition has better ability to predict recurrence in PTMC patients than the 7th edition.

Lateral Lymph Node Metastases in T1a Papillary Thyroid Carcinoma: Stratification by Tumor Location and Size

OBJECTIVE

To analyze the incidence and risk factors for lateral lymph node metastases (LNMs) in T1a papillary thyroid carcinoma (PTC) with a focus on tumor location and size.

MATERIALS AND METHODS

The incidence of lateral LNM in 345 cases of T1a PTC was retrospectively analyzed. Univariate and multivariate analyses were performed to assess the relationships between lateral LNM and clinicopathological characteristics.

RESULTS

The incidence of skip metastasis to lateral LNM in T1a PTC located in the upper lobe was 12.1% (8/66). Logistic regression analysis indicated tumor size >5 mm (OR = 5.04, 95% CI = 1.79 to 14.18, P = 0.002), upper lobe location (OR = 7.68, 95% CI = 3.05-19.34, P < 0.001) and the number of central neck LNM (<2: OR = 24.79, 95% CI = 8.23-74.60, P < 0.001; ≥2: OR = 4.99, 95% CI = 1.95-12.73, P < 0.001) were independently associated with lateral LNM. Comparing the lateral and central LNM stratification based on tumor location revealed that both the incidences of lateral (33.3%) and central (30.3%) LNM of T1a PTC located in the upper lobe were higher than those of T1a PTC located in the middle and lower lobes. Of T1a PTC located in the upper lobe, the incidence of lateral LNM was 33.3% (22/66), which was higher than that [30.3% (20/66)] of central LNM. This finding is reversed in all T1a PTC cases and T1a PTC cases with tumor located in the middle and lower lobes.

CONCLUSION

A particularly high likelihood of lateral LNM was observed in T1a PTC patients with tumor located in the upper lobe of the thyroid gland, especially the tumor >5 mm in size, which could be considered a risk factor for lateral LNM in the clinical management of T1a PTC.

Correlation of ThyroSeq Results with Surgical Histopathology in Cytologically Indeterminate Thyroid Nodules

The ThyroSeq next-generation sequencing test refines the risk of malignancy in cytologically indeterminate thyroid nodules. Specific genetic alterations have distinct cancer probabilities and clinical phenotypes. There is limited data on the association between specific genetic alterations and histopathologic features. The aim of this study was to evaluate specific ThyroSeq alterations in prognosticating high-risk histopathologic characteristics. We performed a retrospective single-institution study of all patients diagnosed with indeterminate thyroid nodules (May 2016-December 2019) who had a mutation identified with ThyroSeq v2 or v3 and underwent surgical resection. Specific genetic alterations were correlated with surgical histopathology. The main outcomes were risk of malignancy and structural recurrence risk based on histopathologic features and the 2015 American Thyroid Association (ATA) risk stratification. Of the 78 nodules, 50 (64%) were thyroid cancer or noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) on surgical histopathology. Nodules with high-risk TERT or TP53 combination mutations (TERT/TP53) and those with BRAF-like mutations were associated with a 100% probability of cancer and higher rates of extrathyroidal extension and regional nodal involvement than nodules with RAS-like mutations. Among nodules with RAS-like mutations, there was an even distribution between benign, NIFTP, and malignant results, the latter of which were all ATA low risk for structural disease recurrence. Overall, TERT/TP53 and BRAF-like ThyroSeq mutations are associated with an increased cancer probability and risk of recurrence defined by histopathologic features, while RAS-like mutations are associated with lower cancer probability and indolent disease. Individualized management, including extent of surgery, should be considered based on specific genetic alterations found in cytologically indeterminate thyroid nodules.

Oncologic and functional outcomes following laryngectomy for locally advanced thyroid cancer

BACKGROUND AND OBJECTIVES

Total laryngectomy in thyroid cancer is controversial. Functional and oncologic outcomes are needed to inform surgical indications in this population.

METHODS

A retrospective cohort study was performed at a tertiary referral center from 1997 to 2018 to identify patients with a diagnosis of thyroid carcinoma who underwent total laryngectomy. Complications, survival outcomes, and functional outcomes were analyzed.

RESULTS

Thirty patients met the inclusion criteria. The mean age was 62 years (range, 30-88 years) and the male-to-female ratio was 1:2.75. The most common diagnosis was well-differentiated thyroid cancer (53.3%), followed by poorly differentiated (30%) and anaplastic (16.7%). Total laryngectomy was performed with a 10% rate of Clavien-Dindo Grade III-V complications. The median overall survival was 40 months (range, 1-237). Five-year overall survival was 39.5% and disease-specific survival was 51.1%. Locoregional control was achieved in 80.0% of patients. Twelve months postoperatively, 100% of surviving patients were taking oral intake and 86.4% had a self-reported functional voice.

CONCLUSION

Total laryngectomy for locally advanced thyroid cancer is safe and provides acceptable rates of locoregional control. While the risk of distant metastases remains high, advances in systemic therapy may justify aggressive local control strategies to improve the quality of life.

Are Bethesda III Thyroid Nodules More Aggressive than Bethesda IV Thyroid Nodules When Found to Be Malignant?

The Bethesda classification system for thyroid fine needle aspirate (FNA) is used to predict the risk of malignancy and to guide the management of thyroid nodules. We postulated that thyroid malignancies characterized as Bethesda III on FNA have more aggressive features than those classified as Bethesda IV. A retrospective chart review was performed to identify those who underwent thyroid surgery at a single tertiary hospital setting between 2015 and 2020. Associations between Bethesda category, molecular genetic test results, and histopathologic findings were examined. Out of 628 surgeries that were performed, 199 (54.2%) Bethesda III nodules and 216 (82.8%) Bethesda IV nodules were malignant. Of those that were malignant, 37 (18.6%) and 22 (10.2%) Bethesda III and Bethesda IV nodules showed aggressive features, respectively (p value = 0.014). There was a proportionally increased number of aggressive features in extra-thyroidal extension, lymph nodes metastasis, and all aggressive subtypes of papillary thyroid cancer in the Bethesda III category. Although Bethesda IV nodules are much more likely to be malignant (p value = 0.002), our study suggests that Bethesda III nodules that are resected are more likely to have aggressive features than Bethesda IV nodules, with a statistically significant increase in the solid variant of papillary thyroid cancer and lymph node metastasis.

Preoperative Factors Associated with Extrathyroidal Extension in Papillary Thyroid Cancer

OBJECTIVE

Extrathyroidal extension may not be accurately recognized during thyroidectomy and can increase the risk of positive margins and even recurrence. This study aimed to investigate the preoperative factors associated with extrathyroidal extension.

METHODS

We analyzed 887 patients with papillary thyroid cancer (PTC) who underwent surgery in the period of 2005-2017. Binary logistic regression analyses and generalized additive models were used to identify associations.

RESULTS

Minimal extrathyroidal extension was present in 233 (26%) patients and advanced extrathyroidal extension was found in 60 (7%) patients. Age, BMI, and tumor size were independent predictors of all or advanced extrathyroidal extension. Among the 493 patients whose BRAF mutation status was available, age (OR = 1.025), BMI (OR = 1.091), tumor size (OR = 1.544), and BRAF V600E mutation (OR = 2.311) were independently associated with extrathyroidal extension.

CONCLUSIONS

Older age, a greater BMI, a larger tumor size, and presence of the BRAF mutation were predictive of extrathyroidal extension. These factors should be taken into consideration in decision-making before surgery is performed.

Extrathyroidal extension predicts negative clinical outcomes in papillary thyroid cancer

BACKGROUND

The eighth edition American Joint Committee on Cancer tumor-node-metastasis staging for well-differentiated thyroid cancers, no longer considers "minimal" extrathyroidal extension for tumor staging. This change prompted us to examine the effect of extrathyroidal extension on patient outcomes.

METHODS

Patients (n = 177,497) in the 2016 National Cancer Database with classic papillary thyroid cancer were evaluated to determine the effect of extrathyroidal extension on overall survival and risk for nodal and distant metastases. Kaplan-Meier curves with the log-rank test were used to evaluate survival differences. Multivariable Cox and logistic regression analyses included relevant clinicopathologic variables (e.g. age, sex, race, and Charlson Comorbidity Index).

RESULTS

Patients with "minimal" extrathyroidal extension had worse survival versus patients with no extrathyroidal extension (10-year survival 89.3% vs 93.1%, hazard ratio 1.23; 95% confidence interval, 1.13-1.35; P < .001). Any extrathyroidal extension was associated with higher risks for lymph node (odds ratio 2.78; 95% confidence interval, 2.69-2.87) and distant metastasis (odds ratio 3.5; 95% confidence interval, 3.05-4.04). These associations persisted when comparing "micro" (extension into the thyroid capsule) versus none for nodal risk (odds ratio 1.25; 95% confidence interval, 1.18-1.33) and distant metastasis (OR 1.52; 95% confidence interval, 1.11-2.09).

CONCLUSION

All levels of extrathyroidal extension, including microscopic, were associated with increased risk for nodal and distant metastasis. Both minimal and macroscopic extrathyroidal extension were also associated with decreased overall survival. Such findings have the potential to affect the clinical decision making for patients diagnosed with papillary thyroid cancer.

Extrathyroidal Extension is an Important Predictor of Regional Lymph Node Metastasis in Pediatric Differentiated Thyroid Cancer

Introduction: The American Joint Committee Cancer (AJCC) TNM system predicts survival in patients with differentiated thyroid cancer (DTC). In the eighth edition of the AJCC TNM, microscopic extrathyroidal extension (microETE) was removed and tumor size >4 cm was maintained in the definition of T3 disease to reduce unnecessarily aggressive therapy for adults at low risk of death from DTC. In pediatric patients where DTC survival rates are high, the AJCC TNM is used to identify patients at increased risk of persistent, postsurgical disease, to identify patients who benefit from radioactive iodine therapy. The aim of this study was to assess the correlation of microETE with cervical lymph node (LN) metastasis in pediatric patients and to determine if tumor size or microETE is more informative in predicting regional LN disease. Methods: Patients with DTC <19 years of age at the time of thyroidectomy with AJCC T3 tumors (seventh edition) and the presence of LNs on the surgical specimen were included in this retrospective chart review. Pathological findings were confirmed by pathologist review. Results: Forty-five patients with AJCC T3 designation were included, 34 with microETE and 11 without microETE. Of those with microETE, 32 (94.1%) demonstrated regional LN metastasis compared with 5/11 patients (45.5%) without microETE (p = 0.001). In addition, microETE was associated with lateral neck LN metastasis (p = 0.004), bilateral disease (p = 0.001), and tumor multifocality (p = 0.003). Patients with microETE had smaller tumors (median = 2.5 cm, interquartile range [IQR]: 1.6-4.5) compared with patients without microETE (median = 5 cm, IQR: 4.2-5.4; p = 0.02). No increased association was found between microETE and vascular invasion, distant metastasis, or persistent/recurrent disease. Conclusions: In pediatric patients with DTC, microETE is a strong predictor of LN metastasis when compared with tumor size. For patients who do not undergo prophylactic central neck LN dissection, the presence of microETE predicts an increased risk of postsurgical disease and should be included in future revisions of the American Thyroid Association pediatric risk stratification categories.

Prevalence and Risk of Metastatic Thyroid Cancers and Management Outcomes: A National Perspective

OBJECTIVES

Examine the prevalence and risk of metastasis in thyroid cancers and management outcomes.

STUDY DESIGN

Retrospective analysis of the National Cancer Database, 2004-2014.

METHODS

The study population included adult (≥ 18 years) patients with thyroid cancer. Analysis included multivariate logistic regression and Cox hazard ratio modeling.

RESULTS

A total of 152,979 patients were included. Distant metastasis was reported in 1,867 (1.22%) patients. The distribution of metastatic cases based on pathology and tumor size were as follows in descending order: papillary thyroid carcinoma (PTC) 1 to 4 cm (30.53%), PTC > 4 cm (19.34%), undifferentiated (UTC) > 4 cm (14.14%), PTC < 1 cm (8.46%), follicular thyroid carcinoma (FTC) > 4 cm (7.28%), FTC 1 to 4 cm (5.52%), medullary thyroid cancer (MTC) ≤ 4 cm (3.96%), MTC > 4 cm (3.91%), UTC ≤ 4 cm (3.32%), Hürthle (HCC ) > 4 cm (2.09%), and HCC 1 to 4 cm (1.45%). Significant predictors of distant metastasis, while controlling for tumor pathology and size, included older age, male gender, non-White minorities, presence of multiple comorbidities, minimal, gross extrathyroidal extension (ETE), lymphovascular invasion (LVI), and concomitant central and lateral lymph node metastasis (LNM) (P < .05 each). The risk of distant metastasis in the absence of nodal metastasis, ETE, and LVI was highest for FTC > 4 cm.

CONCLUSION

Although the risk of metastasis in well-differentiated thyroid carcinoma (WDTC) is low, the prevalence of metastatic thyroid cancer is highest in WDTC population because it is the most common type of thyroid cancer. Certain pathological features, including minimal ETE and central LNM, are associated with a higher prevalence of metastatic disease.

LEVEL OF EVIDENCE

NA Laryngoscope, 131:237-244, 2021.

Risk Factors for Lymph Node Metastasis in Papillary Thyroid Carcinoma: A Systematic Review and Meta-Analysis

Purpose: To explore the risk factors that may predict the lymph node metastasis potential of these lesions and new prevention strategies in papillary thyroid carcinoma patients. Materials and Methods: In total, 9,369 papillary thyroid carcinoma patients with 37.17% lymph node metastasis were analyzed (Revman 5.3 software) in this study. The PubMed and Embase databases were used for searching works systematically that were published through to January 22, 2020. Results: Several factors were related to the increased risk of lymph node metastasis in patients with papillary thyroid carcinoma: age <45 years (pooled OR = 1.52, 95% CI = 1.14-2.01, p <0.00001); gender = male (pooled OR = 1.68, 95% CI = 1.51-1.87, p <0.00001); multifocality (pooled OR = 2.05, 95% CI = 1.45-2.89, p <0.0001); tumor size ≥1.0 cm (pooled OR = 3.53, 95% CI = 2.62-4.76, p <0.00001); tumor location at the upper pole 1/3 (pooled OR =1.46, 95% CI = 1.04-2.04, p = 0.03); capsular invasion + (pooled OR = 3.48, 95% CI = 1.69-7.54, p = 0.002); and extrathyroidal extension + (pooled OR = 2.03, 95% CI= 1.78-2.31, p <0.00001). However, tumor bilaterality (pooled OR = 0.85, 95% CI = 0.54-1.34, p = 0.49) and Hashimoto's thyroditis (pooled OR = 1.08, 95% CI = 0.79-1.49, p = 0.62) showed no correlation with lymph node metastasis in papillary thyroid carcinoma patients. Conclusion: The systematic review and meta-analysis defined several significant risk factors of lymph node metastasis in papillary thyroid cancer patients: age (<45 years), gender (male), multifocality, tumor size (>1 cm), tumor location (1/3 upper), capsular invasion, and extra thyroidal extension. Bilateral tumors and Hashimoto's thyroiditis were unrelated to lymph node metastasis in patients with papillary thyroid cancer.

Risk Factors and Outcomes of Postoperative Recurrent Well-Differentiated Thyroid Cancer: A Single Institution's 15-Year Experience

OBJECTIVE

Identify risk factors and outcomes of recurrent well-differentiated thyroid cancer.

STUDY DESIGN

Retrospective case-control analysis.

SETTING

Tertiary care academic center in Nashville, Tennessee.

SUBJECTS AND METHODS

This single-center analysis reviews 478 patients who underwent initial surgical management of well-differentiated thyroid carcinoma between 2002 and 2017. Patients were dichotomized with or without recurrent well-differentiated thyroid cancer. Demographic and clinicopathologic risk factors were carefully reviewed. Univariate, multiple regression, and survival analyses were used to evaluate predictors of recurrence.

RESULTS

Thirty-eight patients (7.9%) who received initial surgical intervention for well-differentiated thyroid carcinoma at our institution recurred, with an average time to recurrence of 24 months. Male sex, tumor size, multifocality, extrathyroidal extension, lymphovascular invasion, number of positive lymph nodes, and low lymph node yield were all significantly associated with locoregional recurrence (P < .05). Multiple regression analysis showed that extrathyroidal extension, number of positive lymph nodes, and low lymph node yield were independent factors predictive of posttreatment recurrence (P < .05). Metastatic lymph node ratio, the ratio of positive lymph nodes extracted to lymph node yield, of ≥0.3 is associated with increased risk of recurrence (P < .001) and decreased 5-year recurrence free survival (P < .001).

CONCLUSION

Extrathyroidal extension, number of positive lymph nodes, and low lymph node yield are independent clinicopathologic risk factors for postoperative recurrence of well-differentiated thyroid cancer. Metastatic lymph node ratio is uncommonly used but can be an important prognosticator of recurrence. Patients with metastatic lymph node ratio ≥0.3 should be counseled on their increased risk of recurrence and should undergo close surveillance following surgery.

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.

Risk factors for posttreatment recurrence in patients with intermediate-risk papillary thyroid carcinoma

BACKGROUND

Papillary thyroid carcinoma (PTC) is generally associated with favorable outcomes; however, intermediate-risk requires further evaluation. We therefore examined risk factors for posttreatment recurrence in patients with intermediate-risk PTC.

METHODS

This study involved 1782 patients who underwent thyroidectomy for intermediate-risk PTC. Univariate and multivariate Cox proportional hazard regression analyses were used to identify the significant factors predictive of posttreatment recurrence-free survival (RFS).

RESULTS

Of intermediate-risk factors, univariate analyses showed that clinical and pathological cervical lymph node (LN) positivity (cN1 and pN1), aggressive histology, and multifocality with microscopic extrathyroidal extension were significantly associated with RFS outcomes (all P < 0.05). In multivariate analyses, cN1, >5 pN1, and posttreatment radioactive iodine (RAI)-avid metastatic foci of intermediate risk remained the independent factors predictive of RFS (all P < 0.05). The combination of any three or more of these intermediate-risk factors appeared to increase the posttreatment recurrence rate.

CONCLUSION

Clinical nodal positivity, the number of positive LNs, and the presence of RAI-avid metastatic foci in the ATA intermediate-risk category might independently decrease RFS in patients with intermediate-risk PTC.

Implications of Extrathyroidal Extension Invading Only the Strap Muscles in Papillary Thyroid Carcinomas

Background: Based on the new TNM classification, differentiated thyroid carcinomas with extrathyroidal extension (ETE) into the strap muscles are designated as T3b. The current study analyzed the clinical significance of this new stage in patients with papillary thyroid cancer (PTC). Subjects and Methods: This retrospective cohort study included 4045 eligible PTC patients. The patients were divided into four groups according to the extent of ETE: no ETE, ETE into perithyroidal tissue, T3b (ETE into the strap muscles), and ETE beyond the strap muscles. Differences in the clinical characteristics and prognosis of the four groups were assessed. Results: Of these 4045 patients, 2300 (56.9%) had no ETE, 1004 (24.8%) had ETE into perithyroidal tissue, 371 (9.2%) had ETE into the strap muscles, and 370 (9.1%) had ETE beyond the strap muscles. Tumor size, multifocality, lymph node metastasis (LNM), distant metastasis (DM), recurrence, and recurrence-free survival (RFS) between patients with ETE into perithyroidal tissue and patients without ETE did not show differences, but significant differences were observed between patients with T3b and patients without ETE, and only patients with ETE beyond the strap muscles had significantly worse overall survival (OS) than the other three groups. However, T3b did not independently predict worse RFS in univariable and multivariable analyses. Conclusions: T3b, distinguished from minimal ETE, may be related to larger tumor size, higher prevalence of multifocality, LNM, DM, recurrence, and worse RFS than no ETE, but it may not affect OS and may not independently predict recurrence in PTC patients.

Unexpected high-risk pathologic features following thyroidectomy in the chinese immigrant population

OBJECTIVE

To compare rates of unexpected high-risk pathologic features between Chinese and non-Asian patients who underwent thyroidectomy for papillary thyroid cancer.

METHODS

This was a retrospective cohort study at a tertiary academic urban medical center. Patients who underwent thyroidectomy for papillary carcinoma from 2015 to 2017 were included. Patient demographics, tumor characteristics, and tumor histopathology were analyzed. Primary outcome was the presence of adverse histopathologic features such as lymphovascular invasion (LVI) or microscopic/minimal extrathyroidal extension (mETE). Differences between the groups were analyzed using multivariate logistical regression analysis and propensity score-weighted analysis.

RESULTS

One hundred seventy-nine patients were included: 58 Chinese-born and 121 non-Asian. The median age of the cohort was 47 years old (36-58). Twenty-nine percent of patients were male, and 71% were female. There was no statistically significant difference between the two cohorts in rates of LVI, multifocality, extent of surgery, or presence of thyroiditis. Patients with mETE were more likely to have larger tumors (P = 0.00247). Both the multivariate and propensity-weighted models demonstrated that Chinese ancestry was independently associated with an increased rate of unexpected mETE (adjusted prevalence ratio, 2.52; 95% confidence interval, 1.82-3.48).

CONCLUSION

mETE is significantly higher in the immigrant Chinese compared to the non-Asian population. Given the high prevalence of unexpected mETE in the Chinese population, the added risk of this finding should be brought into the discussion during initial surgical planning.

LEVEL OF EVIDENCE

3 Laryngoscope, 130:1844-1849, 2020.

Risk of Recurrence in Differentiated Thyroid Cancer: A Population-Based Comparison of the 7th and 8th Editions of the American Joint Committee on Cancer Staging Systems

BACKGROUND

Differentiated thyroid cancer (DTC) survival is excellent, making recurrence a more clinically relevant prognosticator. We hypothesized that the new American Joint Committee on Cancer (AJCC) 8th edition improves on the utility of the 7th edition in predicting the risk of recurrence in DTC.

METHODS

A population-based retrospective review compared the risk of recurrence in patients with DTC according to the AJCC 7th and 8th editions using the Surveillance, Epidemiology, and End Results-based Kentucky Cancer Registry from 2004 to 2012.

RESULTS

A total of 3248 patients with DTC were considered disease-free after treatment. Twenty percent of patients were downstaged from the 7th edition to the 8th edition. Most patients had stage I disease (80% in the 7th edition and 94% in the 8th edition). A total of 110 (3%) patients recurred after a median of 27 months. The risk of recurrence was significantly associated with stage for both editions (p < 0.001). In the 7th edition, there was poor differentiation between lower stages and better differentiation between higher stages (stage II hazard ratio [HR] 0.91, 95% confidence interval [CI] 0.39-2.11; stage III HR 3.72, 95% CI 2.29-6.07; stage IV HR 11.66, 95% CI 7.10-19.15; all compared with stage I). The 8th edition better differentiated lower stages (stage II HR 4.06, 95% CI 2.38-6.93; stage III HR 13.07, 95% CI 5.30-32.22; stage IV 11.88, 95% CI 3.76-37.59; all compared with stage I).

CONCLUSIONS

The AJCC 8th edition better differentiates the risk of DTC recurrence for early stages of disease compared with the 7th edition. However, limitations remain, emphasizing the importance of adjunctive strategies to estimate the risk of recurrence.

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-oriented concept of treatment for intrathyroid papillary thyroid cancer

Adapting treatment and follow-up according to the risk of recurrence and/or death from thyroid cancer is a relatively recent concept of "personnalized" medicine, developed particularly to avoid overtreatment of low-risk thyroid cancer which represents the majority of thyroid cancers diagnosed in the world today. For low-risk thyroid cancer, this decrease in extent of treatment involves the extent of surgery-total thyroidectomy, lobectomy or no surgery with active surveillance-but also the indications, doses and methods of stimulation when or if administering radioactive iodine (RAI), the indication for suppressive thyroxin therapy and the extent and modalities for follow-up that should be adapted to the risk of recurrence. The aim is to optimize medical resources and quality of life, particularly for low-risk patients whose life expectancy is that of the general population.

Predictors for central lymph node metastases in CN0 papillary thyroid microcarcinoma (mPTC): A retrospective analysis of 1304 cases

BACKGROUND

Presence of lymph node metastases increases the risk of recurrence, but prophylactic central neck node dissection for patients with micropapillary thyroid cancer (mPTC) is controversial. We aim to find the clinical predictors of central lymph node metastases (CLNM) in patients with cN0 mPTC.

METHODS

We retrospectively reviewed the clinicopathological and molecular genetic characteristics of 1304 patients with cN0 mPTC operated at the First Hospital of Jilin University between January 1, 2013 and May 31, 2016, all underwent thyroid lobectomy or total thyroidectomy with unilateral or bilateral prophylactic central neck dissection. Univariate and multivariate analysis were used to identify the predictors of CLNM.

RESULTS

30.7% of cN0 mPTC patients had CLNM. Univariate analysis found CLNM to be associated with younger age (≤45), male gender, larger tumor (>0.5 cm), multifocality, bilaterality, capsular invasion, lymphovascular invasion and extrathyroidal infiltration, but not associated with BRAF mutation, tumor location, preoperative TSH and anti-thyroglobulin antibody level. Multivariate logistic regression showed age ≤45 years (p < 0.001, OR = 2.05), male gender (p < 0.001, OR = 1.94), tumor size >0.5 cm (p < 0.001, OR = 1.87), bilaterality (p = 0.003, OR = 1.86) and capsular invasion (p = 0.013, OR = 1.49) to be independent predictors for CLNM in cN0 mPTC patients.

CONCLUSIONS

Prophylactic central neck dissection has higher yield for cN0 mPTC patients with age ≤45 years, male gender, tumor size>0.5 cm, bilaterality and capsular invasion. BRAF mutation is not a predictor for CLNM in cN0 mPTC patients.

An Analysis of The American Joint Committee on Cancer 8th Edition T Staging System for Papillary Thyroid Carcinoma

BACKGROUND

The American Joint Committee on Cancer (AJCC) removed microscopic extrathyroidal extension (ETE) from the 8th edition T staging for papillary thyroid cancer (PTC) based on increasing evidence that it is not an independent prognostic factor.

OBJECTIVES

We compared the prognostic performance of AJCC 7th (pT7) and 8th (pT8) edition T stage systems, particularly in patients ≥55 years old without macroscopic ETE or distant metastases in whom T classification affects AJCC Tumor Node Metastasis (TNM) stage.

METHOD

A retrospective analysis of disease-free survival (DFS) in 577 patients with PTC comparing pT8 vs pT7 using the Akaike information criterion (AIC), Harrell's C-index, and Proportion of Variation Explained (PVE).

RESULTS

Of 105 patients with AJCC7 T3 disease, 74 were down-staged. Overall, the prognostic performance of pT7 and pT8 was similar. However, in patients ≥55 years old without macroscopic ETE or distant metastases, pT8 was inferior to pT7 on the basis of higher AIC, lower C-index (0.67 vs 0.76), and lower PVE (30% vs 45%). In this subset, microscopic ETE was associated with multiple other adverse prognostic features and reduced DFS (hazard ratio, 2.8; 95% confidence interval, 1.5 to 5.2; P = 0.002), irrespective of tumor size.

DISCUSSION

In our cohort, pT8 was inferior to pT7 in patients ≥55 years old without macroscopic ETE or distant metastases in whom T classification affects TNM stage. Microscopic ETE was strongly associated with other adverse prognostic factors and reduced DFS in this patient subgroup and may be an effective surrogate for disease biology in PTC, irrespective of whether it is an independent prognostic factor.

Prognostic significance of gross extrathyroidal extension invading only strap muscles in differentiated thyroid carcinoma

Background

In the eighth edition of the AJCC staging system for differentiated thyroid carcinoma (DTC), minimal extrathyroidal extension (ETE) is no longer a determinant of T3 category. Instead, gross ETE invading only strap muscles has been designated as a new T3b category. The long-term prognosis of patients with DTC and gross ETE invading only strap muscles was investigated.

Methods

This was a retrospective analysis of patients who underwent thyroidectomy between 1996 and 2005. Differences in cancer-specific and recurrence-free survival according to extent of ETE were assessed.

Results

A total of 3174 patients with DTC were included. No significant differences were observed in 10-year cancer-specific survival among patients with no ETE (98·6 per cent), microscopic ETE (98·3 per cent) and gross ETE invading only strap muscles (98·9 per cent) (P = 0·375). The 10-year recurrence-free survival rate for patients with gross ETE invading only strap muscles (89·2 per cent) was shorter than that for patients with no ETE (93·7 per cent; P = 0·016), but similar to that of patients with microscopic ETE (90·3 per cent). In univariable analysis, patients with gross ETE invading only strap muscles had a significantly higher risk of recurrence than those with no ETE (hazard ratio (HR) 1·67, 95 per cent c.i. 1·10 to 2·55; P = 0·017). In multivariable analysis, gross ETE invading only strap muscles was not an independent predictor of recurrence (HR 1·09, 0·71 to 1·69; P = 0·685).

Conclusion

Although gross ETE invading only strap muscles may provide prognostic information about long-term recurrence, it does not affect mortality. The actual impact of gross ETE invading only strap muscles will be important in revising the staging system in the future.

Occult invasion of sternothyroid muscle by differentiated thyroid cancer

PURPOSE

To determine the incidence of occult invasion of sternothyroid by differentiated thyroid cancer (DTC) and identify clinico-pathological features associated with the same.

METHODS

Retrospective study of a consecutive series of DTC patients undergoing surgery, with preoperative ultrasound showing no evidence of strap muscle invasion. All had en bloc excision of sternothyroid muscle along with thyroidectomy. Incidence of microscopic invasion of sternothyroid and clinicopathologic features associated with the same, were studied.

RESULTS

A total of 76 patients with DTC (2010-2014) were identified, of whom 62 met the inclusion criteria and were included in this study. Of these, 22 (36%) had no extrathyroidal extension (ETE), 30 (48%) had minimal ETE without sternothyroid invasion and 10 (16%) had minimal ETE with microscopic sternothyroid invasion. The mean tumor sizes of the three sub-groups were 1.9, 3.1 and 4.9 cm, respectively, with a significant difference between no ETE and sternothyroid invaded sub-groups (p = 0.03). Out of the 40 cases with minimal ETE, 3 (7.5%) had positive tumor microscopic margin. Retaining sternothyroid in situ would have theoretically increased this proportion to 27.5%. Over a median follow-up of 52 months, 58 (94%) patients remained structurally disease free, with only 1 local recurrence.

CONCLUSION

Occult invasion of sternothyroid muscle occurred in 16% of DTC in this series. Excision of the muscle en bloc with thyroidectomy, particularly in larger tumors, may confer benefit in accurately staging the disease, encompassing occult ETE and achieving clear microscopic margins.