Minimal extrathyroid extension does not affect the relapse-free survival of patients with papillary thyroid carcinoma measuring 4 cm or less over the age of 45 years

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.

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.

[Hemithyroidectomy or total thyroidectomy for low-risk papillary thyroid cancer? : Surgical criteria for primary and secondary choice of treatment in an interdisciplinary treatment concept]

The increase in small intrathyroid papillary thyroid cancer (PTC) observed worldwide over the past two decades, with no increase in cancer-specific mortality, has challenged the previous concept of total thyroidectomy as a one-size-fits-all panacea. After exclusion of papillary microcarcinomas, a systematic review of 20 clinical studies published since 2002, which compared hemithyroidectomy (HT) to total thyroidectomy (TT), found comparable long-term oncological outcomes for low-risk papillary thyroid cancer (LRPTC) 1-4 cm in diameter, whereas postoperative complication rates were markedly lower for HT. To refine individual treatment plans, HT should be combined with ipsilateral central lymph node dissection and intraoperative frozen section analysis for staging. Based on recent evidence from studies and in consideration of individual risk factors, patients with LRPTC can be offered the concept of HT as an alternative to the standard TT. A prerequisite for the treatment selection and decision is a comprehensive patient clarification of the possible advantages and disadvantages of both approaches.

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

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

Clinical Significance of Tumor Size in Gross Extrathyroidal Extension to Strap Muscles (T3b) in Papillary Thyroid Carcinoma: Comparison with T2

The purpose of the present study was to compare the risk of recurrence between T2 and T3b papillary thyroid carcinoma (PTC) and the effect of tumor size on survival in T3b disease. A total of 634 patients with PTC who underwent thyroid surgery at a single center were retrospectively analyzed. Clinicopathological characteristics were compared according to the T category in the TNM staging system, with T3b divided into T3b-1 (tumor size, ≤2 cm) and T3b-2 (tumor size, 2–4 cm). Disease-free survival (DFS) and recurrence risk were compared between T2, T3b, T3b-1, and T3b-2. Tumor size was significantly larger in T2 than in T3b. A significant difference in recurrence was observed between T2 and T3b-2 but not between T2 and T3b-1. T3b-2 was identified as a significant risk factor for PTC recurrence. A significant difference in the DFS curve was observed between T2 and T3b-2. However, no significant differences in survival were observed between T2 and T3b or T3b-1. These results indicate that the prognostic impact of T3b may vary depending on tumor size. Further studies are required to determine the need for T classifications that account for tumor size and gETE invasion of the strap muscles.

Differences in the clinical characteristics of papillary thyroid microcarcinoma located in the isthmus ≤5 mm and >5mm in diameter

Background

The optimal treatment of papillary thyroid microcarcinomas (PTMCs) located in the isthmus (iPTMCs) is still controversial. The purpose of this study was to compare the clinicopathologic features of patients with iPTMCs ≤5 mm and >5 mm in diameter after total thyroidectomy, and to identify the risk factors for recurrence in patients with iPTMCs.

Methods

A total of 102 iPTMC patients who underwent total thyroidectomy were reviewed retrospectively. The clinicopathologic characteristics of iPTMCs ≤5 mm group (n = 29) have been compared with a group >5 mm (n = 73). Univariate and multivariate Cox proportional hazard models served to identify risk factors associated with recurrence-free survival (RFS).

Results

Gender (p = 0.033), multifocality (p = 0.041), and central lymph node metastasis (CLNM) (p = 0.009) of patients in the ≤5 mm and >5 mm groups differed significantly. iPTMC patients with age <55 years, male, multiple tumor, and extrathyroidal extension showed comparatively more frequent of CLNM in >5 mm groups. Of the 102 patients, nine (8.8%) developed recurrence during follow-up (median: 49.5 months). The patients with recurrences had comparatively high rates of CLNM (p = 0.038), extranodal invasion (p = 0.018), and more MNCND (Metastasis Nodes for Central Neck dissection) (p = 0.020). A cutoff of MNCND >2.46 was established as the most sensitive and specific level for the prediction of recurrence based on receiver operating characteristic (ROC) curve analyses. Multivariate analysis showed that the number of MNCND ≥3 was an independent predictor of poor RFS (p = 0.028).

Conclusion

We have found that the recurrence rates are similar in patients with iPTMCs ≤5 mm and >5 mm. The iPTMCs >5 mm were more likely to be associated with pathological features such as multifocality and CLNM. The male gender, extrathyroidal extension, and CLNM were associated with recurrence of iPTMCs except for tumor size and multifocality. Higher risk of CLNM should be considered in iPTMC >5 mm when it reaches some risk factors. The numbers of MNCND ≥3 may be an independent predictor for recurrence, which could help clinicians for the decision of radioiodine administration and the modulation of follow-up modalities.

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

Background

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

Methods

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

Results

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

Conclusions

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

Minimal Extrathyroidal Extension in Predicting 1-Year Outcomes: A Longitudinal Multicenter Study of Low-to-Intermediate-Risk Papillary Thyroid Carcinoma (ITCO#4)

Background: The role of minimal extrathyroidal extension (mETE) as a risk factor for persistent papillary thyroid carcinoma (PTC) is still debated. The aims of this study were to assess the clinical impact of mETE as a predictor of worse initial treatment response in PTC patients and to verify the impact of radioiodine therapy after surgery in patients with mETE. Methods: We reviewed all records in the Italian Thyroid Cancer Observatory database and selected 2237 consecutive patients with PTC who satisfied the inclusion criteria (PTC with no lymph node metastases and at least 1 year of follow-up). For each case, we considered initial surgery, histological variant of PTC, tumor diameter, recurrence risk class according to the American Thyroid Association (ATA) risk stratification system, use of radioiodine therapy, and initial therapy response, as suggested by ATA guidelines. Results: At 1-year follow-up, 1831 patients (81.8%) had an excellent response, 296 (13.2%) had an indeterminate response, 55 (2.5%) had a biochemical incomplete response, and 55 (2.5%) had a structural incomplete response. Statistical analysis suggested that mETE (odds ratio [OR] 1.16, p = 0.65), tumor size >2 cm (OR 1.45, p = 0.34), aggressive PTC histology (OR 0.55, p = 0.15), and age at diagnosis (OR 0.90, p = 0.32) were not significant risk factors for a worse initial therapy response. When evaluating the combination of mETE, tumor size, and aggressive PTC histology, the presence of mETE with a >2 cm tumor was significantly associated with a worse outcome (OR 5.27 [95% confidence interval], p = 0.014). The role of radioiodine ablation in patients with mETE was also evaluated. When considering radioiodine treatment, propensity score-based matching was performed, and no significant differences were found between treated and nontreated patients (p = 0.24). Conclusions: This study failed to show the prognostic value of mETE in predicting initial therapy response in a large cohort of PTC patients without lymph node metastases. The study suggests that the combination of tumor diameter and mETE can be used as a reliable prognostic factor for persistence and could be easily applied in clinical practice to manage PTC patients with low-to-intermediate risk of recurrent/persistent disease.

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

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

Genetic Alterations in Pediatric Thyroid Cancer Using a Comprehensive Childhood Cancer Gene Panel

CONTEXT

Pediatric differentiated thyroid cancer (DTC) differs from adult DTC in its underlying genetics and clinicopathological features. In this report, we studied these aspects in 48 cases of pediatric DTC.

PATIENTS AND METHODS

We used the comprehensive Oncomine Childhood Cancer Gene panel on Ion Torrent next-generation sequencing platform. We included 48 patients (37 girls and 11 boys) with pediatric DTC (median age 17 years; range, 5-18 years) and studied the association between these genetic alterations and the clinicopathological features and outcome.

RESULTS

Of 48 tumors, 33 (69%) had somatic genetic alterations that were mutually exclusive except in one tumor. BRAFV600E and RET-PTC1 were the most common, occurring in 9 different tumors (19%) each. RET-PTC3 and ETV6-NTRK3 were the next most common, with each occurring in 4 different tumors (8%). Other genetic alterations including EML4-NTRK1, EML4-ALK, NRAS, KRAS, PTEN, and CREBBP occurred once each. There were no differences between those who had mutations and those without mutations with respect to age, sex, tumor multifocality, extrathyroidal extension, vascular invasion, lymph node or distant metastasis, and American Thyroid Association response to therapy status at the last follow-up visits. Similarly, none of these factors was different between those with fusion genes vs single-point mutations vs no mutations.

CONCLUSIONS

In pediatric DTC, fusion genes are more common than single-point mutations. The most common genetic alterations are RET-PTC1, BRAFV600E, RET-PTC3, and ETV6-NTRK3. Other alterations occur rarely. Genetic alterations do not correlate with the clinicopathological features or the outcome.

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

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

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.

Microscopic extrathyroid extension in papillary thyroid carcinoma: impact on response to therapy

Objectives Evaluate the impact of microscopic extrathyroid extension (MEE) on outcome and therapy response in patients with cT1 and cT2 papillary thyroid carcinoma (PTC). Subjects and methods Retrospective study of 970 consecutive patients, who underwent surgery for PTC between 2000 and 2016. All patients had: tumours ≤ 4 cm, apparent complete tumour resection, without clinically apparent lymph node or distant metastasis at diagnosis and nonaggressive histologic variant. Results Based on the finding of MEE, 175 (18.0%) patients were upstaged to T3. They were older (53.9 versus 50.6 years; P = 0.004) and were more prone to have multifocal tumours (38.2% versus 24.8%; P = 0.001). Radioiodine ablation therapy (RAI) was administered more often to MEE patients (92% versus 40.5%; P < 0.001), as well as prophylactic lymph node resection (35.4% versus 28.6%, P = 0.048). They were more likely to have biochemical incomplete response (4% versus 0.3%; P = 0.03) at the end of the follow-up period. There was no significant association between MEE and recurrence rate, persistence of disease or disease-specific mortality. Conclusion These results support the changes made to the latest edition of the TNM staging system, regarding MEE. Although incomplete biochemical response is more common in these patients, it does not seem to affect their prognosis.

Invasion in thyroid cancer: Controversies and best practices

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

Predicting the factors associated with central lymph node metastasis in clinical node-negative (cN0) papillary thyroid microcarcinoma

PURPOSE

The aim of the present study was to investigate the risk factors associated with central lymph node metastasis (CLNM) in papillary thyroid microcarcinoma (PTMC).

METHODS

A total of 553 patients with PTMC confirmed by histological examination, who underwent thyroidectomy and central neck dissection (CND), were enrolled. The clinicopathological and ultrasonographic features from the patients were analyzed retrospectively.

RESULTS

PTMC patient age, Hashimoto thyroiditis (HT), tumor location, extrathyroidal extension (ETE), microcalcification and higher E values were correlated with the incidence of CLNM. Multivariate logistic regression analysis showed that age, HT, tumor location, ETE and E_max were related to the extent of CLNM. Chi-squared automatic interaction detection (CHAID) classification tree model showed that patients with tumor in upper/lower third combined ETE had a high risk of CLNM. Furthermore, cN0 PTMC patients with age ≤ 45 years and ETE had more extensive CLNM.

CONCLUSION

Our observations could be helpful for the assessment of prognostic factors of PTMC patients with CLNM.

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.

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

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

Minimal extrathyroidal extension affects the prognosis of differentiated thyroid cancer: Is there a need for change in the AJCC classification system?

Minimal extrathyroidal extension (ETE) is defined as tumor cells extending to the sternothyroid muscle or perithyroidal soft tissue. However, there is controversy regarding whether the magnitude of ETE (minimal or gross) should be considered in assigning a precise TNM stage to patients with thyroid cancer in the seventh/eighth editions of the AJCC system. The present study evaluated Surveillance, Epidemiology, and End Results data from 107,114 patients with differentiated thyroid cancer (2004–2013) to determine whether the magnitude of ETE (thyroid confinement, minimal, or gross) influenced the ability to predict cancer-specific survival (CSS) and overall survival (OS). Patient mortality was evaluated using Cox proportional hazards regression analyses and Kaplan-Meier analyses with log-rank tests. The cancer-specific mortality rates per 1,000 person-years were 1.407 for the thyroid confinement group (95% CI: 1.288–1.536), 5.133 for the minimal ETE group (95% CI: 4.301–6.124), and 29.735 for the gross ETE group (95% CI: 28.147–31.412). Relative to the thyroid confinement group, patients with minimal ETE and gross ETE had significantly poorer CSS and OS in the univariate and multivariate analyses (both P<0.001). After propensity-score matching according to age, sex, and race, we found that thyroid confinement was associated with better CSS and OS rates than minimal ETE (P<0.001) and gross ETE (P<0.001). These results from a population-based cohort provide a reference for precise personalized treatment and management of patients with minimal ETE. Furthermore, it may be prudent to revisit the magnitude of ETE as advocated by the AJCC and currently used for treatment recommendation by the American Thyroid Association.

Survival in Differentiated Thyroid Cancer: Comparing the AJCC Cancer Staging Seventh and Eighth Editions

BACKGROUND

The American Joint Committee on Cancer Cancer Staging System for differentiated thyroid cancer has been recently revised. The purpose of this study was to compare survival prognostication between the seventh and eighth editions.

MATERIALS AND METHODS

We retrospectively reviewed 2579 differentiated thyroid cancer patients who underwent surgery at MD Anderson Cancer Center between 2000 and 2015. Disease-specific survival (DSS) and overall survival were estimated using the Kaplan-Meier method and compared using log rank test. The effect of potential predictor was estimated using Cox proportional hazards model. Power of survival prediction was estimated using Harrell's C concordance index (C-index), and predictive capacities for DSS were estimated using proportion of variance explained (PVE).

RESULTS

Revision of tumor-node-metastasis (TNM) categories, age cutoff, and stage reassignment in the 8^th edition caused reclassification of overall stage compared with the seventh edition. The proportion of patients in stage I and II increased from 62% to 83% and 5% to 12%, respectively, while the proportion of patients in stage III and IV decreased from 20% to 2% and 14% to 3%, respectively. Ten-year DSS for stages I-IV based on the seventh edition were 100%, 97.5%, 98.3%, and 82.6%, respectively, while 10-year DSS for the corresponding stage in the eighth edition were 99.8%, 88.3%, 72.4%, and 71.9%, respectively. In multivariate analysis for both seventh edition (C-index 0.94, PVE 4.6%) and eighth edition (C-index 0.94, PVE 4.8%), the factors predictive of worse outcome for DSS were older age, advanced tumor size category, and distant metastasis while cervical lymph node metastases did not predict worse survival. For the eighth edition, patients <55 years of age with stage II disease had significantly worse DSS (p < 0.001) than patients ≥55 years with stage II disease but appeared to be similar to patients ≥55 years with stage III (p = 0.742) and IV disease (p = 0.566). Patients ≥55 years old with T3a and T3b disease had 10-year DSS of 67% and 92%, respectively (p = 0.390).

CONCLUSION

The AJCC eighth edition is similar to the seventh edition in disease-specific survival prediction. Potential modifications that may improve disease-specific survival prediction in future renditions include reconsideration of T3b tumor category and upstaging classification of patients <55 years of age with distant metastases.

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.

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

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

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

INTRODUCTION

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

The New TNM Staging System for Thyroid Cancer and the Risk of Disease Downstaging

In October 2016 the American Joint Committee on Cancer (AJCC) published the 8th edition of the AJCC/TNM cancer staging system and it has been introduced in clinical practice since 1st January 2018. The effect of most of the changes in the new edition was the downstaging of a significant number of patients into lower stages, reflecting their low risk of thyroid cancer-related death. One of the most relevant modification refers to the role of the microscopic extra-thyroidal tumor invasion, which is no longer considered as criterion for the classification of T3 tumors. With the present study we want to assess the impact of the changes of the new staging system and therefore we analyzed or casistic of 84 T1-T3 thyroid-cancer patients. The results of our analysis show that he downstaging of patients according to the 8th TNM edition does not necessarily reflect less aggressive disease: we actually reported 2 lymph-nodal recurrences (40%) in the five patients that were downstaged from pT3 to pT2 and the lypmh-nodal recurrence rate for stage I rises from 0% with the 7th TNM edition to 5.3% with the 8th edition.

Metastatic lymph node characteristics as predictors of recurrence/persistence in the neck and distant metastases in differentiated thyroid cancer

OBJECTIVE

The aim of this study was to evaluate the association between this characteristic and outcomes in patients with lymph node metastasis in a Brazilian cohort.

SUBJECTS AND METHODS

This study examined a retrospective cohort of adult patients diagnosed with differentiated thyroid cancer and lymph node metastases from 1998 to 2015 in two referral centers. Number, location, size and extranodal extension (ENE) of metastatic lymph nodes were assessed and correlated with response to initial therapy.

RESULTS

A greater number of metastatic nodes, larger size, presence of lateral neck disease and ENE were all associated with a lower probability of achieving an excellent response to initial therapy (p ≤ 0.05 for all these parameters). Local recurrent disease had a significant association with lymph node number (6 in the recurrence/persistence group versus 4 in the non-recurrent group; p = 0.02) and ENE (19.2 versus 75%, p = 0.03). Lateral neck disease was the only characteristic associated with distant metastasis and was present in 52.1% of the group without metastasis and 70.4% of the group with metastasis (p = 0.001).

CONCLUSION

The lymph node characteristics were associated with response to initial therapy and neck recurrence/persistence, confirming the importance of the analysis of these factors in risk stratification in a Brazilian population and its possible use to tailor initial staging and long term follow-up.

Comparison of the Seventh and Eighth Editions of the American Joint Committee on Cancer/Union for International Cancer Control Tumor-Node-Metastasis Staging System for Differentiated Thyroid Cancer

OBJECTIVE

To evaluate the efficacy and prognostic validity for disease-specific survival (DSS) of the eighth edition American Joint Committee on Cancer/Union for International Cancer Control tumor-node-metastasis (TNM) staging system (TNM-8) compared to the seventh edition (TNM-7) in patients with differentiated thyroid carcinoma (DTC).

METHODS

The seventh and eighth editions of the TNM staging system were applied to 1613 DTC patients who underwent thyroid surgery between 1996 and 2003. The proportion of variation explained and Harrell's c-index were evaluated to compare the predictive capability of DSS.

RESULTS

The mean age of the patients was 44.7 years, and the median follow-up period was 11.2 years. When TNM-8 was applied, 63% of T3 and 3% of N1b DTCs were downgraded to T1/T2 and N1a, respectively. About 38% of patients were downstaged according to TNM-8. The 10-year DSS rates in TNM-7 stages I, II, III, and IV were 99.7%, 98.2%, 98.8%, and 83.2%, respectively. Those in TNM-8 stages I, II, III, and IV were 99.6%, 95.4%, 72.3%, and 48.6%, respectively. The proportion of variation explained values of TNM-7 and TNM-8 were 6.0% and 7.0%, respectively. The Harrell's c-index of TNM-7 was 0.86 and that of TNM-8 was 0.88.

CONCLUSIONS

A significant number of patients were reclassified to lower stages with the application of TNM-8 compared to TNM-7. Applying TNM-8 could improve the accuracy of the staging system for predicting DSS in patients with DTC.

Prognostic markers in well differentiated papillary and follicular thyroid cancer (WDTC)

OBJECTIVES

WDTC (papillary and follicular thyroid cancer) make up around 90% of all thyroid tumours. Overall, the prognosis in patients with WDTC is excellent. However, there are small cohorts of patients who experience a more aggressive form of disease which is often associated with certain poor prognostic factors. Identifying these patients at an early stage is imperative for guiding treatment decisions. With recent developments in this area we plan to discuss the current evidence surrounding prognostic markers.

METHODS

The literature regarding prognostic factors in WDTC was reviewed using an electronic database Medline - Pubmed. Using the MeSH search engine specific prognostic factors including age, size, grade, lymph node involvement, distant metastasis, extension/invasion, ethnic background, radioactive iodine avidity, and thyroglobulin level and their association with WDTC were evaluated. A broader search of prognostic markers in thyroid cancer was also carried out to avoid missing other pertinent markers.

RESULTS

Multiple clinical and pathologic variables have been shown to be poor prognostic factors in WDTC with statistical significance. Extensive extrathyroidal extension and age may be the most important factors when predicting clinical outcomes in WDTC, although the age threshold may be increased from 45 to 55 years in due course.

CONCLUSIONS

Management of WDTC has changed considerably over the last two years as reflected in evolving British and American Thyroid Guidelines. In all cases a combined multi-disciplinary approach, with consideration of the available guidelines and stratification systems should be utilised when planning an individualised treatment program to offer the best contemporary care to WDTC patients.

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

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

Minimal extrathyroidal extension does not affect survival of well-differentiated thyroid cancer

Differentiated thyroid cancer (DTC) with minimal extrathyroidal extension (MEE) is classified as stage III regardless of the tumor size. In this study, we aim to examine the effect of MEE on the overall survival and management of this population. A retrospective cohort study was performed, which utilized the National Cancer Database (NCDB), 2004-2012. The study population included patients, aged ≥ 45 years, who underwent surgery for DTC (pT3N0M0) with MEE compared to that in patients with pT2N0M0. A total of 9556 patients were included. These were divided into four groups, 4410 patients with pT2N0M0 (Group 1: T ≤ 4 cm without MEE), 3274 with pT3N0M0 (Group 2: T ≤ 4 cm with MEE), 447 with pT3N0M0 (Group 3: T > 4 cm with MEE) and 1430 patients with pT3N0M0 without MEE (Group 4: T > 4 cm without MEE). Median follow-up time was 46.7 months (interquartile range: 27.8-72.1). Patients in Group 2 (T ≤ 4 cm with MEE) had no significant worse survival compared to patients in Group 1 (T ≤ 4 cm without MEE) (P = 0.85), whereas Groups 3 and 4 (T > 4 cm), both had significantly lower survival (P < 0.001) with no difference between the two groups. Total thyroidectomy was associated with improved overall survival compared to that in lobectomy in Group 4 (T > 4 cm without MEE). Radioiodine utilization was associated with improved survival only with tumors larger than 4 cm with or without MEE. In DTC patients aged older than 45 years of age with tumor size less than 4 cm, MEE has no survival significance. Tumor size is an independent prognostic marker regardless of MEE status. Our data support re-evaluation of the current staging system.

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.

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

BACKGROUND

Extrathyroidal extension (ETE) is a significant prognostic factor in papillary thyroid carcinoma (PTC). Minimal extrathyroidal extension (mETE) is characterized by involvement of the sternothyroid muscle or perithyroid soft tissue, and is generally identified by light microscope examination. Patients with mETE, identified pathologically, are automatically upstaged to pT3. However, the prognostic implications of mETE have been a source of controversy in the literature. Moreover, there is also controversy surrounding the identification of mETE on pathological specimens. The objective of this study was to determine the level of agreement among expert pathologists in the identification of mETE in PTC cases.

METHODS

Eleven expert pathologists from the United States, Italy, and Canada were asked to perform a review of 69 scanned slides of representative permanent sections of PTC specimens. Each slide was evaluated for the presence of mETE. The pathologists were also asked to list the criteria they use to identify mETE.

RESULTS

The overall strength of agreement for identifying mETE was slight (κ = 0.14). Inter-pathologist agreement was best for perithyroidal skeletal muscle involvement (κ = 0.46, moderate agreement) and worst for invasion around thick-walled vascular structures (κ = 0.02, slight agreement). In addition, there was disagreement over the constellation of histologic features that are diagnostic for mETE, which affected overall agreement for diagnosing mETE.

CONCLUSIONS

Overall agreement for the identification of mETE is poor. Disagreement is a result of both variation in individual pathologists' interpretations of specimens and disagreement on the histologic criteria for mETE. Thus, the utility of mETE in staging and treatment of PTC is brought into question. The lack of concordance may explain the apparent lack of agreement regarding the prognostic significance of this pathologic feature.

Implementing the Modified 2009 American Thyroid Association Risk Stratification System in Thyroid Cancer Patients with Low and Intermediate Risk of Recurrence

OBJECTIVE

The primary purpose of this study was to validate the proposed modified 2009 American Thyroid Association Risk Stratification System (M-2009-RSS) in patients with thyroid cancer and to compare the findings with those of the 2009 ATA Risk of Recurrence (2009 ATA-RR) and the Ongoing Risk of recurrence system. The secondary purpose was to assess which risk stratification system had the best predictive value to foresee the probability of structural incomplete response or the no evidence of disease (NED) status at the end of follow-up.

SUBJECTS AND METHODS

This retrospective review included 149 patients with differentiated thyroid cancer who had low and intermediate 2009 ATA-RR and were treated at a single experienced center and followed-up for a median of 6 years (range 3-12 years). Each patient was risk stratified using both the 2009 ATA-RR and the M-2009-RSS. The primary endpoints were 1) the best response to initial therapy defined as either excellent response, biochemical or structural incomplete response, or indeterminate response; 2) clinical status at final follow-up defined as either NED, biochemical incomplete response, structural incomplete response, indeterminate response, or recurrence (biochemical or structural disease identified after a period of NED), and 3) ongoing RR defined as low or high risk according several outcomes after initial treatment.

RESULTS

Mean age of included patients was 45.3±13 years. Both the ATA 2009-RR and the M-2009-RSS provided clinically meaningful graded estimates with regard to the status of NED at the end of follow-up in low-risk patients (84% for 2009 ATA-RR and 74% for M-2009-RSS) or the likelihood of having persistent structural disease (0% for 2009 ATA RR and 3.6% for the M-2009-RSS). When patients were classified as low risk, the positive predictive value (PPV) and negative predictive value (NPV) to predict structural disease was 0% and 88.7% for the 2009 ATA-RR, 3.6% and 86.5% for the M-2009-RSS, and 1.6% and 68.2% for the ongoing RR (p=0.022 and 0.055 of chi-square test for PPV and NPV, respectively).

CONCLUSIONS

Despite expanding the definition of low risk to include small-volume lymph node metastases, minor extrathyroidal extension, and minimally invasive follicular thyroid cancer, the M-2009-RSS predicts clinical outcomes (structural incomplete response and NED at the end of follow-up) that are very similar to the previously validated 2009 ATA RR classification system.

Clinicopathological Significance of Minimal Extrathyroid Extension in Solitary Papillary Thyroid Carcinomas

Background

The definitive diagnosis of minimal extrathyroid extension (ETE) is subjective because a well-defined true capsule is absent in the thyroid gland. We subclassified the extent of minimal ETE and investigated the clinicopathological significance of the presence of minimal ETE in patients with solitary papillary thyroid carcinomas (PTCs) and solitary papillary thyroid microcarcinomas (PTMCs).

Methods

A series of 546 patients with solitary PTCs, including 144 patients with solitary PTMCs, were retrospectively analyzed. Whether the presence of minimal ETE had an effect on recurrence-free survival (RFS) along with other clinicopathological parameters was investigated.

Results

The only independent prognostic factor found to be associated with recurrence was the presence of LN metastasis in solitary PTC (p = 0.002) but not in solitary PTMC groups (p = 0.073). The presence of minimal ETE had no effect on RFS in both solitary PTC (p = 0.053) and solitary PTMC (p = 0.816).

Conclusions

The presence of minimal ETE has no significant influence on RFS in solitary PTC and PTMC. There is a risk of overrepresenting the T3 category in solitary PTC and PTMC patients with minimal ETE.

Electronic supplementary material

The online version of this article (doi:10.1245/s10434-015-4659-0) contains supplementary material, which is available to authorized users.

Recombinant human thyroid-stimulating hormone-aided remnant ablation achieves a response to treatment comparable to that with thyroid hormone withdrawal in patients with clinically relevant lymph node metastases

It has already been shown that remnant ablation in patients with thyroid cancer and lymph node (LN) metastases has similar results when patients are prepared after recombinant human thyroid-stimulating hormone (rhTSH) therapy or thyroid hormone withdrawal (THW). Due to the current changes in the risk-of-recurrence classifications, we decided to evaluate the initial response to treatment and the outcome at medium-term follow-up in 40 consecutive patients with clinically relevant lymph nodes who received radioiodine remnant ablation after rhTSH therapy (n = 20) or THW (n = 20). Each patient received either 100 or 150 mCi 131-I for ablation based on TNM status, and the mean amounts of 131-I used in the 2 groups were not significantly different. An excellent response to treatment was observed in 45% of the patients prepared after rhTSH therapy compared to 20% of those prepared after THW (p = 0.08). Three patients (2 in the THW group and 1 in the rhTSH group) who had N1a in the initial surgery presented with structural persistence as an initial response to treatment. One patient in the THW group had a follow-up of the persistent disease with no surgical treatment, and 2 others received a lateral LN dissection. When the status at final follow-up was considered (median follow-up 3.3 years, range 3-4.2), 60% of the patients ablated after rhTSH therapy were considered with no evidence of disease, compared to 30% of those who underwent THW. The frequency of structural persistence (metastatic LN) was similar in the 2 groups (15 vs. 25%), and the distribution of the responses at final follow-up was not statistically significantly different (p = 0.12). We conclude that preparation after rhTSH therapy seems to be as effective as after THW for patients with clinically relevant LN metastases.

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.

Extrathyroidal extension predicts extranodal extension in patients with positive lymph nodes: an important association that may affect clinical management

BACKGROUND

While there is consensus that significant extrathyroidal extension (ETE) (T4) should upstage a patient with well-differentiated thyroid cancer, the importance of minimal ETE (T3) remains controversial. Additionally, the importance of nodal metastases on prognosis has come under scrutiny. Recent publications highlight the importance of size, number of positive nodes, and, in particular, the presence of extranodal extension (ENE) as measures of disease aggressiveness. In this study, we examined whether ETE is a predictor of ENE.

METHODS

A retrospective review was conducted from January 2004 to March 2013. All node-positive patients who underwent total or completion thyroidectomy were included. Histologic features defined by the College of American Pathologists (CAP) protocol for thyroid carcinoma were recorded.

RESULTS

A total of 193 patients qualified for review. Patients who were found to have ETE were 12 times more likely to have lymph nodes in the primary setting with ENE than patients with intrathyroidal primary tumors (p<0.000). After exclusion of all T4 cases (n=6), patients with minimal ETE were 13 times more likely to have ENE than those with no ETE (p<0.000). Twenty percent of microcarcinomas with ETE demonstrated ENE.

CONCLUSION

We have found that the biology of the primary tumor is conferred to the lymph node in that the presence of ETE leads to a significantly higher incidence of ENE. Awareness of this relationship should be accounted for in the management of primary and recurrent lymph nodes. This study shows that minimal ETE is a significant predictor of ENE. Although long-term survival and recurrence follow-up is not available for the majority of patients in this series, the presence of ENE as a surrogate for more aggressive disease biology and its strong association with minimal ETE supports the upstaging of patients with minimal ETE.

Prognostic values of clinical lymph node metastasis and macroscopic extrathyroid extension in papillary thyroid carcinoma

In papillary thyroid carcinoma (PTC), macroscopic extrathyroid extension (Ex) and clinical node metastasis (N) are prominent prognostic factors. Ex is divided into two grades in the UICC TNM classification: minimal and massive Ex. Massive Ex significantly affects patients' prognoses, whereas minimal Ex has little prognostic value. N is also divided into two grades in the TNM classification: N1a and N1b, depending on the location of metastasis, with N1b graded higher than N1a. However, massive Ex and/or N-positive PTC includes patients with a wide range of biological characteristics and prognoses, depending on their degrees of Ex and N. Other clinicopathological features such as age, gender, and tumor size also influence the prognosis. In evaluations of the biological characteristics of PTC patients with Ex and/or N, we should consider the degrees and relationships of Ex and N with other clinicopathological features.

Radioactive iodine treatment for node negative papillary thyroid cancer with capsular invasion only: Results of a large retrospective study

AIM

With thyroid carcinoma the decision to use radioactive iodine (RAI) ablation depends on the risk of poor outcomes. Although extrathyroid extension (ETE) is well known as a risk of poor outcomes for papillary thyroid carcinoma (PTC), the definition of minimal ETE is too broad, as it encompasses both microscopic invasion of the thyroid capsule (capsular invasion [CI]) and macroscopic invasion of the sternothyroid muscle.

METHODS

We conducted a retrospective study to analyze the prognostic benefit of RAI ablation according to the presence of CI in a consecutive series of patients with PTC between October 1997 and December 2008. We studied two groups of patients, including those who received RAI (group I, n = 121) and those who did not (group II, n = 108). During follow-up, we assessed the locoregional recurrence of all patients.

RESULTS

There were no statistically significant difference between the groups regarding locoregional recurrence at follow-up (13.2% for group I vs 9.3% for group II, P = 0.441). The association between RAI and locoregional recurrence in PTC patients with CI remained insignificant after adjusting for potential confounders, such as age, tumor size, sex, lymphatic invasion, vascular invasion and tumor multiplicity (P = 0.409, hazard ratio = 0.698, 95% confidence interval, 0.298-1.639).

CONCLUSIONS

This retrospective study suggests that RAI treatment is not associated with less locoregional recurrence in PTC patients who only demonstrate CI, although further prospective studies are required to confirm these findings.

Pitfalls in the staging of cancer of thyroid

Thyroid cancer includes several neoplasms originating from the thyroid gland-from indolent and curable histologies of differentiated thyroid carcinoma to aggressive anaplastic thyroid carcinoma. Differentiation of thyroid nodules is problematic on CT and MR imaging unless there is evidence of extrathyroidal extension. Evaluation of regional lymph nodes is often performed clinically or with ultrasound. The retropharyngeal and mediastinal lymph nodes are better evaluated by CT and MR imaging. Nuclear scintigraphy is useful for staging and treatment of distant metastasis in differentiated thyroid carcinoma. PET may have a role in aggressive cancers. Accurate staging affects surgical management and subsequent therapy.

Association between the expression of four upregulated miRNAs and extrathyroidal invasion in papillary thyroid carcinoma

Background

MicroRNAs (miRNAs) are important diagnostic and prognostic markers in cancer. In the study reported here, we analyzed the potential relationship between miRNA expression and extrathyroidal invasion in papillary thyroid carcinoma (PTC).

Methods

Samples from 91 patients with PTC were collected from January 2008 to April 2012 at our hospital. To detect the levels of miRNA expression in fresh frozen tissues from patients with extrathyroidal invasion (n = 3) and non-extrathyroidal invasion (n = 3), miRNA array was carried out. The upregulated miRNAs between the two groups were confirmed by using real-time reverse transcriptase polymerase chain reaction.

Results

The levels of miR-146b, miR-221, miR-222, and miR-135b were significantly higher in the extrathyroidal invasion group than in the non-extrathyroidal invasion group (P = 0.001, 0.019, 0.004, and 0.006, respectively). In addition, the miR-146b expression level was significantly higher in the massive extrathyroidal invasion group than in the minimal extrathyroidal invasion group (P = 0.016). The expression levels of miR-146b, miR-222, and miR-135b were significantly associated with tumor size (P = 0.018, 0.008, and 0.024, respectively). The upregulation of miR-146b and miR-222 was significantly associated with higher tumor-node-metastasis stage (P = 0.004 and 0.0001, respectively). The expression level of miR-222 was also correlated with age and sex (P = 0.048 and 0.002, respectively).

Conclusion

Our results reveal that the expression of four miRNAs correlated with extrathyroidal invasion and other clinicopathologic features in PTCs, which may support their potential clinical value as prognostic biomarkers for PTCs.

German Association of Endocrine Surgeons practice guideline for the surgical management of malignant thyroid tumors

INTRODUCTION

Over the past years, the incidence of thyroid cancer has surged not only in Germany but also in other countries of the Western hemisphere. This surge was first and foremost due to an increase of prognostically favorable ("low risk") papillary thyroid microcarcinomas, for which limited surgical procedures are often sufficient without loss of oncological benefit. These developments called for an update of the previous practice guideline to detail the surgical treatment options that are available for the various disease entities and tumor stages.

METHODS

The present German Association of Endocrine Surgeons practice guideline was developed on the basis of clinical evidence considering current national and international treatment recommendations through a formal expert consensus process in collaboration with the German Societies of General and Visceral Surgery, Endocrinology, Nuclear Medicine, Pathology, Radiooncology, Oncological Hematology, and a German thyroid cancer patient support organization.

RESULTS

The practice guideline for the surgical management of malignant thyroid tumors includes recommendations regarding preoperative workup; classification of locoregional nodes and terminology of surgical procedures; frequency, clinical, and histopathological features of occult and clinically apparent papillary, follicular, poorly differentiated, undifferentiated, and sporadic and hereditary medullary thyroid cancers, thyroid lymphoma and thyroid metastases from primaries outside the thyroid gland; extent of thyroidectomy; extent of lymph node dissection; aerodigestive tract resection; postoperative follow-up and surgery for recurrence and distant metastases.

CONCLUSION

These evidence-based recommendations for surgical therapy reflect various "treatment corridors" that are best discussed within multidisciplinary teams and the patient considering tumor type, stage, progression, and inherent surgical risk.

The definition of minimal extrathyroid extension in thyroid pathology by analyzing sizable intra- and extrathyroid blood vessels

Background

To define the exact boundary of the intrathyroid and extrathyroid aspects of a gland when determining the extent of cancer invasion, we plan to clarify the definition of sizable vascular structures, which is one of the helpful histologic clues in determining a minimal extrathyroid extension. We hypothesized that arterial wall thicknesses in extrathyroid soft tissue would be significantly different from the arteries in the thyroid parenchyma.

Methods

Twenty cases of papillary carcinoma were selected. The numbers and wall thicknesses of the arteries and arterioles in intrathyroid and extrathyroid tissue were evaluated. The absence of nerve tissue in the thyroid gland was confirmed using the S-100 protein immunohistochemical stain.

Results

The comparison of the mean thicknesses of the total arteries between the extrathyroid and intrathyroid tissues in the retrospective study (26.88 µm vs. 15.07 µm, respectively) and the prospective study (35.24 µm vs. 16.52 µm, respectively) revealed significant differences (p=0.000). The greatest thickness of the intrathyroid arteries was 67.93 µm.

Conclusions

According to our results, the study showed that the extrathyroidal arteries were significantly thicker than the intrathyroidal arteries. We suggest that the sizable blood vessels of extrathyroidal arteries should be greater than 67.93 µm in thickness.