Differentiated and Medullary Thyroid Cancer: Surgical Management of Cervical Lymph Nodes

Prediction of cervical lymph node metastasis in differentiated thyroid cancer based on radiomics models

OBJECTIVE

The accurate clinical diagnosis of cervical lymph node metastasis plays an important role in the treatment of differentiated thyroid cancer (DTC). This study aimed to explore and summarize a more objective approach to detect cervical malignant lymph node metastasis of DTC via radiomics models.

METHODS

PubMed, Web of Science, MEDLINE, EMBASE, and Cochrane databases were searched for all eligible studies. Articles using radiomics models based on ultrasound, computed tomography, or magnetic resonance imaging to assess cervical lymph node metastasis preoperatively were included. Characteristics and diagnostic accuracy measures were extracted. Bias and applicability judgments were evaluated by the revised QUADAS-2 tool. The estimates were pooled using a random-effects model. Additionally, the leave-one-out method was conducted to assess the heterogeneity.

RESULTS

Twenty-nine radiomics studies with 6160 validation set patients were included in the qualitative analysis, and 11 studies with 3863 validation set patients were included in the meta-analysis. Four of them had an external independent validation set. The studies were heterogeneous, and a significant risk of bias was found in 29 studies. Meta-analysis showed that the pooled sensitivity and specificity for preoperative prediction of lymph node metastasis via US-based radiomics were 0.81 (95% CI, 0.73-0.86) and 0.87 (95% CI, 0.83-0.91), respectively.

CONCLUSIONS

Although radiomics-based models for cervical lymphatic metastasis in DTC have been demonstrated to have moderate diagnostic capabilities, broader data, standardized radiomics features, robust feature selection, and model exploitation are still needed in the future.

ADVANCES IN KNOWLEDGE

The radiomics models showed great potential in detecting malignant lymph nodes in thyroid cancer.

Thyroglobulin Antibody (TgAb) Positive is an Independent Risk Factor for Lymph Node Metastasis in Patients with Differentiated Thyroid Carcinoma

Objective

To investigate the relationship between lymph node metastasis and the clinicopathologic features of differentiated thyroid carcinoma (DTC) patients with thyroglobulin antibody (TgAb) positive and negative.

Methods

A total of 443 patients with DTC were included in this study. Clinicopathological data of the patients were collected, including tumor size, clinical stage, calcification, Hashimoto's thyroiditis, extra-membrane infiltration, BRAF V600E mutation status, and thyroid-related hormone and antibody levels. The relationship between of lymph node metastasis and clinicopathologic features was analyzed.

Results

There were 227(51.2%) TgAb negative and 216(48.8%) TgAb positive DTC patients. Compared with patients without lymph node metastasis, DTC patients with lymph node metastasis had a higher proportion of patients with <55 years of age, maximum tumor diameter >1cm, calcification, BRAF V600E mutation, and TgAb positive. Multivariate regression logistic analysis showed that <55 years old (odds ratio (OR): 2.744, 95% CI: 1.665-4.522, P<0.001), maximum tumor diameter >1cm (OR: 2.163, 95% CI: 1.431-3.271, P<0.001), BRAF V600E mutation (OR: 2.489, 95% CI: 1.397-4.434, P=0.002), and TgAb positive (OR: 1.540, 95% CI: 1.020-2.326, P=0.040) were risk factors for lymph node metastasis. Maximum tumor diameter >1cm and BRAF V600E increased the risk by more than one fold for lymph node metastasis in TgAb-negative and TgAb-positive DTC patients.

Conclusion

Younger age (<55 years old), maximum tumor diameter >1cm, BRAF V600E mutation, and TgAb positive were independent risk factors for lymph node metastasis in DTC. And maximum tumor diameter >1cm and BRAF V600E mutation were risk factors for lymph node metastasis both in TgAb positive and negative DTC patients.

Early postoperative prediction of the risk of distant metastases in medullary thyroid cancer

Purpose

The purpose of this study was to develop and validate a nomogram for estimating the risk of distant metastases (DM) in the early postoperative phase of medullary thyroid cancer (MTC).

Patients and methods

We retrospectively reviewed cases of patients diagnosed with MTC from the Surveillance, Epidemiology, and End Results (SEER) database from 2007 to 2017. In addition, we gathered data on patients who diagnosed as MTC at Department of Thyroid Surgery in the First Hospital of Jilin University between 2009 and 2021. Four machine learning algorithms were used for modeling, including random forest classifier (RFC), gradient boosting decision tree (GBDT), logistic regression (LR), and support vector machine (SVM). The optimal model was selected based on accuracy, recall, specificity, receiver operating characteristic curve (ROC), and area under curve (AUC). After that, the Hosmer-Lemeshow goodness-of-fit test, the brier score (BS) and calibration curve were used for validation of the best model, which allowed us to measure the discrepancy between the projected value and the actual value.

Results

Through feature selection, we finally clarified that the following four features are associated with distant metastases of MTC, which are age, surgery, primary tumor (T) and nodes (N). The AUC values of the four models in the internal test set were as follows: random forest: 0.8786 (95% CI, 0.8070-0.9503), GBDT: 0.8402 (95% CI, 0.7606-0.9199), logistic regression: 0.8670(95%CI,0.7927-0.9413), and SVM: 0.8673 (95% CI, 0.7931-0.9415). As can be shown, there was no statistically significant difference in their AUC values. The highest AUC value of the four models were chosen as the best model since. The model was evaluated on the internal test set, and the accuracy was 0.84, recall was 0.76, and specificity was 0.87. The ROC curve was drawn, and the AUC was 0.8786 (95% CI, 0.8070-0.9503), which was higher than the other three models. The model was visualized using the nomogram and its net benefit was shown in both the Decision Curve Analysis (DCA) and Clinical Impact Curve (CIC).

Conclusion

Proposed model had good discrimination ability and could preliminarily screen high-risk patients for DM in the early postoperative period.

Management of lymph nodes in medullary thyroid carcinoma: A review

Introduction

Medullary Thyroid Carcinoma (MTC) as a neuroendocrine tumor that arises from the parafollicular C-cells and shows a potentially aggressive behavior with early lymph node metastasis. MTC cells do not absorb radioactive iodine and are not sensitive to Thyroid Stimulating Hormone (TSH) suppression, and therefore surgery is the most effective option for curative therapy.

Results

Medical imaging and biomarkers (calcitonin & CEA) assessment are necessary to determine the appropriate approach to lymph nodes surgery in MTC. Prophylactic central, lateral or contralateral neck dissections are recommended based on calcitonin level and volume of tumor. In general, guidelines are in agreement with prophylactic central dissection in most cases. Central and lateral dissections are recommended in all guidelines and review articles if lymphadenopathy is confirmed in preoperative examinations. Because lymph node dissection in most cases of locally advanced or metastatic MTC has no prognostic effect, dissection is done with palliative goal with maximum attention to maintaining function in these cases. In patients with an incomplete lymph node dissection, decision for reoperation can be based on calcitonin levels and the number of metastatic lymph nodes removed in previous surgery. Symptoms as well as speed of disease progression are also important in adopting the type of surgery. Consensus is in favor of reoperation in patients with recurrent regional MTC without distant metastasis.

Conclusion

Thyroidectomy is mandatory in patients with MTC but the type and extension of lymph node dissection are depending on the calcitonin level and tumor burden.

•

Surgery is the most effective treatment option for MTC.

•

Prophylactic central, lateral or contralateral neck dissections are recommended based on calcitonin level.

•

Therapeutic central and lateral dissection is recommended if lymphadenopathy is confirmed.

•

In locally advanced or metastatic MTC dissection is done with maximum attention to maintaining function.

Role and Extent of Neck Dissection for Neck Lymph Node Metastases in Differentiated Thyroid Cancers

Differentiated thyroid cancers (DTC) consist of 95% of thyroid tumors and include papillary thyroid cancer (PTC), follicular thyroid cancer (FTC), and Hurthle cell thyroid cancer (HTC). Rates of lymph node metastases are different depending on histologic subtypes and <5% in FTC and between 5% and 13% in HTC. Lymph node metastasis is more frequent in PTC and while rate of clinical metastasis can be seen approximately 30% rate of routine micrometastasis can be seen up to 80%. Lymph node metastasis of DTC mostly develops first in the Level VI lymph nodes at the central compartment starting from the ipsilateral paratracheal lymph nodes and then spreading to the contralateral paratracheal lymph nodes. Spread to the Level VII is mostly after Level VI invasion. Subsequent spread is to the lateral neck compartments of Levels IV, III, IIA, and VB and sometimes to the Levels IIB and VA. Occasionally skip metastasis to the lateral neck compartments develop without spreading to the central compartments and this situation is more frequent in upper pole tumors. Although application of prophylactic central neck dissection (pCND) in DTC increases the rate of complication, due to its unclear effects on oncologic results and quality of life, the interest to the pCND is decreasing and debate on its surgical extent is increasing. pCND is not essential in DTC and characteristics of patient and tumor and experience of surgeon should be considered when deciding for pCND. Due to lower complication rate of one sided pCND compared to bilateral central neck dissection (CND), low possibility of contralateral central neck metastasis and low risk of recurrence, application of one-sided CND is logical. Although therapeutic CND (tCND) is the standart treatment when there is a clinically involved lymph node, extent of dissection is a matter of debate. A case-based decision for the extent of tCND can be made by considering patient and tumor characteristics and experience of the surgeon. Due to the higher complication risk of bilateral CND, unilateral tCND can be performed if there is no suspicious lymph node on the contralateral side and bilateral tCND can be applied when there is a suspicion for metastasis only on the contralateral side or there are features for risk of metastasis to the contralateral side. In patients with clinical central metastasis owing to intra-operative pathology results by frozen section procedure are compatible with post-operative pathology results, when there is a suspicion for contralateral metastasis, a decision for one- or two-sided dissection can be made using frozen section procedure. In DTC, it can be stated that there is a consensus in the literature about not performing prophylactic lateral neck dissection (LND), but performing therapeutic LND (tLND). In addition, there is a debate on the extent of tLND. In a meta-analysis about lateral metastasis, the rates of metastasis to the Levels IIA, IIB, III, IV, VA, and VB were 53.1%, 15.5%, 70.5%, 66.3%, 7.9%, and 21.5%, respectively. Ultrasonography (USG) is an effective procedure for detection of cervical nodal metastasis on lateral compartment. Pre-operative imaging with USG and/or combination with the fine needle aspiration biopsy (cytology/molecular test/Thyroglobulin test) can allow pre-operative detection and verification of lateral lymph node metastasis. Extent of tLND can be determined to minimize morbidity considering pre-operative USG findings, pre-operative tumor and clinical features of lateral metastasis. Especially in the presence of limited lateral metastases, limited selective LND such as Levels III, IV or Levels IIA, III, IV can be applied according to the patient. Levels IIB and VB should be added to the dissection in the presence of metastases in these regions. In cases that increase the risk of Level IIB involvement, such as presence of metastasis at Level IIA, extranodal tumor involvement, presence of multifocal tumor, and in cases that increase the risk of Level VB involvement such as macroscopic extranodal spread, and simultaneous metastases at Levels II, III, IV; Levels IIB and VB can be added to dissection material. Levels I and VA should be added to the dissection in the presence of clinically detected metastases.

Surgery and Radioactive Iodine Therapeutic Strategy for Patients Greater Than 60 Years of Age with Differentiated Thyroid Cancer

PURPOSE

The purpose of the current study was to determine whether older patients with differentiated thyroid cancer (DTC) who received surgical treatment had a better cause-specific survival (CSS) than patients who were recommended surgery, but declined, and whether patients who underwent postoperative RAI-131 therapy had an impact on CSS based on TNM staging and number of lymph node metastases for all total or near-total thyroidectomy patients. Patients and Methods: This retrospective, population-based study analyzed the clinical data of 162 DTC patients from signal institution in China and 26,487 cases from the Surveillance, Epidemiology, and End Results (SEER) program registry. The patients were divided into two groups (underwent surgery and surgery recommended, but not performed) in the SEER cohort. Furthermore, patients were grouped as follows: T4; N1b; M1; T1-3N0-1a; specific number of lymph node metastases; and total or near-total thyroidectomy. Results: The 120-month cause-specific survival (CSS) rate of women and men showed a gradual declining trend from 60-64 to ≥80 years of age in the group that underwent surgery. The CSS rate of women and men showed a marked downward and irregular trend with an increase in age in the recommended, but no surgery group in the SEER cohort. Univariate analysis indicated that the surgery group had a higher 120-month CSS in women in most stages and men, compared with the no surgery group in the SEER cohort. The analysis of the SEER cohort showed that RAI-131 therapy was associated with an improved 80-month CSS in T4/N1b/M1 women (P < 0.0183) and men (P < 0.0011). However, there were no CSS differences between the RAI-131 therapy and the no-RAI-131 group for the patients with T4/N1b/M1 (AJCC 7th) thyroid cancer in the Chinese cohort. There was no CSS difference in women or men between the T1-3N0 and T1-3N1a patients in the SEER cohort. And similar findings were observed in T1-3N1a patients in the Chinese cohort. There was no statistical difference between the two subgroups. Conclusions: Surgical treatment should be recommended for elderly DTC patients because surgery can lead to a better CSS. High-risk patients achieve a higher benefit-to-risk ratio with RAI-131 therapy. To avoid the adverse effects associated with RAI-131 therapy, a multidisciplinary discussion should be arranged for intermediate- and low-risk patients.

Medullary thyroid cancer: What is the optimal management of the lateral neck in a node negative patient at index operation?

BACKGROUND

Medullary thyroid cancer is a neuroendocrine malignancy that can occur sporadically or as the result of genomic rearranged during transfection mutations. Medullary thyroid cancer has a higher rate of metastasis than well-differentiated thyroid cancer. Lateral neck dissection is often performed, and its prophylactic use is controversial.

METHODS

Single-center, retrospective review (2000-2017) of patients undergoing primary surgical treatment for medullary thyroid cancer who had negative lateral neck imaging preoperatively. Demographics, genetic associations, clinical, and imaging findings were analyzed. Locoregional recurrence, overall recurrence, and overall survival were examined.

RESULTS

A total of 110 patients were identified, of which 18 underwent prophylactic lateral neck dissection and 92 did not. Age, sex distribution, preoperative calcitonin levels, and follow-up were similar among groups. Overall recurrence was 20% for no prophylactic lateral neck dissection and 39% for prophylactic lateral neck dissection (P = .46). Most recurrences were locoregional recurrence, 7.6% for no prophylactic lateral neck dissection versus 22% for prophylactic lateral neck dissection (P = .08), half of it being to the lateral neck in both groups. A total of 7 patients from the no prophylactic lateral neck dissection group required treatment for recurrences versus 4 patients in prophylactic lateral neck dissection group (P = .57). Overall survival at 5 years was similar, 43% the no prophylactic lateral neck dissection group and 31% for prophylactic lateral neck dissection group (P = .52).

CONCLUSION

Lateral neck dissection has no effect in decreasing locoregional or overall recurrences in medullary thyroid cancer and has no effect in overall survival when performed prophylactically at index surgical intervention.

Total thyroidectomy with therapeutic level II-IV neck dissection for papillary thyroid carcinoma: level VI recurrence patterns

OBJECTIVE

Lateral and central compartments cervical lymph nodes metastases are common among patients with papillary thyroid carcinoma (PTC). Elective level VI neck dissection during thyroidectomy and lateral neck dissection (LND) for the treatment of PTC with lateral compartment lymph node metastases is controversial because of the uncertain benefit in clinical outcomes and increased risks of surgical morbidity. We aimed to determine the potential benefit of elective level VI neck dissection in patients with cN1 papillary thyroid carcinoma (PTC) by investigating the rate and pattern of locoregional recurrence in PTC patients who underwent total thyroidectomy and therapeutic lateral node dissection (LND; levels II-IV) without elective level VI dissection.

METHODS

A retrospective cohort study. Data on demographics, clinical presentation and workup, intraoperative and pathological report, postoperative course, adjuvant therapy, recurrence patterns, and overall survival were retrieved from the medical charts of patients who underwent thyroid surgery in our hospital between January 2006 and December 2017.

RESULTS

A total of 1415 thyroidectomies were performed during the study period, of which 802 (56.67%) were for PTC. Of those PTC patients, 228 (28.42%) also underwent LND (levels II-VI) during the same thyroidectomy procedure. Thirty-four (14.91%) of those 228 patients, underwent total thyroidectomy with therapeutic lateral ND II-IV without elective level VI ND. During the follow-up period, five (14.7%) of the latter cohort were diagnosed with recurrence in central neck (level VI) lymph nodes, and four of them (11.7%) were diagnosed with ipsilateral recurrence at level VI.

CONCLUSION

Our results revealed 11.7% rate of clinically significant recurrent disease in ipsilateral level VI which, in our opinion, does not justify routine prophylactic level VI ND dissection when the ipsilateral lateral neck is operated for metastases.

CALCITONIN REVISITED IN 2020

Calcitonin (CT) is a polypeptidic hormone specifically secreted by the thyroid parafollicular cells (C cells) and tangentially involved in human phosphocalcic and bone metabolism. CT from other species (e.g. salmon) is more potent than human CT and has limited therapeutic applications. The neoplastic proliferation of C cells leads to medullary thyroid carcinoma (MTC) generally characterized by an increase of CT secretion. Serum CT is therefore the ideal marker for MTC and can confirm its presence at an early stage, as well as the follow up of its remission or progression/relapse/survival after surgery. There are, however, controversies such as the necessity of CT screening in patients with thyroid nodules, or particular situations causing false positive or false negative results. Our minireview also deals with an up-to-date of surgical procedures for MTC, as well as with non-surgical therapy.

Upregulation of sphingosine kinase 1 is associated with recurrence and poor prognosis in papillary thyroid carcinoma

Sphingosine kinase 1 (SPHK1), an ATP-dependent protein, has previously been demonstrated to be upregulated in several types of human cancer and to play an important role in tumor development and progression. However, the role of SPHK1 in predicting long-term prognosis in patients with papillary thyroid carcinoma (PTC) remains unclear. The purpose of the present study was to assess the significance of SPHK1 expression and its associations with clinicopathological characteristics and prognostic outcome in patients with PTC. Immunohistochemistry staining was retrospectively performed to investigate the expression levels of SPHK1 in 92 PTC tumors. Statistical analyses revealed that high levels of SPHK1 expression were associated with tumor size, lymph node metastasis and the Tumor-Node-Metastasis stage. The disease-free survival (DFS) time of patients that exhibited high levels of SPHK1 expression was shorter, whereas patients with lower levels of SPHK1 expression survived longer. Furthermore, multivariate analysis suggested that upregulated SPHK1 was an independent prognostic factor for predicting DFS of patients with PTC. The results of the Cell Counting Kit-8 and invasion assays demonstrated that SPHK1 overexpression significantly enhanced the proliferation and invasion of a PTC cell line, consistent with clinical findings. The results from the present study provide evidence that elevated expression levels of SPHK1 may be involved in the development and progression of PTC, indicating that this protein may act as a potential prognostic marker for patients with this disease.

Standards and Definitions in Neck Dissections of Differentiated Thyroid Cancer

Papillary and follicular thyroid carcinomas arising from the follicular epithelial cells and forming differentiated thyroid cancer (DTC) consist of >95% of thyroid cancers. Lymph node metastasis to the neck is common in DTC, especially in papillary thyroid cancer. The removal of only the metastatic lymph nodes (berry picking) does not help to achieve a potential positive contribution to the survival and recurrence of lymph node dissection in the DTC. Thus, systematic dissection of the cervical lymph nodes is needed. Today, according to the widely accepted and commonly used definitions and lymph node staging, the deep lymph nodes of the lateral side of the neck are divided into five regions. Based on the fact that some groups have biologically independent regions, Groups I, II, and V are divided into the A and B subgroups. The central region lymph nodes contain VI and VII region lymph nodes, which consist of the prelaryngeal, pretracheal, and right and left paratracheal lymph node groups. Radical neck dissection (RND) is accepted as the standard basic procedure in defining neck dissections. In this method, in addition to all the regions of the Groups I-V lymph nodes at one side, the ipsilateral spinal accessory nerve, internal jugular vein, and sternocleidomastoid muscle are removed. Sparing of one or more of the routinely removed non-lymphatic structures in the RND is called modified RND (MRND), whereas the preservation of one or more of the routinely removed lymph node groups in the RND is termed as selective neck dissection (SND). In difference, the procedure with an addition of a lymph node and/or non-lymphatic structures to routinely removed neck structures in RND is called extended RND. Generally, involving one or more regions of SND are applied for DTC. The removal of the paratracheal, prelaryngeal, and pretracheal lymph node groups at one side is termed as ipsilateral central dissection, whereas the removal of the bilateral paratracheal lymph node groups, in other words, the excision of four lymph node groups in the central region (Groups VI and VII), is defined as bilateral central dissection. In conclusion, bilateral central neck dissection (CND) is the SND in which the regions of VI and VII are removed. In the DTC, CND is prophylactically and therapeutically applied, whereas lateral neck dissection is performed only therapeutically in the presence of clinical metastasis (N1b) in the lateral neck region. Debates on the extent of SNDs to be made in the central and lateral neck regions are still ongoing. Central dissection should be made at least unilaterally. In the lateral side of the neck, SNDs can be applied in different combinations in which at least one region from Groups I to V is removed. The main variables that determine the extent of SND in the central and lateral regions in DTC are the complication rates, the effect of the procedure, and its effect on prognosis and recurrence.

Histogram Analysis of Diffusion Weighted Imaging at 3T is Useful for Prediction of Lymphatic Metastatic Spread, Proliferative Activity, and Cellularity in Thyroid Cancer

Pre-surgical diffusion weighted imaging (DWI) is increasingly important in the context of thyroid cancer for identification of the optimal treatment strategy. It has exemplarily been shown that DWI at 3T can distinguish undifferentiated from well-differentiated thyroid carcinoma, which has decisive implications for the magnitude of surgery. This study used DWI histogram analysis of whole tumor apparent diffusion coefficient (ADC) maps. The primary aim was to discriminate thyroid carcinomas which had already gained the capacity to metastasize lymphatically from those not yet being able to spread via the lymphatic system. The secondary aim was to reflect prognostically important tumor-biological features like cellularity and proliferative activity with ADC histogram analysis. Fifteen patients with follicular-cell derived thyroid cancer were enrolled. Lymph node status, extent of infiltration of surrounding tissue, and Ki-67 and p53 expression were assessed in these patients. DWI was obtained in a 3T system using b values of 0, 400, and 800 s/mm². Whole tumor ADC volumes were analyzed using a histogram-based approach. Several ADC parameters showed significant correlations with immunohistopathological parameters. Most importantly, ADC histogram skewness and ADC histogram kurtosis were able to differentiate between nodal negative and nodal positive thyroid carcinoma. Conclusions: histogram analysis of whole ADC tumor volumes has the potential to provide valuable information on tumor biology in thyroid carcinoma. However, further studies are warranted.