The extent of lateral lymph node dissection in differentiated thyroid cancer in the N+ neck

A scoping review of endoscopic and robotic techniques for lateral neck dissection in thyroid cancer

Introduction

Lateral neck dissection (LND) in thyroid cancer has traditionally been performed by a transcervical technique with a large collar incision. With the rise of endoscopic, video-assisted, and robotic techniques for thyroidectomy, minimally invasive LND is now being performed more frequently, with better cosmetic outcomes.

Methods

The purpose of this paper is to review the different minimally invasive and remote access techniques for LND in thyroid cancer. A comprehensive literature review was performed using PubMed and Google Scholar search terms "thyroid cancer" and "lateral neck dissection" and "endoscopy OR robot OR endoscopic OR video-assisted".

Results

There are multiple surgical options now available within each subset of endoscopic, video-assisted, and robotic LND. The approach dictates the extent of the LND but almost all techniques access levels II-IV, with variability on levels I and V. This review provides an overview of the indications, contraindications, surgical and oncologic outcomes for each technique.

Discussion

Though data remains limited, endoscopic and robotic techniques for LND are safe, with improved cosmetic results and comparable oncologic and surgical outcomes. Similar to patient selection in minimally invasive thyroidectomy, it is important to consider the extent of the LND and select appropriate surgical candidates.

Risk factors for level V metastasis in patients with N1b papillary thyroid cancer

BACKGROUND

Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer, and its incidence has increased. Lateral lymph node metastasis (LLNM) implies a worse prognosis than central lymph node metastasis, with a higher recurrence rate and decreased disease-free survival. The 2015 American Thyroid Association guidelines recommend compartmental node dissection in patients with LLNM to reduce the risk of recurrence and mortality. The purpose of this study was to identify the risk factors for level V lymph node (LN) metastasis in patients with N1b papillary thyroid cancer (PTC).

METHODS

A total of 110 consecutive patients who underwent total thyroidectomy with lateral neck dissection for PTC between April 2016 and April 2022 were retrospectively enrolled. Based on level V metastasis, 94 patients were divided into two groups, and their clinicopathological characteristics were compared. Univariable analysis were used to assess the factors associated with level V metastasis. Spearman correlation analysis were used to assess the correlation between tumors and LN. The receiver operating characteristic (ROC) curve was used to determine the optimal cutoff value for the number of metastatic LNs at each level for level V metastasis.

RESULTS

The number of metastatic LNs and lymph node ratio (LNR) in level II were significantly associated with level V metastasis (P = 0.011 and 0.001, respectively). The number of metastatic LNs in level II and those in the total number of levels correlated with the number of metastatic LNs in level V (rho = 0.331, 0.325, and P = 0.001, 0.001, respectively). The cutoff value for the number of metastatic LNs in level II was defined as 2.5 (area under the curve = 0.757, sensitivity = 50%, specificity = 82.5%, 95% confidence interval [CI] 0.626-0.889, P = 0.002). Simultaneous 3-level metastasis (level II, III, and IV) and 3-level with ≥ 2.5 metastatic LNs in level II were significantly associated with level V metastasis (P = 0.003 and 0.002).

CONCLUSIONS

The number of metastatic LNs and LNR in level II, simultaneous 3-level metastasis (level II, III, and IV), and 3-level with ≥ 2.5 metastatic LNs in level II were significantly associated with level V metastasis. (P = 0.011, 0.001, 0.003, and 0.002, respectively). In the future, larger-scale multi-institutional studies were needed to find out predictors for level V metastasis.

Management of Lateral Multiple-Level Metastasis in N1b Papillary Thyroid Microcarcinoma

Background: The optimal extent of therapeutic lateral neck dissection (LND) in the management of N1b papillary thyroid microcarcinoma (PTMC) is still under debate in clinical practice. In this light, our study aims to explore the incidence, patterns, and predictive factors of the lateral multiple-level metastasis in N1b PTMC patients. Methods: The clinical records of 142 patients diagnosed with N1b PTMC who underwent therapeutic LND from July 2015 to November 2018 at our institution were retrospectively reviewed. Univariate and multivariate analyses were conducted to examine the predictive factors associated with lateral multiple-level metastasis. The recurrence-free survival was analyzed and confirmed by Kaplan-Meier plots and log-rank test. Results: The overall frequency of lateral multiple-level metastasis was 50.7% in N1b PTMC patients, and two-level to four-level simultaneous metastasis were present in 26.8, 17.6, and 6.3% patients, respectively. Extrathyroidal extension (ETE) (OR = 5.79, 95% CI, 1.36-24.59; P = 0.017) and the central metastatic lymph node ratio (CLNR) with values equal or higher than 0.61 (OR = 6.18, 95% CI, 2.53-15.09; P < 0.001) served as independent predictors of multiple-level metastasis in N1b PTMC patients. Moreover, locoregional recurrence was significantly higher in the selective neck dissection (SND) group compared to the modified radical neck dissection (MRND) one (HR = 3.65, 95% CI, 1.11-12.00; P = 0.03). Conclusion: Our results show that the lateral multiple-level metastasis was relatively common, and we suggest MRND to be considered for N1b PTMC patients with ETE or CLNR equal or higher than 0.61.

Prediction of level V metastases in papillary thyroid microcarcinoma: a single center analysis

Background

The rate of level V metastases is significantly low and the necessity of routine level V dissection for papillary thyroid microcarcinoma (PTMC) with clinically lateral lymph node metastasis (LNM) is still controversial.

Methods

This study enrolled 114 consecutive PTMC patients with clinically suspected lateral LNM (N1b) who underwent modified radical neck dissection (levels II to V) at Xiangya Hospital of Central South University from September 2016 to July 2019. Univariate and multivariate analyses were performed to investigate the predictive factors of level V metastasis. The area under the receiver operating characteristic (ROC) curve (AUC), accuracy, specificity and sensitivity were used to determine the predictive value.

Results

The overall and occult rate of level V metastasis were 29.82% (34/114) and 7.02% (8/114), respectively. Univariate analysis showed that level V metastasis was significantly associated with gross extrathyroidal extension (ETE), level IV metastasis and 2-level simultaneous metastasis (all P<0.05). Gross ETE (OR =11.916, 95% CI, 1.404-102.19; P=0.023) and level IV metastasis (OR =8.497, 95% CI, 2.119-34.065; P =0.03) served as independent predictors of level V metastasis in N1b PTMC patients. The sensitivity, specificity, accuracy, positive predictive value (PPV) and negative predictive value (NPV) of gross ETE and level IV metastasis in predicting the level V metastasis were 25.3% vs. 82.4%, 97.5% vs. 73.8%, 82.69% vs. 76.32%, 80% vs. 57.04% and 75% vs. 90.77%, respectively. The AUC of gross ETE was lower than level IV metastasis (0.605 vs. 0.781, P=0.041).

Conclusions

Routine level V dissection is necessary in N1b PTMC patients with level IV metastasis or gross ETE. Compared with gross ETE, level IV metastasis is superior in predicting level V metastasis.

Clinicopathologic characteristics and outcomes of papillary thyroid carcinoma in younger patients

In the 7th edition of AJCC staging system, cervical lymph node metastases (LNM) in papillary thyroid carcinoma (PTC) is considered as a poorer prognostic indicator only in patients aged 45 years or older, but as a low-risk factor in patients younger than 45 years. The objective of this study is to investigate the influence of cervical LNM on prognostic outcomes of young patients (<45 years' old) with PTC.We carried out a retrospective analysis of 1896 PTC patients younger than 45 years' old at diagnosis, who were firstly treated in our department between January 2005 and December 2014. Clinicopathologic features, recurrences, disease-free survival (DFS) were recorded and analyzed.A total of 1896 consecutive patients were identified, comprising of 426 males and 1470 females after a median follow-up period of 40 months (3-129 months) from initial surgery to disease recurrence or to the end of follow-up. The rate of recurrence was 2.16% (n = 41). The DFS rates for a 1-year, 3-year, or 5-year team were 99.1%, 97.8%, or 97.4%, respectively. Univariate analysis showed that diagnosed age ≤30 years, tumor size >1.0 cm, extrathyroidal extension, multifocal lesions, lesions in bilateral lobes, central neck LNM, and lateral neck LNM were associated with a worse DFS. Multivariate analysis showed that only central neck LNM and lateral neck LNM were significant independent prognostic factors for DFS (P < .001). For patients with papillary thyroid microcarcinoma, cervical LNM were also identified as independent risk factors for DFS (P < .001).LNM have prognostic significance for DFS in PTC patients younger than 45 years. It indicated that PTC patients (<45 years old) with LNM, especially lateral neck LNM, were understaged by the 7th edition of AJCC staging system. Thus, radical resection of primary tumor and metastatic lymph nodes, frequent follow-up, and strict TSH suppression should be taken for young patients with PTC.

Transaxillary robotic modified radical neck dissection: a 5-year assessment of operative and oncologic outcomes

BACKGROUND

Robotic modified radical neck dissection (MRND) using a gasless transaxillary approach has been reported to be a safe and meticulous technique in patients with papillary thyroid carcinoma (PTC) and lateral neck node metastasis (N1b). Few studies, however, have attempted to assess the long-term oncologic outcomes of robotic MRND in these patients. This study aimed to compare perioperative and 5-year oncologic outcomes of robotic MRND with conventional open procedures in patients with N1b PTC.

METHODS

Between September 2007 and February 2010, 193 patients with N1b PTC underwent total thyroidectomy and MRND by a single surgeon. Of these, 42 (21.8 %) underwent robotic procedures and 151 (78.2 %) underwent conventional open procedures. All patients received 3.7- to 5.5-GBq radioactive iodine (RAI) ablation, post-therapy whole-body scans (TxWBSs), and diagnostic WBS (DxWBSs) during follow-up. An exact 1:3 matching for age and stage was performed to minimize selection bias, and perioperative and 5-year oncologic outcomes were compared in the matched groups.

RESULTS

The mean follow-up period was 66.0 months (range 60-90 months). Number of retrieved cervical lymph nodes (LNs) (p = .102) and postoperative ablation success rates (p = .864) were similar between the two groups. TSH-suppressed serum Tg concentrations after 5 years (0.7 ± 1.5 vs. 2.4 ± 14.1 ng/ml; p = .471) and recurrence rates in the robotic and open groups (1/41 [2.4 %] vs. 3/102 [2.9 %]; p = .864) were similar for the 5-year follow-up period. Four patients experienced recurrence: Three exhibited regional lymph node metastasis, and one showed bilateral lung metastases.

CONCLUSION

The perioperative and 5-year oncologic outcomes were similar after robotic and conventional open MRND. Large, prospective randomized controlled trials with long-term follow-up data are needed to validate these results.

Dissection of Levels II Through V Is Required for Optimal Outcomes in Patients with Lateral Neck Lymph Node Metastasis from Papillary Thyroid Carcinoma

BACKGROUND

Completeness of surgical resection is an important determinant of outcomes in patients with papillary thyroid carcinoma and regional lymph node metastasis. The extent of therapeutic lateral neck dissection remains controversial. This study aims to assess the impact of modified radical neck dissection of levels II to V in a large patient series.

STUDY DESIGN

Retrospective analysis of consecutive patients with papillary thyroid carcinoma who underwent lateral neck dissection at a single institution from June 1, 2006 to December 31, 2014 was performed.

RESULTS

A total of 241 lateral neck dissections were performed in 191 patients (118 [62%] women; median age 46 years [range 6 to 87 years]; median follow-up 14.3 months [range 0.1 to 107 months]). Overall, 202 initial neck dissections (195 modified radical neck dissections and 7 less extensive dissections) were performed. Among these initial dissections, 137 (68.8%), 132 (65.7%), 105 (52.0%), and 33 (16.9%) had positive lymph nodes in levels II, III, IV, and V, respectively. Ipsilateral lymph node persistence or recurrence occurred after 22 (10.9%) initial dissections, at level II in 10 (45.5%), level III in 8 (36.4%), level IV in 7 (31.8%), and level V in 3 (13.6%). Thirty-nine reoperative lateral neck dissection were performed, including 18 cases of persistence and recurrence after our initial dissections. In reoperative dissections, positive lymph nodes were confirmed in levels II, III, IV, and V in 18 (46.2%), 10 (25.6%), 13 (33.3%), and 5 (12.8%) dissections, respectively. Temporary nerve injury occurred in 6 (3.0%) initial and 4 (10.3%) reoperative dissections, respectively. There were no permanent nerve injuries.

CONCLUSIONS

Omitting levels II and V during lateral neck dissection for papillary thyroid carcinoma potentially misses level II disease in two-thirds of patients and level V disease in one-fifth of patients. Formal modified radical neck dissection is necessary to avoid the morbidity of reoperative surgery.