The authors have no funding, financial relationships, or conflicts of interest to disclose.
Triological Society Best Practice
What is the appropriate extent of lateral neck dissection in the treatment of metastatic well-differentiated thyroid carcinoma?†
Version of Record online: 24 AUG 2010
Copyright © 2010 The American Laryngological, Rhinological, and Otological Society, Inc.
Volume 120, Issue 9, pages 1716–1717, September 2010
How to Cite
Hasney, C. P. and Amedee, R. G. (2010), What is the appropriate extent of lateral neck dissection in the treatment of metastatic well-differentiated thyroid carcinoma?. The Laryngoscope, 120: 1716–1717. doi: 10.1002/lary.20994
- Issue online: 24 AUG 2010
- Version of Record online: 24 AUG 2010
- Manuscript Accepted: 13 APR 2010
The evidence presented was obtained from five evidence-based medicine level 4 studies.
Although cervical metastases occur in a significant number of cases, the extent of therapeutic neck dissection in the setting of metastatic WDTC remains unclear. Recently published American Thyroid Association (ATA) guidelines recommend dissecting both the central and lateral lymph node compartments in the presence of clinically or histologically apparent lateral cervical metastases. Even though these guidelines explicitly define the central compartment dissection as the removal of level VI, the levels to be addressed in the lateral neck are not clearly stated.1 Modified radical neck dissection and selective neck dissection, including levels II-A, III, and IV, have been advocated, but no official management guidelines exist. At the root of this controversy is the question of whether or not to routinely dissect levels II-B and V, considering the potential morbidity due to injury to the spinal accessory nerve while dissecting these nodal basins.
In this review, we summarize the recent literature regarding the extent of lateral neck dissection in the setting of metastatic WDTC and seek to define the current best clinical practices based on the available evidence.
The most recent ATA management guidelines for patients with thyroid nodules and differentiated thyroid cancer offer explicit recommendations for the management of the central neck in patients with clinical or radiographic evidence of nodal metastases (therapeutic neck dissection) and in those without evidence of nodal disease (elective or prophylactic neck dissection). However, these guidelines are notably vague in their recommendations for management of lateral neck metastases. The ATA guidelines advocate functional compartmental en bloc lateral neck dissection in patients with biopsy-proven metastatic lateral cervical lymphadenopathy but offer no official recommendation concerning which nodal basins to address.1
Convincing clinical evidence exists regarding the pattern of spread through the cervical lymphatics of WDTC.2 The finding that levels II-A, III, and IV are most commonly affected lends support to the use of selective lateral neck dissection in the setting of metastatic WDTC. However, level V has been shown to be involved with WDTC in a substantial percentage of cases and is not addressed by a standard selective lateral neck dissection. In 2006, Caron and colleagues addressed the role of routine dissection of levels I, II, and V in the setting of metastatic papillary thyroid carcinoma. Analyzing patients who had undergone selective neck dissection of levels III and IV, including levels I, II and/or V, the authors found recurrences at levels I and V to be uniformly uncommon, whereas recurrences at level II occurred in 21% ipsilaterally and 14% contralaterally with no difference in the recurrence rate between those who underwent resection of level II and those who did not.3 Based on these findings, recommendations to forego elective dissection of levels I and V and to dissect level II in cases of clinical or radiographic evidence of disease, signs of aggressive local disease, extensive contiguous level III disease, or bilateral disease were set forth.
Despite Caron and colleagues' recommendation to avoid elective dissection of level V, a study from the M.D. Anderson Cancer Center offered a set of preoperative variables as potential predictors of level V metastasis. Multifocal disease and ipsilateral metastases in levels II, III, and IV were identified as significant predictors of level V disease. Interestingly, preoperative imaging, specifically ultrasound and axial imaging, were found to be insensitive for detecting metastatic disease in level V.4 Within the study group, 53% harbored biopsy-proven disease at level V. These results led to the recommendation of elective dissection of levels II–V in all patients with metastatic WDTC.
Considering the evidence both for and against dissection of level V in this patient population, Farrag and colleagues analyzed the utility of routine dissection of level V-A and level II-B. In their retrospective review, the authors sought to define the role of elective dissection of these levels by determining the frequency of involvement of each level. Of 60 specimens, metastatic WDTC was identified in 60% of level II-A, 8.5% of II-B, 66% of III, 50% of IV, 0% of V-A, and 40% of V-B. These findings then led to the recommendations to electively dissect level II-B only when II-A is involved with disease, and to electively dissect V-B in all cases while universally refraining from elective dissection of V-A.5
The available evidence for management of the lateral neck in metastatic WDTC is somewhat inconsistent. In the absence of a recognized consensus statement on the topic, multiple therapeutic options remain viable. Evidence exists for employing both selective neck dissection, including levels II–V, with or without the inclusion of levels II-B and V-A, and modified radical neck dissection in this setting. One should remain aware of the fact that the presence of nodal disease is associated with an increased rate of locoregional recurrence, but no direct effect on overall survival has been established.4 Bearing this evidence in mind, one should proceed with the general approach of removing any clinically overt nodes by performing the most concise, least morbid operation.
LEVEL OF EVIDENCE
In this review, five level 4 studies (retrospective study without an internal control group) are cited.
- 1Revised American Thyroid Association management guidelines for patients with thyroid nodules and differentiated thyroid cancer: The American Thyroid Association (ATA) Guidelines Taskforce on Thyroid Nodules and Differentiated Thyroid Cancer. Thyroid 2009; 19: 1167–1214., , , et al.