Download Central Neck Dissection for Papillary Thyroid Cancer

Central neck lymph node dissection
is an important component in the
treatment of papillary thyroid cancer.
Rebecca Kinkead. Nadav and Sara (detail), 2009. Oil and alkyd on canvas, 45⬙ × 37⬙.
Central Neck Dissection for Papillary Thyroid Cancer
David T. Hughes, MD, and Gerard M. Doherty, MD
Background: Central compartment lymph node dissection is a common adjunct to thyroidectomy in the treatment
of papillary thyroid cancer. The indications, surgical technique, potential benefits, and operative risks of this
procedure should be clearly defined in order to provide optimal care to these patients.
Methods: A systematic review of the literature and an analysis of evidence-based recommendations were performed
regarding central neck node dissection for patients with papillary thyroid carcinoma.
Results: Cervical nodal metastasis in papillary thyroid cancer is a common occurrence. The presence of metastasis
is associated with increased recurrence rates and may decrease survival. Detection of central and lateral neck
nodal metastasis preoperatively with clinical examination and cervical ultrasound is important in determining
the appropriate initial surgical management. Level VI neck dissection and central neck dissection are terms
often used interchangeably to describe surgical excision of all lymph nodes from the hyoid bone to the sternal
notch between the carotid arteries, but the addition of the superior mediastinal lymph nodes in compartment
VII should be included in the central neck dissection. Due to improved recurrence rates and survival, therapeutic
central neck dissection is recommended for all patients with nodal involvement detected pre- or intraoperatively.
Prophylactic central neck dissection in patients without detectable nodal disease remains a controversial topic due
to a lack of definitive evidence of improved recurrence rates or survival and the possibility of higher complication
rates compared to total thyroidectomy alone. Reoperative central nodal dissection can be a challenging procedure
with increased complication rates but with good outcomes in experienced centers.
Conclusions: Central neck lymph node dissection plays an important role in the appropriate treatment of papillary
thyroid cancer at initial presentation and in cases of recurrent disease. Surgeons caring for this group of patients
should have familiarity and skill with this procedure.
Introduction
From the Department of Surgery at the University of Michigan,
Ann Arbor, Michigan. Dr Hughes is now with Montefiore Medical
Center/Albert Einstein College of Medicine, Bronx, NY.
Submitted February 24, 2010; accepted April 16, 2010.
Address correspondence to David T. Hughes, MD, Montefiore Medical
Center/Albert Einstein College of Medicine, 1400 Bainbridge Avenue,
Bronx, NY 10467. E-mail: [email protected]
No significant relationship exists between the authors and the companies/organizations whose products or services may be referenced
in this article.
April 2011, Vol 18, No. 2
Papillary thyroid cancer is the most common form of
differentiated thyroid cancer, comprising approximately
90% of the 44,670 estimated new cases of thyroid cancer
in the United States in 2010.1 The established primary treatment of papillary thyroid cancer per American Thyroid
Association (ATA) guidelines is total thyroidectomy
for all tumors larger than 1 cm, while thyroid lobectomy
is sufficient for tumors smaller than 1 cm.2 The ATA
consensus statement also recommends therapeutic
central neck dissection in patients with clinically involved
nodes and prophylactic central neck dissection in advanced primary tumors (T3 or T4) without evidence of
Cancer Control 83
nodal involvement.2 Radioactive iodine ablation plays an
important role in adjuvant treatment following thyroidectomy for some subgroups of patients based on risk of
recurrence.2 This treatment algorithm achieves extremely
low death rates; however, the rates for cervical lymph
node metastasis and recurrence remain significant. Despite the ATA recommendations, there is controversy regarding the ideal surgical management of the central neck
lymph nodes in patients with papillary thyroid cancer.
Nodal Metastasis in Papillary Thyroid Cancer
Incidence and Relevance
Papillary thyroid cancer and the follicular variant of
papillary thyroid cancer have a propensity for cervical
lymphatic spread that occurs in 20% to 50% of patients
on standard review of surgical pathologic specimens and
in 90% of those examined for micrometastases.3,4 The
spread of tumors cells occurs in a predictable pattern
that initiates in the perithyroidal lymph nodes of the
central neck and progresses to the lymph nodes of the
lateral cervical compartments and the superior mediastinum.5,6 “Skip” metastases to the lateral compartment
Fig 1. — Lymph node compartments of the neck. Level VI and VII are
included in central neck dissection, while lateral neck dissection typically
includes levels II–V for treatment of papillary thyroid cancer. From American Thyroid Association Surgery Working Group, American Association of
Endocrine Surgeons, American Academy of Otolaryngology-Head and Neck
Surgery, et al. Consensus statement on the terminology and classification
of central neck dissection for thyroid cancer. Thyroid. 2009;19(11):11531158. Courtesy of Mary Ann Liebert, Inc.
84 Cancer Control
without central neck nodal involvement are rare but
do occur.5,6 Patients with nodal metastasis have higher
rates of persistent and recurrent disease during postoperative surveillance.6 The impact of nodal metastasis on
overall survival remains debatable; several studies have
demonstrated no difference in mortality, while two large
population-based studies have shown increased mortality in patients with regional lymph node metastasis.7-11
Detection of Nodal Metastasis
The initial approach to a patient with a thyroid nodule
should include a detailed examination of the thyroid
and the cervical lymph node compartments. The classification system of cervical lymph node compartments
is well defined and is important not only in identifying
the location of pathologic lymph nodes, but also in planning surgical treatment as outlined and illustrated in the
recent ATA guidelines for management of thyroid cancer
(Fig 1).2,12,13 Patients with papillary thyroid cancer occasionally present on initial assessment with palpable
cervical lymphadenopathy, which is most often located
in the central neck or levels III and IV of the lateral neck,
usually in conjunction with an ipsilateral thyroid nodule.
Cervical ultrasound, often performed as an officebased examination, is the primary imaging modality for
the initial assessment as well as the postoperative surveillance of patients with papillary thyroid cancer. Highresolution ultrasonography can detect cervical nodal
metastasis in 14% to 20% of papillary thyroid cancer
patients and can detect pathologic nodes as small as
2 to 3 mm without the risks associated with radiation
exposure.14,15 Ultrasound is also easily repeatable and
has been shown to change the surgical procedure performed in 39% of thyroid cancer patients.14,15 A dedicated
cervical ultrasound to include nodal levels II–VI should
be performed, ideally by a dedicated clinician such as
the thyroid endocrinologist, the operating surgeon, or a
radiologist with particular interest, to detect nonpalpable
lymph node metastases in patients undergoing surgical
evaluation for any thyroid nodule (Fig 2). The sensitivity
Fig 2. — Ultrasonic appearance of level III lymph node with papillary thyroid
cancer metastasis using 12.5 MHz linear transducer. Note the irregular border
of the lymph node and the lack of the normal hyperechoic hilar line.
April 2011, Vol 18, No. 2
of cervical ultrasound to detect pathologic lymph nodes
in papillary thyroid cancer patients is higher in the lateral
neck (94%) than in the central neck (53% to 55%), and
this disparity may be considered as additional support
for prophylactic central neck dissection.16 Pathologic
lymph node metastasis detected on ultrasound can be
confirmed with ultrasound-guided fine needle aspiration.
In patients with suspected mediastinal disease or with
bulky cervical lymphadenopathy, cross-sectional imaging
with CT should be considered as it can aid in the planning of nodal dissection and often identifies pathologic
level VI and VII lymph nodes within the superior mediastinum that are not detected on cervical ultrasound or
physical examination.
Operative Considerations for
Central Neck Lymph Node Dissection
Technique
Cervical nodal dissection for papillary thyroid cancer
should include a systematic or en bloc nodal basin dissection rather than a selective or “berry picking” dissection
due to higher rates of persistent and recurrent disease
with the later approach.17 The ATA consensus statement12
regarding the terminology and classification of the central
neck defines the central compartment nodal dissection
as all perithyroidal and paratracheal soft tissue and lymph
nodes with borders extending superiorly to the hyoid
bone, inferiorly to the innominate artery, and laterally
to the common carotid arteries and is well described
and illustrated by Grodski et al18 (Fig 3). The inclusion
of the level VII nodes in the superior mediastinum with
the central neck dissection should be noted as this is
often a site of persistent disease following central neck
dissection. Moo et al19 compared ipsilateral vs bilateral
central neck dissection for papillary thyroid cancer and
concluded that an ipsilateral dissection was sufficient in
tumors less than 1 cm, while tumors larger than 1 cm
required bilateral central neck dissection based on the
high incidence of contralateral central neck disease in a
retrospective analysis of the pattern of nodal metastases in
surgical specimens. Some additional studies demonstrated that ipsilateral central neck dissection was adequate for
tumors larger than 1 cm.20 If lateral cervical metastases
are present in levels II–V, a bilateral central nodal dissection should be included with the modified radical neck
dissection to remove the presumed central neck nodal
disease based on described patterns of nodal spread.21
Complications
Complications of central neck dissection include injury
to the recurrent laryngeal nerve or the external branch
of the superior laryngeal nerve, which occurs in 1% to
2% of patients based on several studies.20,22-25 Small retrospective studies have shown that the addition of central
compartment lymphadenectomy to total thyroidectomy
for thyroid cancer has not increased nerve injury rates
in experienced hands.20,22,23,26 In cases of reoperative
central lymph node dissection after either previous
thyroidectomy or central node dissection, reports have
noted increased nerve injury rates ranging from 1% to
12%.24,25,27-29 Temporary hypoparathyroidism following
central neck dissection occurs in 14% to 40% of cases
depending on the definition of hypoparathyroidism used
in the study.20,22,23,30-33 The higher incidence of temporary hypoparathyroidism is likely due to the increased
incidence of parathyroid reimplantation and inadvertent
inclusion of parathyroid glands in the nodal dissection.
Reports are mixed regarding the risk of permanent hypoparathyroidism. A meta-analysis of retrospective studies
reported a 1.2% incidence as defined by the requirement
for calcium supplements greater than 6 to 12 months
postoperatively; however, none showed a statistically
significant difference in total thyroidectomy with or without central neck dissection.34
Situational Considerations
Fig 3. — Right-level VI lymph node dissection including all perithyroidal
and paratracheal soft tissue and lymph nodes. Judicious use of parathyroid
reimplantation should be utilized with regard to the lower parathyroid
glands. From Grodski S, Cornford L, Sywak M, et al. Routine level VI lymph
node dissection for papillary thyroid cancer: surgical technique. ANZ J
Surg. 2007;77(4):203-208. Reprinted with permission of John Wiley and
Sons, Inc.
April 2011, Vol 18, No. 2
Therapeutic Central Neck Dissection
Pathologic lymph node involvement noted on preoperative clinical or imaging assessment is a well-established
indication for therapeutic lymph node dissection.2 A
careful search for the presence of pathologic central compartment lymph nodes with both physical examination
and cervical ultrasound is critical during preoperative
assessment. The presence of pathologic level VI lymph
nodes should prompt detailed physical and ultrasonic
examination of the lateral cervical nodal chains for additional evidence of metastasis. Suspicion of lymph node
Cancer Control 85
involvement can be confirmed with fine needle aspiration biopsy. The surgical technique for therapeutic nodal
dissection should include both the ipsilateral and the
contralateral central compartments. The lymph node
dissection specimen should be excised en bloc during
thyroidectomy. Any incidental note of suspicious nodes
in the lateral neck should prompt biopsy and frozen section analysis for confirmation of cancer involvement. If
cancer is present in any lateral neck nodes, the dissection
should be extended to an ipsilateral modified radical neck
dissection to include levels II–V.35-37 Liberal application
of parathyroid reimplantation during central neck dissection should be employed to prevent postoperative
hypoparathyroidism.20
There are several goals in the use of nodal dissection
for clinically evident locoregional lymph node metastasis
in papillary thyroid cancer. The primary intent is locoregional control of disease, given the correlation of nodal
metastasis with significant increases in persistent and
recurrent disease.6,8,38,39 Several studies have demonstrated decreased recurrence rates and improved survival when the burden of cervical disease is removed via
therapeutic neck dissection.15,33,40 In patients with known
distant metastatic disease, the debulking of cervical disease for palliative purposes is beneficial in preventing
local complications.
Prophylactic Central Neck Dissection
Prophylactic or routine central neck dissection for patients with papillary thyroid carcinoma is defined as
complete excision of the level VI and VII lymph nodes
in patients with no evidence of nodal involvement after
preoperative clinical and imaging evaluation. The role of
prophylactic central neck dissection remains a contentious issue regarding its benefits and risks, and several
reports have reviewed this subject.41-43 Several singleinstitution retrospective cohort studies on total thyroidectomy alone vs with prophylactic neck dissection, as
well as a meta-analysis of these studies, have reported
mixed results.20,22,23,30,31,34
Proponents of prophylactic central neck dissection
at the time of initial thyroidectomy cite the high incidence of cervical lymph node metastasis and the associated increase in recurrence rates with the possibility of
decreased survival. The low sensitivity of preoperative
ultrasound evaluation and intraoperative assessment to
accurately detect lymph node involvement is also used
as rationale for routine central neck dissection.15,38,44
The addition of central neck dissection to initial total
thyroidectomy can provide valuable staging information and has been shown to upstage approximately a
third of patients older than 45 years of age to stage III
disease in two retrospective reviews.45,46 This upstaging has important implications for further treatment as
those with nodal metastasis are likely to receive higher
doses of I131 ablation treatment, while those with small,
86 Cancer Control
noninvasive tumors without nodal disease can forgo I131
ablation. The evidence to support prophylactic dissection due to decreased recurrence rates and improved
survival is sparse and is primarily composed of a prospective population-based study from Sweden.47 This
study demonstrated that the rate of death due to thyroid
cancer, which ranged from 8.4% to 11.1%, was reduced to
1.6% in patients who underwent central neck dissection
compared to contemporary controls. However, several
retrospective cohort studies have shown no difference
or only a slight improvement in recurrence or survival
rates.36,48-50 While an additional benefit of reduced postoperative thyroglobulin levels after central neck dissection was demonstrated by Sywak et al,20 a recent study
at our institution showed no difference in thyroglobulin
levels between total thyroidectomy or total thyroidectomy with central neck dissection.46 In patients with
known distant metastasis without evidence of cervical
nodal involvement, a prophylactic neck dissection to
include both the central neck and the ipsilateral lateral
neck has been recommended by some due to the high
rates of nodal involvement in this group of patients on
histological analysis.51 Overall, the addition of prophylactic central neck dissection appears to provide important
staging information that can affect radioactive iodine
ablative treatment, but the evidence regarding recurrence
and survival benefits remains limited and conflicted.
The arguments against prophylactic central lymph
node dissection at the time of initial thyroidectomy for
papillary cancer focus on the unproven benefit and the
possibility of increased complications. The relevance of
subclinical cervical lymph node metastasis on rates of
recurrence and survival has been questioned by some retrospective studies.50 Additionally, there is a lack of proven
benefit in outcomes after prophylactic central node dissection. The possibility of increased complication rates
with central neck dissection has been addressed, although
again by only small retrospective cohort studies.20-23,26,31,52
Higher rates of temporary hypoparathyroidism with central neck dissection seem consistent between these studies, while the rates of permanent hypoparathyroidism
and nerve injury rates are statistically similar compared
with total thyroidectomy alone.34,42 The debate on the
role of routine central neck dissection in the treatment
of papillary thyroid carcinoma is likely to continue until
a large randomized trial with long-term follow-up can
be completed.
Reoperative Central Neck Dissection
Reoperative central neck dissection is defined as removal
of all remaining soft tissue in the level VI and VII compartments in a patient who has undergone previous thyroidectomy or central lymph node dissection. This is often
indicated for patients with papillary thyroid cancer who
are noted to have central neck lymph node involvement
on surveillance examination or imaging studies after comApril 2011, Vol 18, No. 2
References
Fig 4. — CT imaging demonstrating a superior mediastinal lymph node
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lymphadenopathy in the lateral neck and superior mediastinum. Combining imaging modalities with cervical
ultrasound and cross-sectional imaging with CT or PET/
CT can help to guide operative planning and to determine
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detected with cross-sectional imaging and can usually
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of the central compartment lymphadenectomy (Fig 4).
Preoperative laryngoscopy should be performed before
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of reoperative neck dissection, consideration of recurrent
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the parathyroid vascular pedicles originating from the
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Central neck dissection is the most common neck dissection completed for patients with papillary thyroid
cancer and can be performed safely and effectively with
low complication rates by experienced surgeons. Therapeutic central neck dissection is recommended for all
patients with clinically evident disease. Prophylactic
central neck dissection should be considered in order
to provide more accurate staging in high-risk patients.
However, conclusive data are lacking regarding its influence on recurrence, survival, and complication rates.
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