|Year : 2019 | Volume
| Issue : 1 | Page : 48-53
Role of central lymphadenectomy in managment of differentiated thyriod cancer
Mohammed Mamdoh Ahmed Asar1, Mohamed Kamel El Awady2, Ahmed Seddik Abdelgelil2, Mohammed El Sharkawy2, Osama Mostfa Mostafa3
1 Department of General Surgery (Surgical Oncology Subunit), Al-Azhar University, Cairo, Egypt
2 Department of Otorhinolaryngology, Al-Azhar University, Cairo, Egypt
3 Pathology, Faculty of Medicine, Al-Azhar University, Cairo, Egypt
|Date of Submission||27-Nov-2018|
|Date of Acceptance||20-Mar-2019|
|Date of Web Publication||12-Sep-2019|
Mohammed Mamdoh Ahmed Asar
Lecturer of General Surgery (Surgical Onocology Subunite), Faculty of Medicine, Alazahar University, 6 October, Cairo
Source of Support: None, Conflict of Interest: None
Background Differentiated thyroid cancers may be associated with regional lymph node (LN) metastases in 20–50% of cases. Papillary thyroid cancer is the most common thyroid malignancy, and cervical nodal metastases are frequent at presentation.
Objective This study aims to detect the therapeutic and prophylactic results of centeral neck dissection (CND) in an adjunct to total thyroidectomy for the treatment of differentiated thyroid cancer and its effect in reducing local recurrences and the need for postoperative radioiodine ablation.
Patients and methods This study was carried out on 30 patients with thyroid cancers. They were managed at Oncological Surgery Departments of Al-Azhar University between January 2017 and August 2018. This study included 30 patients, comprising 10 (33.3%) males and 20 (66.6%) females, and their ages ranged from 26–82 years old, with a mean age of 51 years. They all underwent total thyroidectomy and CND for differentiated thyroid cancer, which was proved preoperatively by fine-needle aspiration from thyroid swelling. Neck ultrasound and high-resolution neck computed tomographic scan with contrast were done to detect size and extension of thyroid cancer and any concerning LNs.
Results The analysis of nodal spreading in this study showed an ipsilateral central nodal metastasis on the same side of affected lobe and bilateral central LN metastasis when the tumor arose within each lobe or from isthmus, as the lesions from isthmus had wide diffusion. Moreover, this study showed tumors with size of 20 less than or equal to T2 less than 40 mm associated with the presence of LN metastases were subjected to postoperative 131I ablation, and also a size greater than or equal to 40 mm with vascular invasion or tumor extension beyond the thyroid capsule even not associated with the presence of LN metastases were subjected to postoperative 131I ablation.
Conclusion Prophylactic central compartment neck dissection (ipsilateral or bilateral) should be considered in patients with differentiated thyroid cancer (DTC) with clinically noninvolved central neck LNs (cN0) who have locally advanced primary tumors (T3 or T4), and prophylactic ipsilateral CND and lateral neck dissection for DTC less than 2 cm in diameter allowed selection of patients for postoperative 131I ablation and modified the indication for 131I ablation in patients with pT1 tumors.
Keywords: central lymphadenectomy, neck dissection, thyroid cancer
|How to cite this article:|
Asar MA, El Awady MK, Abdelgelil AS, El Sharkawy M, Mostafa OM. Role of central lymphadenectomy in managment of differentiated thyriod cancer. Al-Azhar Assiut Med J 2019;17:48-53
|How to cite this URL:|
Asar MA, El Awady MK, Abdelgelil AS, El Sharkawy M, Mostafa OM. Role of central lymphadenectomy in managment of differentiated thyriod cancer. Al-Azhar Assiut Med J [serial online] 2019 [cited 2020 Jun 2];17:48-53. Available from: http://www.azmj.eg.net/text.asp?2019/17/1/48/266730
| Introduction|| |
Differentiated thyroid cancers may be associated with regional lymph node (LN) metastases in 20–50% of cases. Cervical LN levels VI and the upper part of VII (central compartment) are often involved in thyroid malignancy. Papillary thyroid cancer (PTC) is the most common thyroid malignancy, and cervical nodal metastases are frequent at presentation. The most common site for nodal metastases from PTC is the central compartment of the ipsilateral side of the neck in the paratracheal and pretracheal regions ,.
The decision to resect these LNs at the time of thyroidectomy often depends on if nodes with suspected malignancy can be identified preoperatively. If nodal spread to the central neck nodes is known, then the consensus is to remove all nodes in this area. However, there remains significant controversy regarding the utility of removing central neck LNs for prophylactic reasons .
Preoperatively, patients should undergo a clinical neck examination in combination with a high-resolution neck ultrasound to detect any concerning LNs. Unfortunately, LNs in the central neck compartment are more difficult to image via ultrasound when compared with the lateral neck owing to their proximity to the thyroid gland and air-filled trachea .
Ahn et al.  found that the sensitivity of ultrasound for detection of lateral compartment LNs was 94%, compared with 53–55% in the central neck.
Ultrasound criteria, which typically include a cystic component or hyperechoic punctuations, do not always need confirmation by fine needle aspiration (FNA). Other less-specific ultrasound characteristics, including a round shaped and loss of a hilum, may raise enough suspicion where FNA may be beneficial. If, at the time of thyroidectomy, firm, enlarged, or discolored LNs are identified, the decision can be made to complete central neck dissection (CND) to clear all potential LN metastases .
In the latest guidelines published by the European Thyroid Association, compartment-oriented microdissection of LNs is recommended for LNs that are suspected preoperatively and/or LN metastases detected intraoperatively with a positive pathologic examination .
The rationale for this recommendation is based on the evidence that radical primary surgery has a favorable effect on survival in high-risk patients and on the recurrence rate in low-risk patients ,.
Factors supporting CND are (a) accurate staging of disease to plan the best treatment and follow-up, (b) changing radioiodine treatment indication or dosing, (c) decreased rates of local recurrence and the potential morbidity of reoperation, and (d) possible improvement in overall survival ,.
Surgery is becoming the mainstay of treatment of differentiated thyroid cancer but should be performed by trained surgeons, to diminish its long-term adverse effects, mostly permanent hypoparathyroidism .
The most important morbidities associated with CND consist of recurrent laryngeal nerve damage and hypocalcemia related to parathyroid hypofunction or to accidental parathyroidectomy. The incidence of surgical complications is variable, is surgeon and center dependent, and correlates with pathological features of the tumor ,.
| Aim of the work|| |
This study aims to detect the therapeutic and prophylactic results of CND as an adjunct to total thyroidectomy for the treatment of differentiated thyroid cancer and its effect in reducing local recurrences and the need for postoperative radioiodine ablation.
| Patients and methods|| |
This study was carried out on 30 patients with thyroid cancer, comprising ten (33.3%) males and 20 (66.6%) females, and their ages ranged 26–82 years old, with mean age of 51 years. They underwent total thyroidectomy and CND for differentiated thyroid cancer, which was proved by fine-needle aspiration from thyroid swelling. They were managed at Oncological Surgery Departments, Bab −Elshaeria Hospital of Al-Azhar University between January 2017 and August 2018.
All patients suspected to have differentiated thyroid cancer were subjected to the following:
- Full history taking including personal history, family history, and past history to determine the onset and duration of symptoms, and any palpable neck LN.
- Clinical neck examination for thyroid cancer and any palpable LN in either central or lateral group.
- High-resolution neck ultrasound to detect size and extension of thyroid cancer and any concerning LNs.
- Thyroid function tests.
- High-resolution neck computed tomographic (CT) scan with contrast from skull base to upper part of the chest to detect size and extension of thyroid cancer and central LN that cannot be clinically detected.
- Cytological analysis by FNA of the thyroid swelling and palpable LN of lateral group if possible especially in high-risk group patients to detect the type of malignancy.
- Postoperative histopathological examination for obtained thyroid gland and either or both central and lateral neck nodes.
Written informed consent was obtained for surgical options from all patients. CND was performed simultaneously during total thyroidectomy.
We performed a standard Kocher incision. The skin flaps were raised, and the strap muscles were dissected and separated to maximize lateral retraction. Visualization of the median intermuscular line allowed identification of LN, with the middle line (the Delphian and prelaryngeal LNs anterior to the cricothyroid membrane) leaving the loose fibro-fatty glandulo-stromal tissue adhering to the thyroid capsule.
After isolation and dissection of the strap muscles, total thyroidectomy was done in usual technique, and its details may be discussed elsewhere and not here.
The surgical boundaries of the central node compartment of the neck (compartment VI) had been well dissected intraoperatively. We dissected the prelaryngeal Delphian node region plus the paratracheal LN between both carotid arteries and down to the upper part of the horn of the thymus. The pretracheal LNs present below the thyroid isthmus also had been dissected. On the right side, LNs are distributed both anterior and posterior to the recurrent laryngeal nerve, whereas on the left side, LNs lie anteriorly. Thus, dissection of the right side of compartment VI was technically more demanding than dissection of the left side. Surgical strategy may vary according to the experience of the surgeon, but we advise two precautions: (a) clearance of the paratracheal nodes is best performed by initially identifying the recurrent laryngeal nerve at the base of the neck and then proceed cranially and (b) the lower parathyroid glands should be identified and preserved before starting the LN dissection. This means that whenever possible the thymus horns should not be included in CND specimen, as this is associated with a higher prevalence of hypocalcemia. Thymus preservation should be the rule in prophylactic CND where the thyrothymic ligament is not involved by metastatic nodes, the normal anatomy was well preserved and the lower parathyroid glands could be more easily identified and kept in situ ([Figure 1] and [Figure 2]).
|Figure 1 Shows after completion of total thyroidectomy together with high cut of trap muscles for proper exposure of central zone.|
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|Figure 2 Shows central and ipsilateral lateral neck dissection. internal jugular vein and full dissection of RLN along it’s coarse.|
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[Figure 2] show the results after completion of total thyroidectomy together with CND and ipsilateral lateral neck dissection. As shown in this case, strap muscles were cut high for proper exposure of central zone with full dissection of recurrent laryngeal nerve (RLN) along its course.
All patients were subjected to the following:
- Serum calcium for assessment of parathyroid function.
- The whole-body radioactive iodine scanning to detect any residual tumor or other LN metastasis.
- Radioactive iodine therapy and external beam radiation in high-risk patients.
- After 6 months and 1 year, neck ultrasound and CT neck with contrast were done for all patients for detection of any type of recurrence.
| Results|| |
Between March 2016 and December 2017, 30 patients, comprising ten (33.3%) males and 20 (66.6%) females, with a median age 51 of years (26–82 years), underwent total thyroidectomy and CND for differentiated thyroid cancer, proved in fine-needle aspiration from thyroid swelling.
Results of operative finding and postoperative histopathological study of primary thyroid cancer
The mean size of differentiated thyroid cancer (DTC) on gross histopathological examination was 28.5 mm (range, 16–57 mm). The size of the DTC was less than 20 mm in 12 (39.6%) patients and was more than 20 mm and less than 40 mm in 10 (33.3%) patients, and the size of the DTC was more than 40 mm in eight (26.4%) patients. Tumor extension beyond the thyroid capsule with vascular invasion in three (9.9%) cases.
An operative finding of thyroid involvement by malignant focus was unilateral unifocal tumor in 15 (50%) patients, unilateral multifocal in ten (33%) patients, and multifocal and bilateral in five (16.5%) patients ([Table 1]).
Results of neck dissection
CND was performed for all the patients. The analysis of nodal spreading showed an ipsilateral central nodal metastasis on the same side of affected lobe and bilateral central LN metastasis when T disease arises within each lobe. Lesions from isthmus had wide diffusion, involving both sides and indifferently any areas. One (1.5%) patient had a contralateral nodal spread.
Lateral LN dissection of levels II–IV was performed ipsilaterally in ten (33.3%) cases when level II–IV LN are involved and bilaterally for five (16.5%) cases patients with differentiated thyroid cancer (DTC) arising in the isthmus or with bilateral multifocal tumors with suspicious criteria radiological or as an operative finding ([Table 2] and [Table 3]).
|Table 2 The side of neck lymph node dissection in relation to site and nature of thyroid cancer|
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|Table 3 Neck lymph node metastasis in thyroid cancer regarding histopathological examination|
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Postoperative radioiodine (131I) ablationIt varies according to the stage of both primary pathology (T1 or T2 or T3) and LN metastasis.
The results of this study showed that having age younger than 50 years and the presence of tumor size of 20 less than or equal to T2 less than 40 mm associated with the presence of LN metastases were subjected to postoperative 131I ablation. Moreover, tumors with size greater than or equal to 40 mm and the existence of vascular invasion or tumor extension beyond the thyroid capsule even not associated with the presence of LN metastases were subjected to postoperative 131I ablation ([Table 4]).
Postoperative follow-up for detection of complications or tumor recurrence
In the early postoperative period, there was one (3.3%) patient who developed laryngeal palsy, and three (9.9%) patients who developed definitive hypoparathyroidism requiring calcium and vitamin D supplementation. No patients developed collection or hematoma after surgery or wound infection. One year after surgery, there was no patient who showed suspicious cervical LN or primary site recurrence on ultrasound and CT scan of the neck in the short-term follow-up.
| Discussion|| |
Central compartment LN dissection is indicated when LNs are discovered on ultrasound or perioperatively. Palpable LNs are a predictive factor of recurrence. However, elective prophylactic LN dissection is controversial in the absence of preoperative suspicion of LN involvement. Although there is strong consensus to perform CND (centeral neck dissection) for therapeutic purposes, there is currently considerable controversy among surgeons regarding which patients should undergo prophylactic CND (centeral neck dissection) for differentiated thyroid cancer ,.
The controversies surrounding the performance of a prophylactic CND (centeral neck dissection) can be reflected in the varying recommendations from other national and international consensus groups. The National Comprehensive Cancer Network expert panel gives prophylactic CND (centeral neck dissection) a category 2B recommendation, stating that performance for patients with T3 or T4 tumors could be considered but must be weighed against the increased risk of hypoparathyroidism and nerve injury .
The European Society of Endocrine Surgeons states that prophylactic CND (centeral neck dissection) should be considered in those with high-risk features, including T3–T4 tumors, age less than 15 or more than 45, male sex, bilateral or multifocal disease, or known lateral neck LN metastases .
The Japanese Society of Thyroid Surgeons/Japanese Association of Endocrine Surgeons recommends routine performance of prophylactic CND (centeral neck dissection), based on increased risk of complications if surgery is needed for LN recurrence .
Their decision to perform a prophylactic CND in our study in patients with cN0 disease should be taken into account not only for T3 and T4 tumors but also for any tumor size with capsular or vascular invasion and if there is enlarged lower deep cervical LN.
Prophylactic CND and lateral neck dissection in their study of tumors less than 2 cm revealed LN metastases in 42% of all the patients and in 70% of patients with a tumor larger than 20 mm.
In our experience of this study, prophylactic CND and lateral neck dissection in tumors less than 2 cm revealed LN metastases in 23.3% of all the patients and in 53.6% of patients with a tumor larger than 20 mm.
LN dissection allows an accurate staging of the disease to determine postoperative treatment. In a recent consensus, postsurgical administration of 131I for T1 tumors (<2 cm) depends on LN status. Radioiodine 131I ablation is indicated for T1N1 and is not indicated for T1 less than 1 cm, unifocal, with N0, and is optional in case of T1Nx and mandatory in T2 or T3, N1. In our experience of this study, the results of CND and lateral neck dissection were used to decide to perform radioiodine (131I) ablation. Overall, 42% of patients were not treated with 131I because no LN metastases were found on pathological examination (except micrometastases). In 58% of cases, 131I ablation was performed for patients with LN metastases or for those presenting with other factors of poor prognosis (such as vascular invasion or unfavorable histology) .The central compartment LN metastasis represents the most common cause of recurrence. Prophylactic central ipsilateral neck dissection prophylactic central and for DTC less than 2 cm in diameter allowed selection of patients for 131I ablation and modified the indication for radioiodine in 30% of patients with pT1 tumors.
Therapeutic central LN dissection decreases the frequency of regional recurrences, and LN invasion appears to be an independent variable affecting the prognosis of T1–T2 tumors .
| Conclusion|| |
For patients with DTC, neck ultrasound is the most important imaging technique for preoperative assessment of non-palpable LN metastasis.
The role of prophylactic CLND for PTC for DTC continues to be controversial. With the available evidence, we advocate a selective approach to performing prophylactic CLND for PTC. Prophylactic central compartment neck dissection (ipsilateral or bilateral) should be considered in patients with DTC with clinically noninvolved central neck LNs (cN0) who have locally advanced primary tumors (T3 or T4), clinically involved lateral neck nodes (cN1b), or if the information will be used to plan further steps in therapy. For early-stage unifocal tumors (T1–T2), we advocate selective lymphadenectomy of the ipsilateral compartments because we found bilateral nodal metastasis only in more advanced or multifocal diseases.
Prophylactic CND and ipsilateral lateral neck dissection for DTC less than 2 cm in diameter allowed selection of patients for 131I ablation and modified the indication for radioiodine in 30% of patients with pT1 tumors.
Finally, the primary tumor T1 with central node metastasis N1 (pT1 and N1) is usually subjected to radioiodine treatment, whereas larger tumors such as pT2 without nodal involvement can avoid treatment.
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Conflicts of interest
There are no conflcits of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4]