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The Medical Bulletin of Sisli Etfal Hospital
The Standards And Definitions In Neck Dissections Of Differentiated Thyroid Cancer [SETB]
SETB. Ahead of Print: SETB-14227 | DOI: 10.14744/SEMB.2018.14227

The Standards And Definitions In Neck Dissections Of Differentiated Thyroid Cancer

Mehmet Uludağ1, Mert Tanal1, Adnan Işgör2
1Department of General Surgery, Istanbul Sisli Hamidiye Etfal Health Practice and Research Hospital, Health Sciences University, Istanbul, Turkey.
2Department of General Surgery, Bahcesehir University Faculty of Medicine, Istanbul, Turkey; Department of General Surgery, Sisli Memorial Hospital, Istanbul, Turkey.

Papillary and follicular thyroid carcinomas arising from follicular epithelial cells and forming differentiated thyroid cancer (DTC) consist more than 95% of thyroid cancers. Lymph node metastasis to the neck is common in DTC, especially in papillary thyroid cancer (PTC). The removal of only the metastatic lymph nodes (berry picking) does not help to achieve a potential positive contribution to the survival and recurrence by lymph node dissection in the DTC, thus systematic dissection of cervical lymph nodes is needed. Today, according to widely accepted and commonly used definitions and lymph node staging, deep lymph nodes of the lateral side of the neck is divided into 5 regions. Based on the fact that some groups have biologically independent regions, groups I, II and V are divided into A and B subgroups. Central region lymph nodes contain VI and VII. region lymph nodes, which consist of prelaryngeal, pretracheal, 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 Group I-V lymph nodes at one side, 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 radical neck dissection (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. Usually, involving one or more regions of SND is applied for DTC.
The removal of paratracheal, prelaryngeal, and pretracheal lymph node groups at one side is termed as ipsilateral central dissection, while removal of 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 (BCD). To summarize, bilateral 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 done 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 done 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-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 the prognosis and recurrence.

Keywords: thyroid; cancer; differentiated; cervical; lymphatic; dissection

The Standards And Definitions In Neck Dissections Of Differentiated Thyroid Cancer

Mehmet Uludağ1, Mert Tanal1, Adnan Işgör2
1Department of General Surgery, Istanbul Sisli Hamidiye Etfal Health Practice and Research Hospital, Health Sciences University, Istanbul, Turkey.
2Department of General Surgery, Bahcesehir University Faculty of Medicine, Istanbul, Turkey; Department of General Surgery, Sisli Memorial Hospital, Istanbul, Turkey.

Papillary and follicular thyroid carcinomas arising from follicular epithelial cells and forming differentiated thyroid cancer (DTC) consist more than 95% of thyroid cancers. Lymph node metastasis to the neck is common in DTC, especially in papillary thyroid cancer (PTC). The removal of only the metastatic lymph nodes (berry picking) does not help to achieve a potential positive contribution to the survival and recurrence by lymph node dissection in the DTC, thus systematic dissection of cervical lymph nodes is needed. Today, according to widely accepted and commonly used definitions and lymph node staging, deep lymph nodes of the lateral side of the neck is divided into 5 regions. Based on the fact that some groups have biologically independent regions, groups I, II and V are divided into A and B subgroups. Central region lymph nodes contain VI and VII. region lymph nodes, which consist of prelaryngeal, pretracheal, 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 Group I-V lymph nodes at one side, 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 radical neck dissection (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. Usually, involving one or more regions of SND is applied for DTC.
The removal of paratracheal, prelaryngeal, and pretracheal lymph node groups at one side is termed as ipsilateral central dissection, while removal of 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 (BCD). To summarize, bilateral 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 done 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 done 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-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 the prognosis and recurrence.

Anahtar Kelimeler: thyroid; cancer; differentiated; cervical; lymphatic; dissection



Corresponding Author: Mert Tanal, Türkiye
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