Extent of Lateral Neck Dissection in Differentiated Thyroid Carcinoma
In the surgical part of this review (1), the classification of cervical lymphadenectomies is restricted to central and lateral neck dissections. However, it is rather accurate and relevant to further break down and refine the latter term, as the surgical morbidity associated with classic radical or modified radical neck dissections can be significantly reduced by offering standardized, functional and selective neck dissections instead.
Similarly to other head and neck cancers, the American Thyroid Association (ATA) recommends the classification of the American Head and Neck Society, to precisely identify neck levels from I to VII, with additional side designation (2). Of these, levels I to V are included in a comprehensive lateral neck dissection, while levels VI and VII make up a central neck dissection. In cases with lateral lymph node involvement, where the metastatic burden is limited to levels III and IV, a selective dissection of levels IIa, III, IV, and Vb is recommended (2).
Further, there is evidence that the lymph node ratio (LNR), defined as the number of positive lymph nodes (numerator) divided by the total number of removed lymph nodes (denominator), is an independent prognostic factor (3). This is why it is paramount to achieve oncologic completeness by removing all lymph nodes from the selectively targeted neck levels while leaving all non-lymphatic structures intact, as this result has prognostic implications. The denominator of LNR, also known as nodal yield, depends—among other factors—on the applied surgical technique (4).
Dr. med. Balazs B. Lörincz, Ph.D.
Prof. Dr. med. Rainald Knecht
Universitäts-Klinik für HNO-Heilkunde, Kopf-Hals-Chirurgie und Onkologie
Conflict of interest statement
The authors declare that no conflict of interest exists.
|1.||Paschke R, Lincke T, Müller SP, Kreissl MC, Dralle H, Fassnacht M: The treatment of well-differentiated thyroid carcinoma. Dtsch Arztebl Int 2015; 112: 452–8 VOLLTEXT|
|2.||Stack BC, Ferris RL, Goldenberg D, et al.: American Thyroid Association consensus review and statement regarding the anatomy, terminology, and rationale for lateral neck dissection in differentiated thyroid cancer. Thyroid 2012; 22: 501–8 CrossRef MEDLINE|
|3.||Vas Nunes JH, Clark JR, Gao K, et al.: Prognostic implications of lymph node yield and lymph node ratio in papillary thyroid carcinoma. Thyroid 2013; 23: 811–6 CrossRef MEDLINE|
|4.||Lorincz BB, Langwieder F, Mockelmann N, Sehner S, Knecht R: The impact of surgical technique on neck dissection nodal yield: making a difference. Eur Arch Otorhinolaryngol. 2015 Mar 18 [Epub ahead of print] CrossRef|