53 Neck Dissection
A primary carcinoma arising from the upper aerodigestive tract may ultimately drain into the lymph nodes of the neck, which forms an efficient barrier to the further spread of the disease. The prognosis for the patient regardless of the site of the primary tumour is worse if there are cervical lymph nodes involved at presentation. Only 50% of such patients will survive longer than 5 years.
Treatment of cervical lymph nodes is either elective (in the clinically negative neck) or therapeutic (in the clinically positive neck). The modality chosen is usually the same as that used for the primary tumour. The surgical treatment of malignant neck nodes is by some form of neck dissection (ND). Broadly speaking, radiotherapy alone (RT) will only be effective in the curative treatment of cervical lymph node metastases if they are less than 2 cm in diameter. Concomitant chemotherapy (CR) is now advocated in advanced nodal disease, with the advantage that it precludes the need and morbidity of surgery, which can be kept in reserve for the treatment of any recurrence.
The choice of treatment modality and when it should be used can be controversial. It is a subject of debate in many multidisciplinary team (MDT) meetings. The discussion regarding elective (prophylactic) therapy in the N0 neck is now supplemented, in oral cavity cancer, by the increasing role of sentinel node biopsy. Furthermore, in cases treated by neck dissection as primary modality, there may be a requirement for adjuvant treatment. The rupture of the lymph node capsule by tumour (extracapsular spread [ECS]) is a bad prognostic sign. Fifty percent of nodes with a diameter greater than 3 cm exhibit this. Post-operative RT or CR to the neck following neck dissection is indicated in the presence of ECS and positive surgical margins.
The classification suggested by the American Academy’s Committee for Head and Neck Surgery and Oncology is still used, but there is an increasing trend to divide neck dissections into two broad types with subdivisions: comprehensive (removal of levels I–V) and selective (less than five levels). The need for less extensive surgery in the chemoradiation era has led to calls for revision of the system. Radical neck dissection is the standard basic procedure, and all others represent one or more alterations to this procedure. Modified radical neck dissection involves the preservation of one or more non-lymphatic structures routinely removed in radical neck dissection. Selective neck dissection (SND) involves the preservation of one or more lymph node groups routinely removed in radical neck dissection. Extended radical neck dissection involves removal of additional lymph node groups or non-lymphatic structures relative to the radical neck dissection (i.e., a superior mediastinal dissection in patients with subglottic or cervical oesophageal tumours).
1. Radical neck dissection.
2. Modified radical neck dissection.
3. Selective neck dissection.
(a) Supraomohyoid neck dissection. (b) Posterolateral neck dissection. (c) Lateral neck dissection. (d) Anterior compartment neck dissection.
4. Extended radical neck dissection.
53.1.1 Radical Neck Dissection
This operation refers to the removal of lymph nodes in the anterior and posterior triangles extending from the inferior border of the mandible superiorly to the clavicle inferiorly, the midline anteriorly and the anterior border of the trapezius muscle posteriorly. The cervical lymph node groups routinely removed are as follows: submental and submandibular; upper, middle and lower jugular (deep cervical); and the posterior triangle group. The submandibular gland, spinal accessory nerve, internal jugular vein and sternocleidomastoid muscle are also removed. Extended radical neck dissection consists of removal of all the structures in a radical neck dissection along with one or more additional lymph node groups (e.g., retropharyngeal nodes, parotid nodes, levels VI/VII) or non-lymphatic structures (e.g., parotid gland, hypoglossal nerve, digastric muscle, external carotid artery or skin) or both.
53.1.2 Modified Radical Neck Dissection
Modified radical neck dissection (MRND) consists of a monobloc removal of the cervical lymph nodes from levels I through V as with an RND. The procedure is modified by preservation of just the accessory nerve (Type I) or the accessory nerve and internal jugular vein (Type II), or the accessory nerve, internal jugular vein and sternocleidomastoid muscle (Type III), see Table 53.1.