Neck, Cervical Metastases, Surgery

See the list below:

• 1906: Crile developed the en bloc cervical lymphadenectomy known as the RND. In his classic series, spinal accessory and hypoglossal nerves were preserved.

• 1945: Dargent and Papillon proposed the preservation of the spinal accessory nerve (SAN) in clinically node-negative necks.

• 1950: Martin popularized the RND without preserving the spinal accessory nerve.

• 1963: Suarez demonstrated, based on his necropsy studies, that a complete cervical lymphadenectomy could be accomplished while sparing the sternocleidomastoid (SCM) muscle, the internal jugular vein (IJV), and the SAN.

• 1967: Bocca and Pignataro popularized functional/conservative neck dissections.

• 1969-1981: Roy and Beahrs, Carenfelt, and Eliasson advocated the possibility of preservation of SAN in clinically node-positive necks as well.[4, 5, 6]

• 1972: Lindberg's classic study of carcinomas of various upper aerodigestive tracts indicated consistent patterns of lymphatic drainage.[7]

• 1986-1994: Byers, Medina, and Spiro reported their satisfactory results with selective neck dissection (SLD).[8, 9]

Management of a neck mass requires understanding of anatomic, pathologic, and oncologic characteristics of the tumor. Differential diagnoses of neck masses are vast and need careful consideration in all patients who present with a neck mass. Imaging is an important tool to identify cervical metastasis; however, it may not clearly identify metastatic disease in early cancers. The management of neck masses has undergone a paradoxical shift from radical neck dissections, which were performed for N0 neck masses in the early 1900s, to the present era, in which chemoradiotherapy is advocated for advanced neck disease. This change in management has been brought about by several factors, such as morbidity of the procedure, better understanding of the tumor biology, patterns of spread, and advances in radio therapy.

To bring uniformity to the nomenclature for various neck dissections, the classification adopted today is the one adopted by the subcommittee for neck dissection terminology and classification of the American Academy of Otolaryngology Head and Neck Surgery in 2002.[10] Cervical metastases, most of which originate in the aerodigestive tract, are strong prognostic factors in head and neck cancers.

Frequency

In the United States, the frequency of metastatic disease for the upper aerodigestive tract varies widely from 1-85%, depending on the site, size, and differentiation of the tumor. For example, larger tumors have a greater likelihood of cervical spread, and pharyngeal lesions metastasize more frequently than those in the larynx or oral cavity.

Ipsilateral metastatic disease occurs in approximately 50% of patients with carcinoma of the oral cavity, oropharynx, hypopharynx, or supraglottis. Bilateral and/or contralateral metastatic disease occurs in 2-35% of these patients.

Nasopharyngeal carcinoma manifests as a neck metastasis in approximately 50% of patients.

Metastatic neck disease in individuals with thyroid gland tumors occurs as follows: papillary (55%), medullary (50%), and follicular (25%).

Tumors localized in the oral cavity, oral mucosa, oropharynx, hypopharynx, and supraglottis have a higher frequency of metastasis compared to areas such as the superior gingiva, hard palate, and glottis.

Most cervical metastases are SCCAs that originate from primary sites in the aerodigestive tract. Other sources of cervical metastasis include neoplasms of the skin, salivary glands, thyroid, lung, kidney, prostate, gonads, stomach, and breast. In some individuals, no primary cancer can be detected. In this situation, the carcinoma is labeled a metastasis from unknown origin.

A study by Okabe et al indicated that in patients who undergo endoscopic surgery for superficial head and neck carcinoma, various preoperative and postoperative findings increase the likelihood for cervical lymph node metastases, including 0-IIa type tumors, as found macroscopically; type B2/B3 vessels, as seen using narrow-band imaging; tumors classified as T2 or higher; lymphatic invasion; positive surgical margins; and a tumor thickness of greater than 1000 μm.[11]

Within the aerodigestive tracts, various factors contribute to the risk of neck metastasis. Young patients with oral carcinoma have a higher risk of developing nodal metastasis than older patients. Risk of neck involvement by metastasis increases with an increase of tumor size. Carcinomas in anterior portions of the oral cavity are less likely to metastasize to the neck than carcinomas in posterior portions. Perineural and perivascular invasion are associated with a high risk of nodal metastasis. Poorly differentiated tumors are associated with a higher risk of neck metastasis than well-differentiated tumors. Patterns of lymphatic metastasis are as follows:

With oral, tongue, retromolar trigone, and tonsillar fossa subsites, the jugulodigastric, submandibular, and midjugular lymph node stations are involved.

With the floor of the mouth as the subsite, the submandibular and jugulodigastric lymph node stations are involved.

With the soft palate, base of the tongue, oropharynx, supraglottis, and hypopharynx subsites, the jugulodigastric, midjugular, and contralateral lymph node stations are involved.

With the nasopharynx as the subsite, lymph node stations of the widest nodal distribution are involved.

Contralateral metastasis is found in the supraglottis, the base of the tongue, and the posterior pharyngeal wall palate.

Bilateral metastasis is found in the nasopharynx, the base of the tongue, the soft palate, the floor of mouth, and the supraglottis.

The highest rate of occult cervical metastasis is found in the oral cavity, pyriform sinus, tonsil, supraglottis, and pharyngeal wall.

Multiple cervical metastases (adenocarcinoma) occur with thyroid carcinoma, breast carcinoma, and nasopharyngeal carcinoma.

Involvement of particular groups of neck nodes includes the following:

• Posterior cervical nodes in nasopharyngeal and tonsillar carcinoma

• Tracheoesophageal nodes in thyroid, pyriform sinus, and subglottic carcinoma

• Periparotid and parotid nodes in SCCA of the skin of the temporal region and the cheek

A detailed understanding of the pathophysiology is mandatory step in the management of neck metastasis.

The intrinsic behavior of any malignant tumor in the body is to grow, invade, and metastasize. Head and neck SCCs predominantly metastasize via lymphatic channels to the lymph nodes as tumor emboli. In addition, they also spread through a venolymphatic pathway. The metastatic process largely depends on various tumor factors, such as expression of adhesion molecules like CD44 by the tumor cells or host immune factors.

Advances in molecular biology have given a better insight into the mechanisms involved in head and neck cancer.

Multiple gene products are involved in angiogenesis, all of which are critical for regulating the angiogenic phenotype. This has raised the need for comprehensive analysis of the angiogenic phenotype using microarray analysis and global proteomic approaches.[2] A complex interplay between positive and negative regulators determines the degree of neovascularization in and around the tumor.

Various markers assessing the role of regulators have been studied.

Matrix metalloproteinases (MMP) have the ability to degrade connective tissue such as the basement membrane, which is a crucial step in the initiation of metastatic process. Thus it serves as a negative regulator of metastasis. Similarly, E-cadherin is an important molecule that promotes cell-to-cell adhesion and serves as a positive regulator of metastasis. A study by Weiss et al indicated that angiogenesis and MMP and E-cadherin (M/E) ratio were specific predictors for metastases of renal cell carcinoma, especially to the lung or lymph node.[12] Therefore, MMP and E-cadherin are considered relevant targets for novel therapeutic strategies to control or prevent the metastasis of renal cell carcinoma. These results support exploring the role of angiogenetic regulators in head and neck cancer.

Expression levels of molecules involved in tissue remodeling and cell–extra cellular matrix (ECM) adhesion, especially MMP-1 and integrin-3 , can provide an accurate biomarker system for predicting the risk of cervical lymph node metastasis in oral SCC.[13] Low expression of E-cadherin should be considered a high risk for late cervical metastasis when a wait-and-see policy for the neck is adopted.[14]

Vascular endothelial growth factor (VEGF) promotes angiogenesis in many different tumor types. VEGF is a highly potent angiogenic agent that acts to increase vessel permeability and enhance endothelial cell growth, proliferation, migration, and differentiation.[15] VEGF levels may affect tumor growth, metastatic potential, and response to radiotherapy. VEGF positivity was the most significant predictor of poor prognosis. VEGF status may prove to be an important prognostic factor in head and neck cancer. In addition, the potent role of VEGF in angiogenesis has spurred interest in using this molecule as a therapeutic target in antiangiogenetic therapy.

History

Most of the probable primary carcinomas can be elicited in the history taking. Probable primary carcinoma sites and symptoms are as follows:

• Oral - Bleeding or painful ulcer in the mouth

• Nasopharynx - Nasal fullness, epistaxis, change in voice resonance, sinusitis

• Maxillary - Patch of anesthesia over cheek, toothache, epistaxis, sinusitis, change in the visual field

• Larynx, hypopharynx - Change in voice, cough, dysphagia, referred otalgia, hemoptysis, airway obstruction

• Tongue, base of tongue - Painful lesion, oral bleeding, odynophagia, ankyloglossia

• Esophageal - Dysphagia, weight loss, hoarseness, regurgitation

• Stomach - Dyspepsia, vomiting, epigastric pain

• Pancreatic head - Jaundice, epigastric pain, white stools

• Testicular - Painless testicular enlargement

• Lung - Cough, hemoptysis

• Breast - Breast lump

• Thyroid - Neck swelling

Review of the medical history should include allergies to medications, hypertension, diabetes mellitus, cardiopulmonary disease, other chronic illnesses, previous surgeries, and radiation therapy. Reviewing the use of tobacco products (smoked and chewed), consumption of alcohol, and use of betel nuts is also important.

Physical examination

Clinical staging of cervical metastasis is accurate in 65% of cases. It understages in 28% and overstages in 8% of cases. Short neck, obesity, and prior radiotherapy reduce the physician's ability to detect metastasis.

Clinical examination of the neck mass is the most sensitive parameter for assessing the operability of a neck node metastasis. The physical examination includes assessment and documentation of site and size of node, contralaterality and bilaterality, mobility, and skin involvement. In addition, examine the oral cavity and mucous membranes of the pharynx. Careful examination of the thyroid gland is essential to assess the presence of a primary carcinoma. Perform an indirect laryngoscopic examination of the larynx and the hypopharynx. If a lesion is noted in the aerodigestive tract, an evaluation under anesthesia further documents the location and size of the lesion, and it allows for a biopsy.

• Periabdominal examination should be performed to look for primary carcinomas in the abdomen.

• Perirectal/perivaginal examination should be performed in persons in whom primary carcinoma is suspected in the gastrointestinal (GI) or genitourinary tract.

• Perform a breast examination in selected individuals.

• Auscultate the chest to detect a possible pulmonary primary carcinoma.

• Perform a testicular examination.

Radical neck dissection

Indications for a radical neck dissection (RND) are N2 or N3 cervical adenopathy with or without bulky disease in the upper jugular region, presence of multiple lymph nodes, and residual or recurrent disease after radiation therapy.

Modified radical neck dissection

Modified RND indications are N0 neck (especially if the primary tumor is in the larynx or hypopharynx) in SCCA or melanoma, N1 neck disease, and papillary and follicular carcinoma of the thyroid.

Selective neck dissection

SND indications include the following:

• Lateral neck dissection is indicated in a tumor of the larynx, oropharynx, and/or hypopharynx staged T2-4, N0-1, and/or T1 N1 node within level I-II.

• Supraomohyoid neck dissection is indicated in SCCA of the oral cavity staged T2-4, N0/Tx N1 within level I-II.

• Bilateral procedure is indicated in anterior tongue and base of tongue cancers as well as T3-T4 carcinomas of the supraglottis.

• Posterolateral neck dissection is indicated in melanoma, SCCA, or another skin tumor with metastatic potential from the occipital scalp.

• Anterior neck dissection is indicated for thyroid, subglottic larynx, trachea, and cervical esophagus cancers.

• Mediastinal dissection is indicated in thyroid cancers, stomal recurrence, and postcricoid and esophageal invasion.

Lymph nodes of the head are located in the occipital, posterior auricular (postauricular), anterior auricular (preauricular), parotid, facial, deep facial, and lingual regions.

Lymph nodes of the neck are located in the superficial cervical, anterior cervical, submental, submaxillary, deep cervical, retropharyngeal, jugular, superior, inferior, spinal accessory, and transverse cervical node regions.

The skin of the neck derives its blood supply from the descending branches of the facial occipital arteries and from ascending branches of the transverse cervical and suprascapular arteries; therefore, the incisions most likely to safeguard the blood supply to the skin flaps are superiorly based apronlike incisions.

The following division of the neck nodes into regions as described at Memorial Sloan-Kettering is accepted universally (see the image below):

See the list below:

• Level 1 contains the submental and submandibular nodes.

• Level 2 is the upper third of the jugular nodes medial to the SCM, and the inferior boundary is the plane of the hyoid bone (clinical) or the bifurcation of the carotid artery (surgical).

• Level 3 describes the middle jugular nodes and is bounded inferiorly by the plane of the cricoid cartilage (clinical) or the omohyoid (surgical).

• Level 4 is defined superiorly by the omohyoid muscle and inferiorly by the clavicle.

• Level 5 contains the posterior cervical triangle nodes.

• Level 6 includes the paratracheal and pretracheal nodes.

The platysma is a wide quadrangular sheetlike muscle extending obliquely from the upper chest to the lower face. The skin flap is raised in a plane deep to the platysma. If the disease involves the platysma or is close to it, the platysma may be left attached to the specimen and the skin flap raised superficial to it.

The SAN exits the jugular foramen (medial to the digastric and styloid muscles) and lies lateral and immediately posterior to the IJV. The nerve can also be medial to the IJV in 30% of the cases. It runs obliquely inferiorly and posteriorly to reach the SCM near the junction of its upper and middle thirds or within 1 cm of the Erb point (where the greater auricular nerve curves around the posterior border of the SCM).

The digastric muscle originates from the digastric ridge in the mastoid process. The marginal mandibular nerve (a branch of the facial nerve) is the only structure superficial to the posterior belly of the digastric muscle that must be identified and preserved. It lies superficial to the 11th nerve, IJV, ICA, hypoglossal nerve, and the branches of the external carotid artery (ECA). When raising the upper skin flap or while incising the deep cervical fascia, care must be taken to identify the marginal mandibular nerve. It is located 1 cm in front of or below the angle of the mandible, deep to the superficial layer of the deep cervical fascia that envelops the submandibular gland.

The omohyoid muscle has 2 bellies and is the anatomic landmark separating levels III and IV. The posterior belly lies superficial to the brachial plexus, phrenic nerve, and transverse cervical artery and vein. The anterior belly lies immediately superficial to the IJV.

The posterior boundary of neck dissection is the anterior border of the trapezius muscle. The levator scapula is commonly mistaken for the trapezius, placing the 11th nerve and the nerve to the levator at risk. Dissection must be kept superficial to the fascia of the levator muscle to preserve the cervical nerves.

The brachial plexus exits between the anterior and middle scalene muscles. It extends inferiorly deep to the clavicle, under the posterior belly of the omohyoid muscle. The transverse cervical artery and vein lie superficial to it.

The phrenic nerve lies superficial to the anterior scalene muscle and derives its cervical supply from C3-5. Cervical rootlets must be transected only anteriorly to their contribution to the phrenic nerve.

The thoracic duct is located in the lowermost part of the left neck and arises immediately posterior to the lower end of the jugular vein and anterior to the phrenic nerve and transverse cervical artery. Care must be taken to handle it gently during ligation to avoid avulsion or tearing of walls.

The hypoglossal nerve exits via the hypoglossal canal, passes over the ICA and ECA, under the IJV, and loops deep to the posterior belly of digastric, where it is enveloped by a ranine venous plexus. It then travels under the fascia of the submandibular triangle before entering the tongue.

The neck is divided into the anterior and the posterior triangle, each of which is divided into smaller triangles. The anterior triangle is divided into the submental triangle, submandibular triangle, superior carotid triangle, and inferior carotid triangle. The posterior triangle is subdivided into the occipital triangle and subclavian triangle.

Classification of lymph nodes

The submental node is located in the submental triangle and receives afferent flow from superficial lymphatics from the cheek, lower lip, and chin.

The submandibular node is located between the anterior and posterior bellies of digastric muscle and receives afferent flow from the lower lip, sublingual area, ipsilateral oral cavity, eyelid, cheek, and nasal mucosa.

The facial node is located superficial to the facial muscle and along the facial vein and receives afferent flow from facial skin, palate, and buccal mucosa.

The parotid node is located in the intraglandular or extraglandular part of the parotid, and it receives afferent flow from the scalp, auricle, external auditory canal (EAC), eardrum, and the eustachian tube (E-tube).

The retropharyngeal node is located posterior to the pharyngeal wall, between the prevertebral fascia and the pharyngeal wall, and it receives afferent flow from the posterior nasal cavity, palate, nasopharynx, and eustachian tube.

The anterior cervical node is located in the superficial anterior jugular chain, and pretracheal, prelaryngeal, and paratracheal regions, and it receives afferent flow from the larynx, upper trachea, and esophagus.

The spinal accessory node is located along the SAN and receives afferent flow from the occipital, mastoid, and maxillary sinus.

The supraclavicular node is located at the jugulosubclavian junction and receives afferent flow from the spinal accessory, lower neck, upper chest, lung, and GI tract.

The internal jugular node is located along the internal jugular chain and receives afferent flow from the superior nodal group, mucosal site in the head and neck, and thoracic and axillary nodes.

General contraindications to surgery include too great a surgical risk because of cardiopulmonary disease and cases in which the patient cannot be optimized preoperatively.

RND contraindications include the inability to control the primary tumor or distant metastasis, a fixed neck mass through the deep cervical fascia, a mass in the supraclavicular triangle, and the inability of the surgeon to completely remove all gross disease from the neck, including the skull base, vertebral fascia, carotid artery, deep muscle, phrenic nerve, and brachial plexus.

Contraindications for SND are N2 and N3 disease, recurrence or previous treatment with radiation therapy, involvement of spinal accessory chain, and melanoma of clinically positive nodes.

Workup is aimed at establishing the cytologic and histologic diagnosis of the neck mass, establishing the primary carcinoma, evaluating the extent of local (neck) disease, evaluating the extent of systemic spread, and assessing operative fitness (if operation is necessary).

CBC count and differential count provide a baseline hematologic status. Patients with carcinoma of the stomach, carcinoma of the colon, and advanced cancers of the head and neck may present with anemia.

A blood glucose test is useful to screen patients with diabetes mellitus.

Any alteration in the liver enzyme profile can be used to predict either coexisting liver primary disease (eg, cirrhosis, hepatitis) or a liver metastasis. Liver enzyme profiles are also important to determine anesthetic fitness.

BUN and creatinine levels are important to determine anesthetic fitness.

Prothrombin time (PT) and activated partial thromboplastin time (aPTT) are used to assess any possible bleeding diathesis preoperatively.

Electrolyte levels are important, especially in patients with advanced head and neck cancer who have been devoid of oral feeding for a long time.

Determine the patient's blood group.

Perform a urinalysis.

Chest radiography can reveal either a primary tumor in a lung or synchronous pulmonary metastasis. Excluding any other coexisting pulmonary pathology is important.

Esophagography (barium swallow) may be helpful in evaluating a hypopharyngeal, postcricoid, and/or esophageal primary tumor.

Ultrasonography is easy and reproducible and is an outpatient procedure. It is an inexpensive investigation, easy to use by a radiologist, and can be used bedside. Most radiologists are well trained in ultrasonography, and only a little more training is required for assessing the neck nodal status. Ultrasonographically guided aspiration cytology can be performed to determine the cause of cervical neck metastasis. It has a specificity nearing 100%. Doppler study can be performed to assess the status of neck vessels.

CT scanning and MRI can be used to reduce the risk of occult disease to 12%. MRI and CT scanning have demonstrated greater sensitivity in the detection of nodes smaller than 1-1.5 cm. CT scanning is the most commonly used investigation to evaluate and stage the disease.

CT scan criteria for assessing nodal metastases include increased size (>1.5 cm for jugulodigastric and submandibular nodes, >1.0 cm for all other cervical nodes, >0.8 cm for retropharyngeal nodes). Unfortunately, lymph node size does not always correlate with metastatic disease.

Other CT scan criteria for assessing nodal metastases are ill defined or irregular bordered mass, rounded shape, central necrosis, and nodal grouping (3 or more nodes in the range of 6-15 mm). The node periphery is usually thick and enhances with contrast. Obliteration of the fat line around the carotid sheath is a sign of sheath infiltration.

CT scanning is more precise than MRI in demonstrating tumor necrosis and extracapsular spread.

MRI tends to reveal retropharyngeal node involvement better than CT scanning does.

Contrast agents (eg, iron oxide) during MRI have demonstrated encouraging results of reduced signal intensity in normal nodes (compared to involved nodes) after contrast administration.

Several studies suggest that 18-F-fluorodeoxyglucose (FDG)-positron emission tomography (PET)/CT scanning is superior to CT scanning alone for neck node involvement. Confirmatory trials to substantiate the accuracy of FDG-PET/CT neck staging are still awaited. Patients who have achieved a complete response at the primary site but have a residual abnormality in the neck may benefit from PET/CT scanning because it is more sensitive and specific than CT scanning alone.

If tumor involvement of the carotid artery is possible, perform 4-vessel cerebral angiography to evaluate the status of the contralateral carotid, intracerebral circulation, and carotid back pressure; also, perform a balloon occlusion test.

Evaluate weight and nutritional status, especially in patients with head and neck cancer.

Perform electrocardiography.

With regard to sentinel node (SN) biopsy, few studies have validated the sentinel node hypothesis for oral and oropharyngeal cancer. The role of SN biopsy in the management of the N0 neck in such patients has yet to be established through prospective trials.

Fine-needle aspiration cytology, which is the first and probably most important procedure for further management, can be used to differentiate inflammatory, benign, and malignant pathologies and can provide cytologic distinction (eg, SCCA, adenocarcinoma, germ cell tumor, lymphoma).

Immunocytochemistry can further aid in locating a primary carcinoma.

The primary tumor can be located by palpation, or, in difficult cases, ultrasonographic guidance can be helpful.

Indirect laryngoscopy/fiberoptic nasopharyngolaryngoscopy is used to detect and evaluate a possible primary carcinoma in the head and neck.

Panendoscopy is used to exclude a second primary tumor or to detect the primary tumor if it is not easily detectable. This helps in obtaining a biopsy. The pyriform sinus, base of tongue, nasopharynx, and tonsils are some of the notorious areas of occult tumors, and these areas may require random biopsy if the primary carcinoma site is unknown.

A true-cut or an open biopsy is indicated when needle aspiration cytology findings are inconclusive.

Most patients (60-85%) with neck metastases have SCCA; second most common is adenocarcinoma (occurring in 13-22% of patients). Undifferentiated carcinomas and melanomas account for 10% of patients with neck metastases, and 8% of such patients have cervical metastasis. Very rarely, other occult malignant neoplasms, such as sarcomas and germ cell tumors, metastasize to the neck.

Fine-needle aspiration cytology or a biopsy of the neck mass helps in predicting the primary carcinoma site, such as SCCA from upper aerodigestive tract, nasopharyngeal carcinoma, thyroid carcinomas, skin cancer of the head and neck, and breast cancers.

Cervical metastases of the neck are staged as follows:

• NX: Regional lymph nodes cannot be assessed.

• N0: No regional lymph node metastasis is observed.

• N1: Metastasis is observed in a single ipsilateral lymph node, measuring 3 cm or less in greatest dimension.

• N2a: Metastasis in a single ipsilateral lymph node is observed and measures more than 3 cm but less than 6 cm in greatest dimension.

• N2b: Metastasis is found in multiple ipsilateral lymph nodes; none of the nodes measure greater than 6 cm in their greatest dimension.

• N2c: Metastasis in bilateral or contralateral nodes is observed; no nodes are larger than 6 cm in their greatest dimension.

• N3: Metastasis is observed in a lymph node that measures greater than 6 cm in its greatest dimension.

In the N0 neck, no prospective studies demonstrate survival rate differences among patients who undergo surgical, radiation, and expectant management. In view of poor prognosis at the time of future relapse, persons with primary lesions with more than 20% likelihood of metastasis should undergo either surgery or radiation therapy at the time of primary treatment. Radiation therapy in the N0 neck reduces the recurrence rate to approximately 5%. The node-positive neck is more effectively treated with a combination of surgery and radiation. In patients with bulky nodal disease, a complete response in the neck to sequential chemotherapy and radiotherapy or radiotherapy alone may indicate that neck surgery is not necessary for good locoregional control and improved disease-free survival rates.[16]

Comprehensive neck dissections include RND and its 3 modifications (ie, MND, SND, and END).

Radical neck dissection

RND involves the removal of all lymphatics from the inferior border of the mandible to the clavicle between the lateral border of the strap muscles and the anterior border of the trapezius (removal of all soft tissue in levels I-V). The floor of resection is formed by the fascial plane of the scalene muscles and the levator scapulae. The SCM, the IJV, and the SAN are removed. Traditionally, RND was the only surgical method of treating the neck; however, with the encouraging results of the more limited modifications resulting in less morbidity, RND is no longer indicated in most cases, even in node-positive necks.

Modified radical neck dissection (Medina classification)

MND is based on the concepts that (1) an en bloc removal of the cervical lymphatics can be accomplished by stripping the fascia from the SCM and IJV, (2) no lymphatic communication was ever noted between these structures and the cervical lymphatics, (3) both the spinal accessory and the hypoglossal nerves do not follow the aponeurotic compartments but rather run across them; therefore, if the tumor does not directly involve the nerves, they can be spared and (4) shoulder dysfunction can be avoided.

Type I modified radical neck dissection: The procedure for the type I modified RND is the same as the RND except that the SAN is spared. This technique is used less commonly in the N0 neck, but it would be a reasonable choice with neck disease that involved the SCM or jugular vein without involving the SAN. The survival rate and the disease-free survival rate are not affected by preservation of the SAN. The pattern of failure is the same for the 2 procedures (ie, nerve preservation does not cause higher chances of recurrence).

Type II modified radical neck dissection: This surgery is the same as in the RND, but the SAN and IJV are spared. The type II modified RND is indicated in node-positive necks with metastatic involvement of the SCM but without involvement of the nerve and vein.

Type III modified radical neck dissection (functional neck dissection): Type III modified RND is similar to the RND with preservation of all 3 structures (ie, SAN, IJV, SCM). In many centers, this operation is popular in the treatment of hypopharyngeal and laryngeal tumors with N0 necks. Molinari, Lingeman, and Gavilan propose this procedure for N1 necks when the involved nodes are mobile and do not measure more than 2.5-3 cm. Bocca proposes this operation for any neck that has indications for an RND as long as the nodes are not fixed.[2] The recurrence rates with functional neck dissection are similar to those associated with RND. See the image below.

Selective neck dissections

SNDs are based on recent understandings of lymphatic spread in the head and neck.[17] Only those regions with high risk for metastasis are removed.[18, 8] The SND provides the same survival rate and/or disease-free survival rate and staging information as RND. Manipulation of the SAN is minimized in SNDs, although short-term (3-4 mo) reversible shoulder dysfunction can occur.[19]

Types of selective neck dissection are as follows:

• Supraomohyoid (anterolateral) neck dissection: levels I, II, and III are removed and the SCM, IJV, and SAN are spared. This dissection is indicated in the treatment of oral cavity lesions.

• Lateral neck dissection: levels II, III, and IV are removed, sparing the SCM, IJ, and SAN. Lateral neck dissection is indicated in tumors of the larynx, oropharynx, and hypopharynx in a node-negative neck.

• Posterolateral neck dissection: levels II, III, IV, and V are removed, sparing the SCM, IJV, and SAN. Posterolateral neck dissection is indicated in the treatment of skin tumors located in the posterior scalp or neck (eg, melanomas, SCCA, Merkel cell carcinomas).

Extended neck dissections

Any of the above dissections that encompass the removal of additional structures or other groups of lymph nodes are extended neck dissections. Retropharyngeal node involvement often occurs in tumors of the pharyngeal walls. level VI excision is required in thyroid, tracheal, and postcricoid carcinomas. Tumor infiltration into the carotid artery, hypoglossal nerve, and levator scapulae muscles may warrant excision. Paratracheal and pretracheal nodes, vertebral transverse process, and mediastinal nodes removal may be necessary in some situations.

Management of the neck in cancer of the hypopharynx

Cancer of the hypopharynx is a distinct disease amongst other cancers of head and neck. The rate of lymph node metastasis in region I, II, III, IV, and V is around 3.57%, 62.02%, 37.17%, 42.17%, and 8.62%, respectively.[20] The rate of occult metastasis in cancer of the hypopharynx is around 20%. In cases of N0 and N+ neck, SND II-IV and SND II-V is required, respectively. Contralateral neck dissection is required in cases of involvement of posterior pharyngeal wall, postcricoid, medial wall of pyriform, stage IV disease, and palpable ipsilateral nodes.[21]

Management of the neck in cancer of the thyroid

Amongst the cases of cancer of the thyroid, the most common variety is papillary. Cervical nodes are involved in 30-80% of the cases. Management of central compartment nodes in N0 disease is still controversial. In N+ disease, the involvement of ipsilateral neck nodes is 75%, 69.4%, 56.9%, and 20.8% for levels IV, III, II, and V, respectively; the central compartment is positive in 87.5% of ipsilateral and 26.4% of contralateral cases. In N+ necks, occult metastasis occurs on ipsilateral side in 42.2%, 47.3%, 64.5%, and 26.3% in level II, III, IV, V, respectively.

The rate of skip metastasis (ie, involvement of lateral compartment without involved central compartment) is 11%. In the central compartment, the rate of occult metastasis is 77.8% on the ipsilateral side and 27% on the contralateral side.

level I dissection is not performed routinely unless it is involved.[22] SND level II-V with B/L central compartment clearance is performed in all N+ cases. level IIb is dissected if level IIa nodes are involved, and level Va nodes are never dissected. Berry-picking is never recommended.[23, 24]

In cases of N0 neck cancer, the rate of occult metastasis is 23%—19% in central the compartment and 8% in the lateral compartment.[25] In cases of low-risk N0 disease, dissection should involve II-IV and the ipsilateral central compartment, with possible sparing of level V.[26, 24]

Prophylactic central compartment dissection should be performed in T3/4, tumors larger than 4 cm, extrathyroidal extension, and preoperative BRAF mutation–positive cases.[27]

level VII should be removed with level VI as part of the central compartment as it is positive in 38% of N+ cases and 16% of N0 cases.[28]

In cases of medullary cancer of the thyroid, central compartment clearance is the minimum procedure required, with SND level II-V if lateral neck node metastasis is found.[29]

Management of the neck in cancer of the maxilla

There is controversy with regard to the management of neck in SCC of the maxilla, and, in cases of N0 necks, it is generally less aggressive compared with SCC of the oral cavity. The risk of regional metastasis with SCCA of the maxilla and tumors of the oral cavity is 37% and 40%, respectively.[30]

In all cases of N0 neck cancer combined (T1-T4), there is no effect with SND on 5-year overall survival compared with no SND (88% vs 86%) and on the regional recurrence rate (17% vs 18%). The benefit of SND is seen in locally advanced T4 disease, with increased 5-year overall survival of 81%, compared with 56% without SND. This warrants a need for neck dissection in locally advanced tumors with an N0 neck.[31]

In case of tumors with an N+ neck, management is resection of the primary tumor and selective neck dissection (I-IV/V) with postoperative radiotherapy. Selective neck dissection is also required in all cases in which reconstruction is by a free flap.[32]

Management of the neck in cancer of the parotid

Parotid tumors are quite uncommon, with the rate of malignancy being 14-25% and the rest benign. The rate of occult metastasis in N0 cancer of the parotid is 20-50%, mainly to level II-IV. The rate of clinically enlarged lymph nodes in high- and low-grade tumors is 36% and 15%, respectively.

Routine level II and III elective neck dissection is required in all cases of N0 neck cancer.[33] The neck can be observed in cases of low-grade mucoepidermoid carcinoma with radiologically confirmed N0 disease.[34] Neck dissection has to be performed in every case of high-grade malignancy or advanced disease with N0 neck disease.[35] In N+ neck disease, modified radical neck dissection is required, along with parotidectomy.[36]

Perform a complete physical examination (especially head and neck), including evaluation of the patient's ability to open the mouth adequately for intubation, evaluation of the airway and dentition of the patient, and assessment of cardiopulmonary status.

Obtain medical clearance and recommendations. Instruct the patient to take regular medications until the midnight before the surgical procedure. Ensure that informed consent has been fully discussed with the patient. Explain the disease, treatment plan, possible complications, and alternative plans to the patient and relatives.

Order nothing by mouth (NPO) after midnight on the night before surgery is planned. Note order of premedication and preoperative antibiotics.

Airway

Performing a tracheotomy under local anesthesia is better if a difficult intubation is anticipated. For surgery within the oral cavity or through the oral cavity, nasal intubation is required. For nonoral surgeries or approaches, orotracheal intubation is preferred. Packing around the tube may prevent aspiration and leakage. In difficult cases, bronchoscope-assisted intubation is recommended.

If the surgery is prolonged or complex, insert a urologic catheter for better control of urine output.

Positioning

Place the patient in a supine position with a shoulder roll extending the neck. Pull the arm gently down and strap it to the side of body. Elevate the head end by approximately 30°. Rotate the head to the opposite side and push the chin upward to obtain maximum extension. Prepare and drape the patient's neck and upper chest in a sterile fashion for the surgery.

Incisions

Various incisions are available (eg, Crile, Hayes Martin, MacFee, hockey-stick). The incision used depends on the location of the primary tumor and whether surgery is planned for 1 or both sides of the neck. In making the incision, the surgeon should avoid trifurcation over the region of the carotid artery and narrow-based flaps. If an RND is to be performed alone, the hockey-stick incision is generally preferred. Mark the skin incision. Infiltration of the skin incision with 10 mL of lidocaine with 1:100,000 epinephrine minimizes bleeding. Make scratch marks with the back of the knife to assist in the alignment of the skin flaps at the end of the operation.

Flap raising

Make the skin incision through the platysma and elevate the flap in the subplatysmal plane. Traction with the surgeon's fingers and countertraction by the assistant with skin hooks are definitely required. Leave the greater auricular nerve and external jugular vein on the SCM while raising the superior lateral aspect of the flap. Elevate the posterior flap toward the trapezius muscle. Identify and preserve the marginal mandibular nerve at the superior aspect of the flap. This nerve passes within the fascia of the submandibular gland. A simple way to protect this nerve is to divide the common facial vein at the anterior border of the SCM muscle and to dissect the superior flap deep to this vein.

Dissection

Remove submental fatty tissue and displace it inferiorly. Retract the mylohyoid muscle to expose the lingual nerve, and submandibular duct. Ligate and cut the facial artery, submandibular duct, and mylohyoid vessels. Remove the submandibular nodes and the submandibular gland and sweep them down. Cut the SCM superiorly 1 cm from the mastoid to expose the posterior belly of the digastric muscle. Expose the SCM and incise it just above the clavicle. Identify the anterior and posterior belly of the omohyoid and transect. Identify the IJV, carotid, and vagus nerve in the lower aspect of the neck. Ligate IJV in case of classic radical dissection or type 1 modified dissection.

Open the supraclavicular fatty tissue and identify the phrenic nerve and brachial plexus. Preserve the phrenic nerve and brachial plexus. Once the brachial plexus is visualized, clamp the fibrofatty tissue with a large clamp. The SAN is sacrificed in the RND, but in an MND, the nerve has to be traced while raising the lateral skin flap and while dissecting laterally. Continue the dissection along the anterior border of the trapezius. Follow the cervical branches and section them high on the specimen. Separate the specimen from the carotid, vagus, and hypoglossal while proceeding superiorly. Preserve the superior thyroid artery and superior laryngeal nerve. Identify the IJV superiorly and ligate. Achieve good hemostasis and insert vacuum drains, 2 for each side of the neck. Close the wounds in layers (ie, platysma followed by skin).

A liquid or light diet is allowable a few hours after surgery if none of the structures allowing the patient to protect his or her airway or allowing deglutition has been violated. An appropriately longer period may be needed if the neck dissection is combined with more extensive surgical procedures (eg, 7-8 days NPO if pharynx has been opened and flap inserted).

Maintain head elevation at a 30° angle. Monitor vital signs and intake and output every 4 hours. Watch for bleeding or hematoma formation. Watch for fistula formation if the thoracic duct was damaged intraoperatively or the pharynx was opened accidentally. Maintain constant humidification, suctioning, and cleansing of the tracheotomy tube. Make sure that the Hemovac or suction drains are functioning properly and the drains do not clot. Administer antibiotics per hospital protocol and pain medications as needed. Encourage early ambulation with assistance and deep breathing exercises.

Discharge criteria

Discharge is appropriate once the suction and drains have been removed (usually fourth to fifth postoperative day) and the wound has healed satisfactorily. No evidence of bleeding or infection should be present. An adequate airway and nutrition must be established. Adequate family and/or home care support are also necessary.

Physical therapy for the shoulder is initiated prior to discharge and continued at home. Review the patient's status after 7 days.

Check the pathology report for complete or incomplete resection and carcinoma-free margins and plan adjuvant treatment (ie, radiation therapy and/or chemotherapy). Remove sutures or clips at day 7, except when radiation therapy has been administered.

Long-term follow-up care should include monitoring for a recurrent tumor or development of a second primary. The patient should be seen every month for the first year. Continue follow-up every 2-4 months for up to 5 years. After this interval, the patient may be seen yearly.

For excellent patient education resources, visit eMedicineHealth's Cancer Center. Also, see eMedicineHealth's patient education article Cancer of the Mouth and Throat.

Neck dissections are safe operations with remarkably low mortality and morbidity.

The advantages of MND are preservation of neck and shoulder function, improved cosmesis, and protection of the ICA; also, the procedure may potentially be performed bilaterally simultaneously.[2] MND offers the same survival and disease-free survival benefits as classic RND.

Factors predisposing to complications include the following:

• Composite resection of mucosal areas

• Previous radiation therapy

• Advanced age

• Poor general health

• Systemic illness

• Chronic malnutrition

• Smoking

• Alcoholism

• Diabetes mellitus

Intraoperative complications

See the list below:

• Hemorrhage: Hemorrhage is an uncommon complication if careful attention is paid to anatomy and hemostasis with the electrocautery unit. Injury to the carotid during surgery should be repaired immediately. If excessive bleeding occurs from the lower end of the jugular vein, apply pressure followed by adequate suctioning until the stump is visualized and ligate properly. If the bleeding occurs from the upper end of the vein and the stump is not visualized, then packing the jugular foramen with large pieces of Surgicel and/or plicating with the posterior belly of the digastric muscle controls the bleeding.

• Hypotension: Hypotension occurs when dissecting around the carotid bifurcation (carotid sinus reflux). This may be avoided with careful dissection at the carotid bifurcation without manipulation. Local spray or injection of 2 mL of local anesthetic into the adventitia at the carotid bifurcation may help.

• Pneumothorax: Pneumothorax is a very rare complication when dissection involves paratracheal nodes and base of the neck areas. It involves a sudden compromise of the respiratory and circulatory system. If the pneumothorax is small, airtight closure of the wound usually controls the situation. A large pleural leak requires immediate placement of a chest tube with an underwater drainage.

• Air embolus: An air embolus can occur when a large vein is inadvertently opened and a large volume of air enters rapidly into the open vein by negative pressure and passes directly into the right atrium. Clinically, hypotension and cyanosis suddenly appear, the peripheral pulse disappears, and a loud churning noise is heard over the precordial area. The treatment involves immediate clamping of the offending vein and turning the patient onto the left side with the head down. Prevention is best, with careful identification, adequate ligations, and transfixion sutures.

• Nerve damage: With nerve damage, a loss of sensation occurs in multiple areas, including the neck, posterior occiput, external ear, mandibular region, lateral shoulder, deltoid area, and upper pectoral area. The marginal mandibular nerve is preserved unless it is involved by metastatic disease. Its damage results in lower lip weakness. The sacrifice of the cervical sympathetic chain produces Horner syndrome. The removal and/or damage of the SAN produces shoulder drop, limitation in the range of motion of the arm and shoulder, and pain in the affected areas. Most patients improve markedly with physical therapy. Unilateral resection of the hypoglossal nerve is usually well tolerated, but bilateral hypoglossal nerve resection causes severe difficulty in feeding, swallowing, and speaking. Resection or injury to the lower or middle neck of the vagus nerve causes vocal cord paralysis. Injury to the brachial plexus is a complication that should be avoided by proper identification of anatomic planes.

• Thoracic duct injury: Thoracic duct injury can occur with dissection of the region of the thoracic duct, particularly on the left side. If it occurs, ligate the thoracic duct. Ask the anesthesiologist to apply positive pressure to reevaluate whether leaking is present. If leak persists, then apply more sutures.

Postoperative complications

Patients who have received radiation therapy prior to RND are prone to have increased postoperative complications (eg, wound infection, fistula, flap necrosis, osteoradionecrosis, carotid artery rupture). Few institutions reserve surgery for salvage after unsuccessful radiotherapy in the treatment of cancer of the head and neck.

• Hematoma: Meticulous hemostasis and the use of suction drains are the best ways to avoid a hematoma. A hematoma is evident by accumulation of blood under the flap in the first few hours after the operation. Reexploration, evacuation of the hematoma, ligation of the offending vessel, irrigation, replacement of drains, and resuturing are essential.

• Wound infection: While a wound infection is very unlikely when RND is performed alone, it usually occurs in association with en bloc mucosal resection. Other predisposing factors to wound infection are previous irradiation, ischemia, malnutrition, chemotherapy, anemia, diabetes mellitus, and advanced tumor mass. Prompt debridement and infection control measures are required.

• Skin flap loss: Skin flap loss is a consequence of poor vascularity, errors in design or elevation, underlying hematoma, preexisting scars, infection, and poor nutrition. If the carotid artery is not exposed, then a conservative approach in the form of careful trimming of necrotic tissue and regular wound dressings is sufficient. If the carotid artery is exposed, then coverage is needed. The flaps used include the deltopectoral, pectoralis major, and trapezius.

• Salivary fistula: Salivary fistula occurs when the oral cavity and pharynx have been opened. The fistula appears within 4-5 days of surgery. It may appear as a small leak and is usually managed with conservative measures.

• Chylous fistula: A chylous fistula appears within 24-48 hours and can be identified by the appearance of a milky fluid in the drains. If it is minimal, it can be controlled by aspiration, pressure dressings, and a fat-free diet. When the leak is extensive (>500 mL of drainage), ligation of the offending thoracic duct is required.

• Facial edema: Facial edema is more commonly observed in patients with previous irradiation. Ipsilateral involvement occurs with unilateral neck dissection (especially with removal of the IJV). Facial edema reaches a maximum at postoperative days 5 and 6, followed by a progressive decrease in a few weeks. Bilateral resection of IJVs at the same time results in massive facial edema. Airway management with a tracheotomy may be required. With cerebral edema, the increase of intracranial pressure can cause neurologic deficit and even coma.

• Electrolyte disturbances: Hyponatremia is the most common postoperative electrolyte disturbance. It is usually dilutional or, in some individuals, is due to inappropriate secretion of antidiuretic hormone. It is manifested by altered behavior, restlessness, and hallucinations.

• Carotid artery rupture: The frequency of this complication ranges from 3-7%. It is observed in patients who have undergone RND with resection of mucosal areas. Prior radiation therapy, infection, flap necrosis, and salivary fistula are some of the predisposing factors. Apply direct and firm pressure and, if the bleeding cannot be controlled by pressure, clamp the common carotid artery as an emergency procedure and avoid repair or diversion in an area of infection. If a salivary fistula is present, attempts should be made to divert it. Cover the carotid artery with the levator scapulae or posterior scalene muscle.

Cervical metastasis is the single most important prognosticator in head and neck SCCA, and its presence indicates a roughly 50% reduction in the overall survival rate. The prevalence of lymphatic spread is greater than 20% for most of the SCCAs of the head and neck. A neck with histologically negative findings has a recurrence rate of 3-7%, and in contrast, a neck with histologically positive findings has a recurrence rate of 20-70%. Prognostic factors of cervical metastasis are site, size and number of metastatic nodes, and extracapsular spread.

Those patients with involvement beyond the first echelon of lymphatic drainage have a poorer prognosis (eg, a very low survival rate is observed if level V is involved in nonnasopharyngeal tumors). Posterior triangle and contralateral involvement are also indications of a poor prognosis.

The number of involved nodes significantly impacts the survival rate, with involvement of 2 or more nodes carrying a much higher frequency of distant metastasis and local recurrence. Involvement of several nodes (4 or more) is associated with a worse prognosis than involvement of only one node. Multiple levels of involvement are associated with a recurrence rate of 70%; only 1 level of involvement has a recurrence rate of 35%. A correlation exists between size and perineural and perivascular infiltration of the tumor.

A study by Sheppard et al indicated that in patients who undergo modified RND in head and neck SCCA, a lymph node ratio of 6.5% or greater independently predicts reduced overall survival, disease-free survival, and distant metastasis–free survival. The same was not found to be true for individuals who undergo selective neck dissection (I-III).[37]

Extracapsular spread is commonly found in 25% of small nodes and 75% of large nodes. It decreases the survival rate and the disease-free interval by one half. Macroscopic extracapsular spread has a recurrence rate of 45%, and microscopic spread has a recurrence rate of 25%.

Perineural and perivascular invasions are associated with more aggressive tumor behavior. Involvement of the tumor margins carries a poor prognosis and a high risk for recurrent neck disease. Node fixation, especially to the carotid artery or a muscle, is an ominous sign. Fixation occurs with large masses and denotes a poor prognosis. Degree of differentiation is a prognostic factor of cervical metastasis; poorly differentiated tumors are more aggressive and carry a poor prognosis. Lymphoid cell reaction and recurrent disease are other prognostic factors.

Sentinel node biopsy

Sentinel node biopsy was introduced in 1977 by Cabanas and has been worked upon since 1990, primarily in breast cancers and melanoma.[38] Sentinel lymph node biopsy has not yet gained popularity in oral and oropharyngeal cancers. In recent years, however, a few multicenter trials and meta-analyses have reported positive results. These have encouraged many centers around the world to further research this aspect.

According to the sentinel node biopsy philosophy, if the first draining node of a primary has micrometastasis, the rest of the nodes are very likely to be affected. This is irrespective of lymphatic drainage of the site, however unconventional it may be. The procedure involves lymphoscintigraphy after the injection of radiocolloids, prior to the surgery. During surgery, a patent blue dye is injected to visually mark the node. Thereafter, an incision of the biopsy is taken and the node is traced by a gamma probe. This gamma probe is fitted with a collimator to exclude radiation from everywhere accept a small area. The identified node is dissected and sent for histopathogical examination and immunohistochemistry. If the sentinel node is found to be positive, a neck dissection is performed.

A multicenter trial (Ross et al) conducted from 1998 to 2002 reported sentinel node procedures in 227 patients of head and neck carcinoma.[12] Of these 227 patients, 134 patients had T1/T2 lesions of the oral cavity and oropharynx. The sensitivity in these 134 patients was 93%. The study concluded that sentinel node biopsy can be used alone as a staging tool for oral and oropharyngeal squamous carcinomas.[39] Some authors have reported 100% sensitivity.[13] Hart et al reported 100% negative predictive value for SNB.[14] However, the study involved only 20 patients. Paleri et al conducted a meta-analysis of sentinel node biopsy reports on 301 patients of the oral cavity and 46 patients of the oropharynx.[15] This meta-analysis showed that the cumulative pay off for sentinel node biopsy alone as a staging procedure was 1% less than those with elective neck dissection in terms of recurrence and mortality rates. Identification rates with radiotracer dye was 97%.

Choice of colloid

Two colloids are commonly used for lymphoscintigraphy in Europe: Albures and

Nanocoll. Albures has a mean particle size of 500 nm and is a slower-moving particle that remains in first echelon (sentinel) nodes but requires a high density of terminal lymphatic vessels at the injection site. For this reason, Albures is the colloid of choice in the tongue and floor of mouth. Nanocoll has a mean particle size of 50 nm and is a faster-moving colloid that finds lymphatic vessels despite injection into tissues with low densities of terminal lymphatics. However, it moves readily from sentinel nodes to subsequent echelon nodes and for these reasons Nanocoll is the colloid of choice in primary tumors that aren’t located in the floor of the mouth or the tongue.

Biopsy procedure

See the list below:

• During surgery, 1-2 mL of patent blue V dye is injected throughout the normal mucosa and submucosa that surrounds the tumor. This should be performed prior to the skin incision. Ensure that the same injection sites are used for Patent blue V and the radiocolloid.

• The primary tumor is removed with adequate margins. In case the primary tumor is not excised first, the problem of the scattered radiation from the primary tumor can be avoided by using lead plates and a well-collimated detector gamma probe.

• A suitable small incision is made in the neck in accordance with the marking done by the nuclear physician.

• After cutting the deeper layers, a hand-held gamma probe is used to identify radioactive sentinel nodes. To reduce "shine through," a series of malleable, sterilized lead plates may be used to mask the injection site.

• Radioactive nodes are excised and radioactivity within the node is confirmed ex vivo.

• Blue stained lymphatic pathways are followed to the first draining lymph, which is harvested. Sentinel nodes are labeled according to their color and radioactivity.

• The anatomical level of sentinel nodes is noted.

Pathology

Sentinel nodes are fixed in 10% neutral buffered formalin and, after fixation, are bisected through the hilum, if this is identifiable, or through the long axis of the node. If the thickness of the halves is more than 2 mm, the slices are further trimmed to provide additional 2 mm blocks. If the sentinel nodes are found to be free from tumor on initial histological examination, step-serial sections are prepared at an additional 6 levels in the block at approximately 150 μm intervals. One hematoxylin and eosin stained section is prepared at each level. If the nodes still appear histologically negative, an immediately adjacent section from each level is examined by immunocytochemistry, using the multicytokeratin antibody.

Management of the neck following organ preservation protocols

The management of neck has evolved over the last few decades, owing to the morbidity of radical procedures, better understanding of the patterns of spread, and the successful introduction of chemoradiotherapy protocols. With the advent of organ preservation protocols for advanced head and neck cancers, the role of neck dissection has been primarily restricted to the adjuvant setting. Adjuvant neck dissection is typically performed after completion of chemoradiotherapy regimen, either as a part of planned neck dissection irrespective of neck response (usually 6-10 wk posttreatment) or as a salvage surgery for residual neck disease.

Although consensus states that N1 neck disease does not mandate a adjuvant neck dissection, controversies persist for N2/N3 neck disease treated with organ preservation protocols. Proponents of adjuvant neck dissection have shown a higher rate of regional failure and detrimental survival in patients who do not undergo neck dissection.[40] Approximately 25%of patients who achieve complete response and subsequently undergo a planned neck dissection have persistent disease in the surgical specimen. Alternatively, 30-40% of partial responders who undergo a neck dissection show no viable disease. Hence, the accuracy of neck assessment using conventional clinical and radiological yardsticks is only 60%.[41]

Nuclear imaging using PET-CT scanning has improved the accuracy of assessment in the postchemoradiotherapy setting. Studies have shown PET-CT scanning has a high negative predictive value (as high as 100%),[42] thus making adjuvant neck dissection unnecessary in all cases of N2/N3 disease. A negative PET scan result is a fairly accurate indicator that the neck does not harbor any residual disease. However, a positive scan finding does not necessarily signify persistent disease. Most studies recommend 8-12 weeks as the optimal time for response assessment to reduce the chances of false positive results.

The consensus statement on the management of neck after chemoradiotherapy recommended observation of patients with initial N1 and N2 disease who achieved complete response after chemoradiotherapy. The complete response rate reduces from 80% for N1 nodes to about 40% for N3 nodes. Thus, in patients with N3 neck nodes, close observation may be advocated only in patients with a negative PET-CT scan finding.[43] Assessment of partial responders appears to be more complex, with as many as 60% having pathologically negative neck nodes on adjuvant neck dissection despite using stringent radiological criteria. Hence, neck dissection may be unnecessary in almost two thirds of this group.

Although PET-CT scanning is an invaluable tool in this scenario, the cost of this investigation limits its use in basic resource settings. Ultrasonographic-guided fine-needle aspiration cytology (FNAC) may be a viable alternative in this setting.[44] van der Putten et al reported a sensitivity as high as 80% with ultrasound-guided FNAC. Although the cytological features of nodes after chemoradiotherapy have not been extensively studied, the presence of viable tumor cells rather than necrotic cells could guide decision-making in this scenario.[45]

Selective neck dissection in management of the node-positive neck

Practice of selective neck dissection has been a debatable issue in a node-positive setting. The key issue revolving around such a practice is the increase in the regional failure rates. The incidence of regional failures steadily increases with the volume of neck diseases, nodal staging, and involvement of nonlymphatic structures or extracapsular spread. Regional recurrence rates of up to 13% have been noted in this scenario.[46, 47] The rate of failure in node positive-settings was significantly reduced by the addition of adjuvant radiotherapy (35.7% vs 5.6%).[46, 48] Selective neck dissection is not used for patients with high volume/N3 neck disease. Regional control rates comparable with comprehensive neck dissections may be achieved in appropriately selected patients.