Management of the N0 Neck

Frequency

The basic rule for prophylactic treatment of the N0 neck is to treat any patient whose risk of occult lymph node metastases is greater than 15-20%. The risk of regional lymph node metastases varies according to primary site and stage. Areas such as the glottis carry a relatively low risk (< 4% for a T1 lesion), whereas the risk in a site such as the tongue base is as high as 55%. The prevalence of occult neck metastases by site is as follows:

• Floor of mouth - 25%

• Oral tongue - 60%

• Buccal mucosa - 20%

• Retromolar trigone - 20%

• Hard palate - 15%

• Alveolus - 15%

• Tonsil - 36%

• Tongue base - 55%

• Epiglottis - 15%

• False vocal cord - 15%

• Aryepiglottic fold - 30%

• True vocal cord - 15%

• Pyriform sinus - 65%

The following are the lymphatic drainage nodes and the corresponding tumor locations from which they receive drainage:

• Level 1A nodes

  • Lip

  • Anterior mandibular alveolar ridge

  • Floor of the mouth

• Level 1B nodes

  • Oral cavity

  • Anterior nasal cavity

  • Soft tissues and structure of the mid face

• Level 2 nodes

  • Oral cavity

  • Nasal cavity

  • Nasopharynx

  • Oropharynx

  • Hypopharynx

  • Larynx

  • Parotid gland

• Level 3 nodes

  • Oral cavity

  • Nasopharynx

  • Oropharynx

  • Hypopharynx

  • Larynx

• Level 4 nodes

  • Hypopharynx

  • Larynx

  • Cervical esophagus

• Level 5 nodes

  • Nasopharynx

  • Oropharynx

• Level 6 nodes

  • Thyroid gland

  • Larynx (glottic and subglottic)

  • Apex of the pyriform sinus

  • Cervical esophagus

• Retropharyngeal nodes

  • Nasopharynx

  • Maxilla

  • Tonsil

  • Oropharynx

  • Hypopharynx

  • Pyriform sinus

  • Parathyroid cancer

  • Cervical esophagus

Obtain patient's history and perform a complete head and neck physical examination. Although detailing a proper history taking for a head and neck examination is beyond the scope of this chapter, the following signs and symptoms should increase the index of suspicion for possible malignancy:

• Nerve deficit

• Obstruction (nasal, airway, digestive)

• Epistaxis

• Persistent sore throat

• Persistent globus sensation

• Hoarseness

• Stridor

• Leukoplakia

• Erythroplakia

• Neck node

• Masses or nodules in the head and neck region

• Ulceration

• Dysphagia

The indication for treating the N0 neck with surgery or radiation is a risk of occult metastases in excess of 15-20%.

Surgery (elective neck dissection) is indicated if the patient is undergoing surgery for the primary lesions. This approach allows accurate staging because it is supported by histologic studies.

A study by Pfisterer et al found that in patients with SCCA of the parotid gland who had an N0 neck, 5-year disease-specific survival was 78.3% for those who underwent elective neck dissection, compared with 51.1% for those who did not. The study used data from the Surveillance, Epidemiology, and End Results (SEER) registry. ^[2]

In a retrospective study, Philip and James recommended that level 1-3 ipsilateral neck dissection be performed in patients with intraoral maxillary SCCA with an N0 neck. The study, which included 39 patients, found that N0 patients who did not undergo neck dissection had a similar progression rate to disease development as patients with an N+ neck, while ipsilateral neck disease seemed to be resolved in N0 patients who underwent ipsilateral neck dissection. ^[3]

Radiation in N0 neck cases is indicated in the following situations:

• Radiation of the primary site is possible.

• The patient refuses surgery.

• The patient has significant medical comorbidities such that surgery of this magnitude is contraindicated.

During physical examination or during neck dissection, anatomical boundaries are used to identify the lymph nodal levels. The radiologic boundaries are used as reference points during the reading of radiologic images and identification lymph node nodal levels.

The anatomical and radiologic nodal boundaries are as follows:

• Level 1 (submental and submandibular lymph nodes)

  • Anatomic borders

    • Level 1A (submental nodes) boundaries include the anterior belly of digastric and hyoid bone.

    • Level 1B (submandibular nodes) boundaries include the anterior belly and posterior belly, body of the mandible, and the lymph nodes in the facial vessels.

  • Radiologic borders: Nodes are above the hyoid bone, superficial to the mylohyoid and anterior to the transverse line drawn through the posterior edge of the submandibular gland.

• Level 2 (superior jugular nodes)

  • Anatomic borders

    • Lymph nodes are anterior to and behind the great vessels, extending from the skull base to the carotid bifurcation and between the sternohyoid muscle anteriorly and the posterior border of the sternocleidomastoid muscle posteriorly. Level 2 is further divided into A or B using CN 11 as an anatomical reference point.

    • Level 2A (nodes anterior to the spinal accessory nerves [CN 11])

    • Level 2B (nodes posterior to the spinal accessory nerve)

  • Radiologic borders: Lymph nodes are along the superior aspect of the jugular vein, extending from the skull base to the inferior aspect of the hyoid bone and between the back of the submandibular gland anteriorly and the posterior border of the sternocleidomastoid muscle posteriorly.

• Level 3 (midjugular nodes)

  • Anatomic borders: Lymph nodes are along the middle third of the jugular vein. They are bounded superiorly by the carotid bifurcation, inferiorly by the omohyoid muscle, anteriorly by the sternohyoid muscle, and posteriorly by the border of the sternocleidomastoid muscle.

  • Radiologic borders: Lymph nodes are along the middle third of the jugular vein, extending from the bottom of the cricoid arch and between the sternohyoid muscle anteriorly and the posterior border of the sternocleidomastoid muscle posteriorly.

• Level 4 (inferior jugular lymph nodes)

  • Anatomic borders: Lymph nodes are along the inferior aspect of the jugular vein and are bounded superiorly by the omohyoid muscle, inferiorly by the clavicle, anteriorly by the sternohyoid muscle, and posteriorly by the posterior border of the sternocleidomastoid muscle.

  • Radiologic borders: Lymph nodes are along the inferior aspect of the jugular vein, extending from the inferior aspect of the cricoid arch to the clavicle, and lying anterior to line connecting the posterior border of the sternocleidomastoid muscle and the posterolateral border of the anterior scalene muscle.

• Level 5 (posterior triangle lymph nodes)

  • Anatomic borders

    • The posterior triangle lymph nodes are bounded anteriorly by the sternocleidomastoid muscle, posteriorly by the trapezius muscle, and inferiorly by the clavicle.

    • Level 5A: Nodes are superior to the level of the cricoid cartilage.

    • Level 5B: Nodes are inferior to the level of the cricoid cartilage.

  • Radiologic borders: Lymph nodes are bounded posteriorly by the trapezius muscle, inferiorly by the clavicle, anteriorly by the posterior border of the sternocleidomastoid muscle above the inferior border of the cricoid arch, and by the line connecting the posterior border of the sternocleidomastoid muscle and the posterolateral border of the anterior scalene muscle below the cricoid arch.

• Level 6 (central compartment lymph nodes)

  • Anatomic borders: The lymph nodes are bounded superiorly by the hyoid bone, laterally by the carotid arteries, and inferiorly by the suprasternal notch.

  • Radiologic borders: Lymph nodes are bounded by the carotid sheath laterally, hyoid bone superiorly, and manubrium inferiorly.

• Retropharyngeal nodes of Rouviere

  • Anatomic borders: The lymph nodes are posterior to the nasopharynx and oropharynx and medial to the carotid arteries.

  • Radiologic borders: Lymph nodes are from the skull base to T4 vertebrae.