12 Head and Neck Cancer
Pathology
Usually squamous cell carcinoma that, if small, will spread to ipsilateral nodes, but if abuts midline or is large, it may spread to contralateral nodes. 2
Genetics
Human papilloma virus (HPV) infection also plays a role and those tumors related to HPV have a better prognosis since these patients present younger and are less likely to have a significant alcohol and tobacco history. They do, however, have a history of multiple sex partners and are less likely to have a second primary tumor. 3
Staging 4
Tumor
T1 = 2 cm or less in diameter.
T2 = 2 to 4 cm in diameter.
T3 = Greater than 4 cm in diameter.
T4 = Tumors that invade or encase adjacent structures.
Lymph Nodes
Lymph nodes are classified by levels:
I = Submental and submandibular.
II = Superior third of jugular vein nodes, from digastric muscle to carotid bifurcation.
III = Middle third of jugular vein nodes, from carotid bifurcation to cricothyroid notch or omohyoid muscle.
IV = Lower third of jugular vein nodes, from cricothyroid notch or omohyoid muscle to the clavicle.
V = Posterior triangle nodes and supraclavicular nodes.
VI = Anterior compartment nodes from hyoid bone to suprasternal notch.
N1 = Metastasis in a single ipsilateral node that is 3 cm or less in greatest dimension.
N2a = Single ipsilateral node is 3 to 6 cm in greatest dimension.
N2b = Metastasis in multiple ipsilateral nodes is not greater than 6 cm in greatest dimension.
N2c = Metastasis in bilateral or contralateral nodes is not greater than 6 cm in greatest dimension.
N3 = Metastasis in node is great than 6 cm in greatest dimension.
Metastases
M0 = No metastases.
M1 = Metastases present.
Staging
Stage I = T1N0M0.
Stage II = T2N0M0.
Stage III = T3N0M0 or T1–T3N1M0.
Stage IVA = T4a, N0–1, M0.
Stage IVB = Any T, N3M0 or T4b, any N, M0.
Stage IVC = Any T, any N, M1.
Treatment
Surgery
Resection of the tumor is a mainstay of therapy for this tumor. A neck dissection is performed to evaluate the lymph nodes in levels I to V. The radical neck dissection will remove all nodes and the contiguous structures including the sternocleidomastoid muscle, the omohyoid muscle, internal and external jugular veins, cranial nerve XI, and the submandibular gland. The modified radical neck dissection will spare cranial nerve XI (type I), cranial nerve XI and the internal jugular vein (type 2), or cranial nerve XI, the internal jugular vein, and the sternocleidomastoid muscle (type3). The last is considered to be the most functional result. 5
Patients are considered to be at low risk (20%) for neck disease when it is not clinically evident in T1 tumors of the floor of mouth, oral tongue, retromolar trigone, gingiva, hard palate, or buccal mucosa (group 1). Those at intermediate risk (20–30%) include those patients with T1 tumors of the soft palate, pharyngeal wall, supraglottic larynx, or tonsil or T2 tumors of group 1 mentioned earlier. Those patients at high (>30%) risk of neck disease are those with T1–T4 tumors of the nasopharynx, pyriform sinus, base of tongue or T2–T4 tumors or the soft palate pharyngeal wall, supraglottic larynx, or tonsil, or T3–T4 tumors of the earlier-mentioned group 1. Patients who develop lymph node metastases in the neck after having the primary tumor successfully addressed by surgery or radiotherapy (RT) have a salvage rate of 50 to 60%. 6 An elective neck dissection is indicated when the risk of nodal spread is 10 to 15%. Modified neck dissection techniques can be used with better functional results. Patients found to have nodal disease are then treated with RT or chemoradiotherapy.
The surgery for these lesions is obviously complex and requires the use of free flaps transposed to cover the defects. Transoral robotic surgery (TORS) is the latest minimally invasive technique to be utilized to treat lesions in the oral cavity. 7
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