Oral Cavity Cancer
Background
What is the incidence of oral cavity cancer (OCC) in the U.S.?
~23,000 cases/yr of OCC in the U.S. (2008 data)
What % of H&N cancers are OCCs?
OCCs comprise 25%–30% of all H&N cancers.
Of what structures does the oral cavity (OC) consist?
Lips, gingiva, buccal mucosa, retromolar trigone (RMT), hard palate, floor of mouth (FOM), and oral tongue
What is the most and least commonly involved site in OCC?
The lip is the most common site (45%), and the hard palate is the least common site (5%). The tongue is involved 16% of the time.
What CNs provide motor and sensory innervation to the oral tongue?
Motor: CN XII
Sensory: CN V (lingual branch)
What CNs provide the tongue with taste sensation?
Anterior two thirds of tongue: CN VII (chorda tympani)
Posterior one third of tongue: CN IX
What nerve provides motor innervation to the lips?
The facial nerve (CN VII) provides motor innervation to the lips.
What nerve provides motor innervation to the tongue?
The hypoglossal nerve (CN XII) provides motor innervation to the tongue.
Where is the ant-most border of the OC?
The vermilion border of the lips is the ant-most border of the OC.
Where is the post-most border of the OC?
The hard/soft palate border superiorly and the circumvallate papillae inferiorly are the post-most borders of the OC.
What are some premalignant lesions of the OC, and which type has the greatest propensity to progress to invasive cancer?
Erythroplakia (~30% progression rate) and leukoplakia (4%–18% progression rate) are premalignant lesions of the OC.
What are some risk factors that predispose to OCC?
Tobacco (smoked or chewed), betel nut consumption, alcohol, poor oral hygiene, and vitamin A deficiency
What are the sup and inf spans of level II–IV LN chains/levels?
Level II: skull base to hyoid
Level III: hyoid to bottom of cricoid
Level IV: cricoid to clavicles
Where are the level IA–IB nodes located?
Level IA nodes are submental, and level IB nodes are submandibular.
Where are the level V–VI nodes located?
Level V nodes are in the post triangle, and level VI nodes are in the paratracheal/prelaryngeal region.
What is the delphian node?
The delphian node is a midline prelaryngeal level VI node.
What are some important risk factors for LN mets in OCC?
Increasing DOI, increasing T stage, muscle invasion, and high-grade histology
What is the estimated risk of LN involvement with a T1-T2 primary of the lip, FOM, oral tongue, and buccal mucosa?
The risk of LN involvement is ~5% for the lip, 20% for the oral tongue, and ~10%–20% for the other OC T1-T2 primaries.
What is the estimated risk of LN involvement with a T3-T4 primary of the lip, FOM, oral tongue, and buccal mucosa?
The risk of LN involvement is ~33% for the lip and ~33%–67% for the other OC T3-T4 primaries.
What is the nodal met rate for a T1 vs. T2 lesion of the oral tongue?
The nodal met rate is 14% for T1 tongue lesions and 30% for T2 tongue lesions. (Lindberg R et al., Cancer 1972)
What is the overall and stage-by-stage nodal met rate for FOM lesions?
Overall: 20%–30%
T1: 10%
T2: 30%
T3: 45%
T4: >50%
(Lindberg R et al., Cancer 1972)
Lesions located where in the OC predispose to bilat LN mets?
Midline and anterolat OC lesions (tongue, FOM) predispose to bilat LN mets.
Which OC cancer has the greatest propensity for LN spread?
Oral tongue cancer has the greatest propensity for LN spread.
What OC subsite is 2nd only to the oral tongue in propensity for nodal spread?
The alveolar ridge/RMT has the 2nd highest propensity for LN spread (3rd highest is FOM).
Can ant oral tongue lesions involve other LN levels without involving level I LNs?
Yes. ~13% of ant tongue lesions skip the level I LNs. (Byers RM et al., Head Neck 1997)
Which anatomic structure divides the oral tongue from the base of tongue (BOT)?
The circumvallate papillae divide the oral tongue from the BOT (per the AJCC). Some use the sulcus terminalis as the border.
What type of tumors arise from the hard palate?
Primarily minor salivary gland tumors (adenoid cystic, mucoepidermoid, adenocarcinoma) arise from the hard palate.
What are common sites of DM for cancers of the OC?
Lungs, bones, and liver
What anatomic structure divides the FOM anteriorly into 2 halves?
The lingual frenulum divides the FOM anteriorly.
Where is the Wharton duct located, and what gland does it drain?
The Wharton duct opens at the ant FOM (midline) and drains the submandibular gland.
From where in the OC do most gingival cancers arise?
Most (80%) gingival cancers arise from the lower gingiva.
Do most lip cancers arise from the upper or lower lip?
Most (~90%) lip cancers arise from the lower lip.
What are some benign lesions that arise from the lip?
Benign lip lesions include keratoacanthoma, actinic keratosis, hemangiomas, fibromas, HSV, and chancre.
What nodal groups drain the tip of the tongue, the ant tongue, and the post tongue?
Tip of tongue: level IA
Anterior tongue: level IB and level III (mid jugular)
Posterior tongue: level IB and level II
Which OC site lesions are notorious for skipped nodal mets?
Oral tongue lesions can skip levels II–III and involve only level IV (so a full neck dissection is typically needed).
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