Background

Question 1

What is the incidence of oral cavity cancer (OCC) in the United States?

Answer 1

∼24,000 cases/yr of OCC in the United States

Question 2

What % of H&N cancers are OCCs?

Answer 2

OCCs comprise 25%–30% of all H&N cancers.

Question 3

What are the anatomical borders and of what structures does the OC consist?

Answer 3

Lips, gingiva, upper/lower alveolar ridge, buccal mucosa, retromolar trigone (RMT), hard palate, floor of mouth (FOM), oral tongue.

Question 4

What is the most and least commonly involved site in OCC?

Answer 4

The lower lip is the most common site (38%), and the buccal mucosa is the least common site (2%). The tongue is involved 22% of the time. (Krolls SO et al., J Am Dent Assn 1976)

Question 5

What CNs provide motor and sensory innervation to the oral tongue?

Answer 5

Motor: CN XII

Sensory: CN V3 (lingual branch)

Question 6

What CNs provide the tongue with taste sensation?

Answer 6

Ant two-thirds of tongue: CN VII (chorda tympani)

Post one-third of tongue: CN IX

Question 7

Which nerve provides motor innervation to the lips?

Answer 7

The facial nerve (CN VII) provides motor innervation to the lips.

Question 8

Where is the ant-most border of the OC?

Answer 8

The vermilion border of the lips is the ant-most border of the OC.

Question 9

Where is the post-most border of the OC?

Answer 9

The hard/soft palate junction superiorly and the circumvallate papillae inferiorly.

Question 10

What are some premalignant lesions of the OC, and which type has the greatest propensity to progress to invasive cancer?

Answer 10

Erythroplakia (∼30% progression rate) and leukoplakia (4%–18% progression rate)

Question 11

What are some risk factors that predispose to OCC?

Answer 11

Tobacco and alcohol. Also, betel nut consumption, periodontal Dz, sun exposure (lip).

Question 12

What are the sup and inf spans of levels II–IV LN chains/levels?

Answer 12

Level II: skull base to bottom of hyoid

Level III: infrahyoid to bottom of cricoid

Level IV: infra-cricoid to clavicles

Question 13

Where are the levels IA–IB nodes located?

Answer 13

Level IA nodes are submental (space b/t the ant belly of the digastric muscles), and level IB nodes are submandibular (space lat the digastric muscle and mandible).

Question 14

Where are the levels V–VI nodes located?

Answer 14

Level V nodes are in the post triangle. Level VI nodes are in the central compartment paratracheal/prelaryngeal region.

Question 15

What is the Delphian node?

Answer 15

The Delphian node is a midline prelaryngeal level VI node.

Question 16

What is the estimated risk of LN involvement with a T1–T2 primary of the lip, FOM, oral tongue, and buccal mucosa?

Answer 16

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.

Question 17

What is the estimated risk of LN involvement with a T3–T4 primary of the lip, FOM, oral tongue, and buccal mucosa?

Answer 17

The risk of LN involvement is ∼33% for the lip and 33%–67% for the other OC T3–T4 primaries.

Question 18

What is the nodal met rate for a T1 vs. T2 lesion of the oral tongue?

Answer 18

The nodal met rate is 14% for T1 tongue lesions and 30% for T2 tongue lesions. (Lindberg R et al., Cancer 1972)

Question 19

What is the overall and stage-by-stage nodal met rate for FOM lesions?

Answer 19

Overall: 20%–30%

T1: 10%

T2: 30%

T3: 45%

T4: >50%

(Lindberg R et al., Cancer 1972)

Question 20

Lesions located where in the OC predispose to bilat LN mets?

Answer 20

Midline and anterolat OC lesions (tongue, FOM) predispose to bilat LN mets.

Question 21

Which OC cancer has the greatest propensity for LN spread?

Answer 21

Oral tongue cancer has the greatest propensity for LN spread.

Question 22

What OC subsite is 2nd only to the oral tongue in propensity for nodal spread?

Answer 22

The alveolar ridge/RMT has the 2nd highest propensity for LN spread (3rd highest is FOM).

Question 23

Can ant oral tongue lesions involve other LN levels without involving level I LNs?

Answer 23

Yes. ∼13% of ant tongue lesions skip the level I LNs. (Byers RM et al., Head Neck 1997)

Question 24

Which anatomic structure divides the oral tongue from the base of tongue (BOT)?

Answer 24

The circumvallate papillae divide the oral tongue from the BOT.

Question 25

What is the most common site of minor salivary cancers?

Answer 25

Hard palate

Question 26

What are common sites of DM for cancers of the OC?

Answer 26

Lungs, bones, and liver

Question 27

What anatomic structure divides the FOM anteriorly into 2 halves?

Answer 27

The lingual frenulum divides the FOM anteriorly.

Question 28

Where is the Wharton duct located, and what gland does it drain?

Answer 28

The Wharton duct opens at the ant FOM (midline) and drains the submandibular gland.

Question 29

From where in the OC do most gingival cancers arise?

Answer 29

Most (80%) gingival cancers arise from the lower gingiva.

Question 30

Do most lip cancers arise from the upper or lower lip?

Answer 30

Most (∼90%) lip cancers arise from the lower lip.

Question 31

What are some benign lesions that arise from the lip?

Answer 31

Benign lip lesions include keratoacanthoma, actinic keratosis, hemangiomas, fibromas, HSV, and chancre.

Question 32

What nodal groups drain the tip of the tongue, the ant tongue, and the post tongue?

Answer 32

Tip of tongue: level IA

Ant tongue: level IB and level III (midjugular)

Post tongue: level IB and level II

Question 33

Which OC site lesions are notorious for skipped nodal mets?

Answer 33

Ant oral tongue lesions can skip levels II–III and involve only level IV (so a full neck dissection is typically needed).

Question 34

What features of lip cancer predict for nodal spread?

Answer 34

DOI, high grade, large size, invasion of buccal mucosa/dermis, or recurrent Dz after resection

Question 35

What nodal stations are involved with upper vs. lower lip lesions?

Answer 35

Upper lip lesions spread to preauricular, facial, parotid, and IA–IB LNs; lower lip lesions spread to levels IA–IB and level II LNs.