Oral cavity

Subsites/anatomy
Oral tongue - Retromolar trigone - Gingiva - Buccal mucosa - Floor of mouth - Hard palate

Boundary between oral tongue and base of tongue = circumvallate papillae

Posterior boundary of floor of mouth = anterior tonsillar pillar

Lymph node patterns of spread
For clinically N0, + nodes found in 15 - 20% at neck dissection
Nodal risk increases with size of tumor, depth of invasion
Most commonly involved levels are I, II; III and IV are more frequently involved in clinically N+ pts
Oral tongue lesions are associated with skip metastasis into levels II and III/IV

Upper lip --> preauricular and parotid nodes; level I
Lower lip --> level I
Oral tongue --> level I; level II directly (particularly in more posterior lesions); bilateral/crossed drainage is common; skip metastasis
Floor of mouth --> level I
Buccal mucosa --> parotid; level I
Retromolar trigone --> level II; retropharyngeal nodes
Hard palate --> Rare lymph node mets if lesion confined to the hard palate; I, II, retropharyngeal

Epidemiology
~12,000 cases per year (30% of all head and neck cancers)
5-year OS for all patients is about 60%

Risk factors
Tobacco
Alcohol
Betel nut chewing
HPV (6 and 16 subtypes)
Plummer-Vinson syndrome
Prior oral cavity cancer: elevated risk ~4% per year for another oral cavity cancer; patients are also at much higher risk for esophageal (RR ~20) and lung (RR~7) cancers

Pathology
95% of oral cavity tumors are squamous cell
Premalignant lesions include leukoplakia (5-20% risk of progression to cancer) and erythroplakia (much higher risk of progression to cancer, up to 50%)
Subtypes: basaloid thought to be more aggressive and verrucous possibly less aggressive

Prognostic factors
Nodal involvement*
Thickness of primary lesion, PNI, LVSI predict for LN involvement

Treatment
Surgery is the mainstay
Adjuvant RT is commonly indicated +/- chemotherapy

NCCN Recommendations for Adjuvant RT
T3-4 primary
N2-3 nodes
Perineural invasion
LVSI/tumor embolism
Nodal spread to level IV or V

NCCN Recommendations for Adjuvant Chemo + RT
Extracapsular nodal spread
Positive margins

Doses
Primary: at least 60Gy
ECE or +margin areas: 66Gy
Prophylactic neck: 50Gy
Positive neck: 60Gy

EORTC/RTOG pooled analysis (PMID 16161069)
Eligible patients:
EORTC: Stage III - IV; oral cavity or oropharynx primary with level IV node; +PNI; +LVSI
Both studies: + margin, + ECE
RTOG: Two or more positive nodes

Endpoints: EORTC was PFS; RTOG was OS

Randomization was RT +/- cisplatin based chemotherapy

Both studies showed a local control benefit to adding chemo (~70 vs 80% in both) as well as a PFS benefit (36 vs. 47% at 5 years in both trials).

Only the EORTC study showed a significant OS benefit at 5 years (40 vs 53% in EORTC; 47 vs 56% in RTOG).

For patients with ECE or positive margins, OS benefit was evident in both trials

When neither factor was present, no OS benefit was seen in either trial.