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Carcinoma of the Tongue

Overview & Anatomy

1. Oral tongue (anterior 2/3) — from the tip to the circumvallate papillae; part of the oral cavity
2. Base of tongue (posterior 1/3) — from the circumvallate papillae to the vallecula; part of the oropharynx

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Epidemiology

• Oral tongue is the second most common site of oral cancer (30% of all oral cancers)
• Most lesions (≈75%) occur on the posterolateral aspect of the oral tongue; 20% on the anterolateral ventral surface; 3–5% on the dorsal surface
• Typical patient: male, 6th–7th decade, with history of tobacco and/or alcohol use
• Increasing incidence in young patients (18 years old in 1993, up from 4% in 1971) — no clear risk factors identified; increased genetic susceptibility postulated
• At diagnosis, majority (75%) are staged T2 or smaller

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Histology

• Squamous cell carcinoma (SCC) accounts for the vast majority
• Dorsal tongue differential: amyloidosis, median rhomboid glossitis, granular cell myoblastoma, erosive lichen planus
• Submucosal tongue tumors: leiomyoma, leiomyosarcoma, rhabdomyosarcoma, neurofibroma (mesenchymal origin)
• Tonsil tissue at base of tongue → may also give rise to lymphoma

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Risk Factors

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Clinical Presentation

Early

• Erythroplakia (red, inflammatory lesion) — most common presentation of early SCC
• Leukoplakia (white patch) — premalignant lesion
• Painless ulcer or exophytic mass

Late / Advanced

• Painful ulcerated or exophytic mass (see clinical photo below)
• Tongue fixation (invasion of intrinsic/extrinsic muscles)
• Decreased tongue sensation (lingual nerve invasion)
• Deviation on tongue protrusion, fasciculations, atrophy (hypoglossal nerve invasion)
• Alteration in speech and swallowing
• Referred otalgia (via lingual nerve → auriculotemporal nerve)
• Cervical lymphadenopathy

Base of Tongue (BOT) Specific

• Most common: referred otalgia and odynophagia
• Visualization is difficult → early detection is rare
• HPV+ BOT cancer: frequently presents with cervical lymphadenopathy with small primary (occult primary)

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Local Invasion Patterns

• Anterolateral tongue → spreads medially across central raphe to contralateral side, posteriorly to tongue base, inferiorly into suprahyoid muscles
• Inferolateral spread → involves floor of mouth (common)
• Lingual nerve invasion → loss of dorsal tongue sensation
• Hypoglossal nerve invasion → deviation, atrophy, fasciculations
• Extreme lateral extension → direct invasion of mandible → requires composite resection
• BOT tumors → invade larynx, tonsil, soft palate, hypopharynx

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Staging (AJCC 8th Edition)

T-Staging (Oral Cavity — incorporates Depth of Invasion)

Key update (AJCC 8th ed.): Depth of Invasion (DOI) was added to T-staging. Thin tumors (<2 mm DOI) have minimal regional metastatic potential; thick tumors (>8–9 mm) have significantly higher risk. - Mulholland & Greenfield's Surgery, p. 1997

N-Staging (Oral Cavity / HPV-negative)

Overall Stage Grouping

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Lymphatic Drainage & Regional Metastasis

• Upper jugular nodes (73%)
• Submandibular nodes (18%)
• Middle jugular nodes (18%)
• Submental nodes (9%)

• 25–33% of lymph node metastases are clinically detectable; 20–25% are occult
• Incidence depends on tumor size and depth of invasion
• Midline dorsum or ventral tongue → bilateral cervical metastasis risk
• Base of tongue → levels II–IV; >60% have detectable nodes at presentation, 20% bilateral
• Distant metastasis in oropharyngeal cancer: ~15–20% (screen with chest CT or PET/CT)

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Prognostic Factors

• pN–: 5-year DSS 88%, OS 75%
• pN+/ECS–: 5-year DSS 65%, OS 50%
• pN+/ECS+: 5-year DSS 48%, OS 30%

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Diagnosis & Workup

1. History & physical examination — thorough oral examination, bimanual palpation
2. Biopsy — most lesions amenable to office biopsy; frozen sections intraoperatively
3. Imaging:
   • CT neck with contrast — assess primary extent, bone involvement, nodal disease
   • MRI — superior for soft tissue invasion, perineural spread
   • PET/CT — for advanced disease, detect distant metastasis
   • Intraoral ultrasound — assess depth of invasion (hypoechoic irregular tumor)
4. Panendoscopy — to rule out synchronous primaries
5. Cranial nerve examination — CN V, VII, X, XII

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Treatment

Oral Tongue

Surgery — Primary Modality

Radiation

• For patients unsuitable for surgery: external beam ± brachytherapy
• Postoperative chemoradiation: positive margins, ENE, multiple positive nodes

Chemotherapy

• T4 tumors: chemoradiation considered; bone involvement usually requires surgery
• Concurrent cisplatin-based chemoradiation is standard for unresectable/adjuvant settings

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Management of the Neck

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Base of Tongue Treatment

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Outcomes / Prognosis

Oral Tongue (5-year survival)

Base of Tongue (5-year survival)

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Key Surgical Margins

• Margin of ≥2.2 mm is the threshold below which local recurrence risk substantially increases (Zanoni et al., 381 patients — adjusted HR 2.25 for margin 0.01–2.2 mm vs. HR 1.17 for 2.3–5.0 mm)
• Tumor bed sampling for frozen section has sensitivity of only 24% for detecting positive margins in early-stage tongue SCC

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Complications of Treatment

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Summary of Key Points

1. Most common histology: SCC; most frequent subsite = posterolateral oral tongue
2. Risk factors: tobacco + alcohol (synergistic); HPV-16 for base of tongue
3. Early sign: erythroplakia; late signs: fixation, otalgia, dysphagia, lymphadenopathy
4. AJCC 8th ed. incorporates DOI into T-staging — critical prognostic variable
5. Primary treatment: surgery (partial glossectomy) for oral tongue; (chemo)radiation or TORS for base of tongue
6. Elective neck dissection: recommended for DOI ≥4 mm even if clinically N0
7. ECS dramatically worsens prognosis; drives adjuvant chemoradiation decision
8. Free flap reconstruction is the standard for defects involving >1/2 tongue or floor of mouth

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• Cummings Otolaryngology Head and Neck Surgery, Chapter 91
• KJ Lee's Essential Otolaryngology, Chapter 45
• Mulholland & Greenfield's Surgery, Chapter 41
• Harrison's Principles of Internal Medicine, 22nd ed.