What epithelial tumors occur in the oral cavity and how should they be evaluated and managed?

Epithelial Tumors in Dentistry

Oral squamous cell carcinoma (OSCC) is the predominant epithelial malignancy in the oral cavity, accounting for approximately 95% of all oral cancers, and requires immediate multidisciplinary team evaluation at high-volume facilities for optimal outcomes 1.

Types of Epithelial Tumors in the Oral Cavity

Malignant Epithelial Tumors

Squamous Cell Carcinoma (SCC)

• Represents 90-95% of oral malignancies 2, 3
• Most commonly affects the tongue, floor of mouth, buccal mucosa, and gingiva
• Risk factors include tobacco use, alcohol abuse, and HPV infection (particularly HPV-16)
• Can develop from premalignant lesions in most cases 4

Salivary Gland Carcinomas

• Mucoepidermoid carcinoma: Can show continuity with oral surface mucosa, demonstrates strong female predilection (6:1) with bimodal age distribution (peaks in 4th and 7th decades) 5
• Adenoid cystic carcinoma: May mimic benign tumors clinically 3

Rare Epithelial Malignancies

• Epithelioid sarcoma: Extremely rare (<1% of sarcomas), characterized by epithelioid cytology with aberrant cytokeratin/EMA expression and loss of SMARCB1 6

Premalignant Lesions

Leukoplakia

• Both homogeneous leukoplakia and erythroleukoplakia require biopsy 4
• Proliferative verrucous leukoplakia carries particularly high malignant transformation risk
• "Field cancerization" must be considered in extensive lesions 4

Other High-Risk Lesions

• Erosive lichen planus
• High-grade dysplasia/carcinoma in situ 4

Evaluation Algorithm

Initial Assessment

Clinical Examination

• Inspect entire oral mucosa during every dental/medical examination 7
• Document lesion size, location, texture, color changes, and ulceration
• Palpate for induration, fixation to underlying structures
• Examine for cervical lymphadenopathy

Biopsy Protocol

• All suspicious lesions require tissue diagnosis 4, 8
• Low-grade dysplasia: Can be observed with interval biopsies if indicated
• High-grade dysplasia/carcinoma in situ: Requires surgical removal 4
• Brush biopsy, imaging techniques, and molecular tests are NOT reliable enough for definitive diagnosis 4

Imaging for Confirmed Malignancy

Cross-Sectional Imaging (Primary Modality)

• CT with contrast (3-5mm sections, axial and coronal): Best for evaluating mandibular/maxillary bone erosion and cervical lymph node metastases 3
• MRI with contrast (T1, T2, T1-Gd-DTPA): Superior for soft tissue assessment, preferred for tongue carcinomas, oropharyngeal cancers, and tonsillar lesions 3
• Noncontrast imaging limits accurate tumor margin delineation critical for T-staging 9

Ultrasound

• Effective first-line for superficial parotid and submandibular gland tumors 9
• Allows Doppler assessment and FNA guidance
• Limitations: Cannot assess deep parotid lobe, perineural spread, bone invasion, or retropharyngeal nodes 9

PET Scanning Indications 3

• Unknown primary with cervical metastases
• Suspected recurrence
• Inconclusive CT findings for nodal metastases

Management Based on Stage

Early Disease (T1-T2, N0)

Single-modality treatment is preferred 1:

• Complete surgical excision with adequate margins
• OR definitive radiation therapy (IMRT/VMAT mandatory) 1
• Treatment choice depends on functional outcome expectations and patient factors

Locally Advanced Disease (T3-T4 or Node-Positive)

For T3/T4 Oral Cavity Cancers: Primary surgical treatment followed by adjuvant RT or chemoradiotherapy is preferred 1:

• Complete tumor resection with neck dissection
• Postoperative RT indicated for: pT3-4 tumors, R1/R2 resection margins, perineural infiltration, lymphatic infiltration, >1 invaded lymph node, extracapsular extension 1
• Postoperative chemoradiotherapy mandatory for: R1 resection AND extracapsular rupture 1
• Must initiate within 6-7 weeks of surgery 1

Alternative for Locally Advanced Disease:

• Primary concurrent chemoradiotherapy (70 Gy with cisplatin 100 mg/m² on days 1,22,43) 1
• For cisplatin-unfit patients: carboplatin/5-FU, cetuximab with RT, or hyperfractionated/accelerated RT 1

Recurrent/Metastatic Disease

First-Line Treatment (PD-L1 CPS ≥1):

• Pembrolizumab + platinum/5-FU when rapid tumor shrinkage needed 1
• Pembrolizumab monotherapy as alternative 1

For PD-L1-Negative Tumors:

• Platinum/5-FU/cetuximab remains standard 1

Second-Line (Progression within 6 months of platinum):

• Nivolumab (FDA/EMA-approved, improved OS: 7.5 vs 5.1 months) 1

Post-Progression on Platinum and Anti-PD-1:

• No standard of care exists
• Cetuximab, taxanes ± cetuximab/methotrexate used empirically 1

Critical Management Principles

Biomarker Testing

• p16 IHC: Surrogate for HPV-induced oropharyngeal cancer (prognostic, but treatment remains same as HPV-negative) 1
• PD-L1 IHC: Required for pembrolizumab monotherapy eligibility 1
• DPD testing: Mandatory before 5-FU initiation 1

Common Pitfalls to Avoid

1. Diagnostic Errors: Epithelioid sarcoma can mimic carcinoma due to cytokeratin/EMA positivity—always include SMARCB1 in immunopanel for epithelioid lesions 6

2. Inadequate Imaging: Noncontrast studies compromise surgical planning by limiting tumor margin delineation 9

3. Delayed Adjuvant Therapy: Starting RT/CRT >7 weeks post-surgery worsens outcomes 1

4. Unnecessary Neck Dissection: Avoid in patients with negative FDG-PET and normal-sized nodes at 12 weeks post-CRT 1

5. Overlooking Field Cancerization: Extensive premalignant lesions require comprehensive mapping 4

6. Relying on Non-Biopsy Diagnostics: Brush biopsy and molecular tests lack sufficient reliability for definitive diagnosis 4