Residency · Residency · Otolaryngology

Oral Cavity Cancer: Surgical Management

Overview

Oral cavity squamous cell carcinoma (OCSCC) is primarily a surgically managed disease. The oral cavity spans from the vermilion border of the lips to the junction of the hard and soft palate superiorly and the circumvallate papillae inferiorly. Surgical principles include adequate margin resection, appropriate management of the neck, and functional reconstruction. Management of the clinically N0 neck remains an area of active debate.

Anatomy and Subsites

Lips: vermilion and mucosal surface. Oral tongue (anterior 2/3): mobile tongue anterior to circumvallate papillae. Floor of mouth: between the ventral tongue and the mandibular alveolus. Buccal mucosa: inner cheek lining. Alveolar ridge/gingiva: upper and lower. Hard palate: bony palate mucosa. Retromolar trigone (RMT): mucosa overlying the ascending ramus posterior to the last molar.

Epidemiology and Risk Factors

Oral tongue is the most common subsite in the Western world. Tobacco (smoked and smokeless) and alcohol: strongest risk factors; synergistic. Betel quid/areca nut: major risk in South and Southeast Asia. Chronic irritation, poor oral hygiene, Lichen planus, oral submucous fibrosis (premalignant). HPV: minor role in oral cavity (more significant in oropharynx). Increasing incidence in young patients without traditional risk factors (especially oral tongue).

Clinical Presentation

Non-healing ulcer or mass in the oral cavity, Pain, bleeding, loose teeth, Referred otalgia (via CN V, lingual nerve), Trismus (pterygoid muscle involvement -- advanced disease), Dysphagia, dysarthria, Neck mass (cervical lymphadenopathy).

Workup

Biopsy of the primary lesion (incisional biopsy in clinic or OR). Bimanual palpation of the floor of mouth and tongue base. CT neck with contrast: primary tumor extent, mandible invasion, nodal disease. MRI: superior for tongue and floor of mouth assessment; depth of invasion measurement. CT chest or PET/CT for advanced disease, Dental evaluation pre-treatment, Nutritional assessment.

Staging (AJCC 8th Edition -- Oral Cavity)

T-Staging (Size AND Depth of Invasion)

T1: tumor ≤2 cm AND DOI ≤5 mm. T2: tumor ≤2 cm with DOI >5-10 mm, OR tumor >2-4 cm with DOI ≤10 mm. T3: tumor >4 cm OR DOI >10 mm. T4a: tumor invades cortical bone of mandible/maxilla, maxillary sinus, or skin of face. T4b: tumor invades masticator space, pterygoid plates, skull base, or encases internal carotid artery. DOI is measured from the basement membrane of adjacent normal mucosa perpendicularly to the deepest point of invasion (not tumor thickness).

Surgical Principles

Margin Goals

Minimum 1 cm macroscopic mucosal margin in all directions, Minimum 1 cm deep margin, Frozen section analysis of margins intraoperatively. Close margin: <5 mm microscopically; positive margin: tumor at the inked edge. Re-resection of positive or close margins when feasible.

Approaches to the Primary

Transoral: for small, accessible tumors (T1-T2) of the oral tongue, floor of mouth, buccal mucosa. Lip-splitting mandibulotomy (visor or mandibulotomy with paramedian osteotomy): provides wide access to the posterior oral cavity and oropharynx; mandible is divided and plated after tumor resection. Cheek flap/lateral approach: for buccal and RMT tumors. Pull-through: resection of the tongue/floor of mouth delivered through the neck without mandibulotomy.

Mandible Management

Marginal (rim) mandibulectomy: if tumor abuts but does not invade the mandible cortex; removes the superior rim while preserving mandibular continuity. Segmental mandibulectomy: if tumor invades the mandible cortex or medullary bone; requires bone reconstruction (fibula free flap). Panorex or CT with bone windows to assess mandibular invasion. Periosteal involvement alone may allow marginal mandibulectomy.

Management of the Neck

Clinically N+ Neck

Therapeutic neck dissection (selective or modified radical) at the time of primary resection. Levels I-IV typically included for oral cavity primary. Adjuvant radiation or chemoradiation based on pathologic findings.

Clinically N0 Neck [CONTROVERSY]

Occult nodal metastasis rate for oral tongue SCC: 20-30% for T1-T2 tumors. Elective neck dissection (END): standard for T2-T4 tumors and T1 tumors with DOI >4 mm. Sentinel lymph node biopsy (SLNB): increasingly validated alternative to END for T1-T2 N0 oral cavity SCC; SENT trial demonstrated feasibility and accuracy. Selective neck dissection levels I-III (supraomohyoid neck dissection) is standard END for oral cavity. DOI as a predictor of occult nodal metastasis: DOI ≤3-4 mm: ~10% occult nodal rate; observation may be reasonable. DOI >4 mm: ≥20% occult nodal rate; END recommended. Watchful waiting with serial US and examination: alternative for thin tumors (DOI ≤3 mm); requires reliable follow-up.

Reconstruction

Primary closure: small defects, particularly floor of mouth and buccal mucosa. Skin graft (split-thickness): for superficial defects with a well-vascularized bed. Local flaps: facial artery musculomucosal (FAMM) flap, nasolabial flap, tongue flap. Pedicled flaps: pectoralis major myocutaneous flap (workhorse for coverage when free flap unavailable or contraindicated); submental island flap. Free flaps: Radial forearm free flap (RFFF): thin, pliable; ideal for tongue and floor of mouth reconstruction; allows speech and swallowing rehabilitation. Anterolateral thigh (ALT) flap: versatile; can be thinned; good for larger soft tissue defects. Fibula free flap: osteocutaneous; gold standard for mandibular reconstruction after segmental mandibulectomy. Scapula free flap: bone (scapular tip) and soft tissue components; alternative to fibula.

Adjuvant Therapy

Radiation alone: for adverse features including close margins, perineural invasion, lymphovascular invasion, pT3-T4, multiple positive nodes. Concurrent chemoradiation (cisplatin): for positive margins and/or extranodal extension. Intensity-modulated radiation therapy (IMRT) to minimize toxicity. Radiation typically starts within 6 weeks of surgery.

<image>Anatomical diagram of the oral cavity showing the subsites relevant to oral cavity squamous cell carcinoma. The oral tongue (anterior 2/3), floor of mouth, buccal mucosa, alveolar ridges, hard palate, retromolar trigone, and lips are labeled with their boundaries. The circumvallate papillae marking the junction between oral tongue and tongue base, and the hard-soft palate junction are indicated. The relationship of the oral cavity to the oropharynx is shown.</image>

<image>Illustration demonstrating depth of invasion (DOI) measurement in oral cavity SCC according to AJCC 8th edition. A cross-section through the oral tongue showing a tumor with the mucosal surface, basement membrane, and deepest point of tumor invasion. A horizontal line is drawn at the level of the basement membrane of adjacent normal mucosa, and DOI is measured perpendicularly from this line to the deepest point of invasion. Tumor thickness (a different measurement from the tumor surface) is shown for comparison. T-staging thresholds (5 mm and 10 mm DOI) are indicated with dotted lines.</image>

<image>Surgical planning diagram for mandibular management in oral cavity cancer. Top panel: marginal (rim) mandibulectomy showing removal of the alveolar portion of the mandible while preserving the inferior border and mandibular continuity, appropriate when tumor abuts but does not invade cortical bone. Bottom panel: segmental mandibulectomy showing a full-thickness segment of mandible removed, requiring reconstruction with a fibula free flap. The fibula osteocutaneous flap is shown harvested, osteotomized, and plated into the mandibular defect with a skin paddle for intraoral soft tissue coverage.</image>

Clinical Pearls

Depth of invasion (DOI) is the single most important histopathologic parameter in oral cavity SCC: it drives both T-staging and the decision for elective neck dissection. A DOI >4 mm is the threshold at which elective neck dissection is generally recommended for clinically N0 oral tongue SCC. Always perform bimanual palpation of the floor of mouth and tongue -- it provides critical information about deep extent not visible on surface examination. The minimum acceptable margin is 1 cm grossly; frozen section should be sent on all margins and the deep surface. Positive margins and extranodal extension are the two indications for adjuvant chemoradiation (not radiation alone). The fibula free flap is the gold standard for mandibular reconstruction; always assess lower extremity vascular supply (CT angiogram or ankle-brachial index) preoperatively. Trismus suggests pterygoid muscle or masticator space involvement (T4b) and may indicate unresectable disease. Lip SCC has a different biology: better prognosis when sun-related; worse prognosis with inner lip/commissure involvement.

References

• Lydiatt WM, Patel SG, O'Sullivan B, et al. "Head and neck cancers -- major changes in the AJCC 8th edition." CA Cancer J Clin. 2017;67(2):122-137.
• D'Cruz AK, Vaish R, Kapre N, et al. "Elective versus therapeutic neck dissection in node-negative oral cancer." N Engl J Med. 2015;373(6):521-529.
• Civantos FJ, Zitsch RP, Schuller DE, et al. "Sentinel lymph node biopsy accurately stages the regional lymph nodes for T1-T2 oral squamous cell carcinomas." J Clin Oncol. 2010;28(8):1395-1400.
• National Comprehensive Cancer Network (NCCN). "Head and Neck Cancers." Version 2.2024.

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