31.6 Oral Squamous Cell Carcinoma, Urgent Referral and Biopsy

Oral Squamous Cell Carcinoma (OSCC)

Oral Squamous Cell Carcinoma (OSCC) represents greater than 90% of all primary malignant neoplasms of the oral cavity. It arises from the stratified squamous epithelium of the oral mucosa through a multistep accumulation of genetic mutations in oncogenes (e.g., EGFR, cyclin D1) and tumour suppressor genes (e.g., TP53, CDKN2A/p16).

                                  Etiology & Synergy in OSCC
                                              │
     ┌──────────────────┬─────────────────────┴─────────────────────┬──────────────────┐
     ▼                  ▼                                           ▼                  ▼
Tobacco Smoking     Alcohol Abuse                              Areca Nut          Human Papillomavirus
• Polycyclic        • Ethanol -> Acetaldehyde                   • Arecoline        • HPV-16 & HPV-18
  hydrocarbons      • Increases mucosal permeability            • Chronic fibrosis • Oropharyngeal SCC
• Nitrosamines        to tobacco carcinogens                    • Direct DNA       • Tonsillar / base of tongue
• 5–10x risk        • Dehydrates oral epithelium                  damage           • p16+ biomarker
         │                  │                                                      • Better prognosis
         └────────┬─────────┘
                  ▼
        SYNERGISTIC MULTIPLICATION
        (Combined risk up to 30–50x)

Etiological Risk Factors

1. Tobacco Usage: The predominant preventable cause. Cigarette, cigar, and pipe smoke contain over 70 identified carcinogens, notably polycyclic aromatic hydrocarbons (PAHs) and tobacco-specific nitrosamines (NNN, NNK), which form bulky covalent DNA adducts and induce transversion mutations in TP53.
2. Alcohol Consumption: Ethanol itself is not a direct carcinogen, but its primary metabolite, acetaldehyde, is mutagenic, cross-linking DNA and causing chromosomal aberrations. Furthermore, alcohol acts as an organic solvent, dehydrating and increasing the permeability of the oral epithelium to tobacco-derived carcinogens, while inducing cytochrome P450 2E1 (which activates pro-carcinogens).
3. Synergistic Multiplicative Risk: When heavy tobacco smoking is combined with heavy alcohol consumption, the risk is not merely additive—it is synergistic and multiplicative, elevating the relative risk of oral cancer by 30 to 50 times compared to non-smoking, non-drinking controls.
4. Human Papillomavirus (HPV):
   • High-risk strains HPV-16 and HPV-18 produce oncoproteins E6 (which binds and degrades p53 via ubiquitin ligase) and E7 (which binds and inactivates retinoblastoma protein pRb, causing compensatory hyperaccumulation of p16INK4a).
   • Crucial UK Examination Distinction: HPV is primarily implicated in Oropharyngeal Squamous Cell Carcinoma (OPSCC) affecting the lymphoid tissues of the palatine tonsils, tonsillar pillars, base of the tongue, and posterior pharyngeal wall. It is rarely causative in conventional oral cavity OSCC (anterior two-thirds of the tongue, floor of the mouth, buccal mucosa). HPV-positive OPSCC occurs in a distinctly younger demographic, often non-smokers and non-drinkers, and carries a significantly better overall prognosis and superior responsiveness to chemoradiotherapy compared to smoking-related, HPV-negative OSCC.

High-Risk Anatomical Sites in the UK

In the UK, over 75% of intraoral cancers arise within the "gutter" or "drainage basin" of the mouth—where pooling of saliva containing concentrated dissolved tobacco and alcohol carcinogens occurs against thin, vulnerable, non-keratinised mucosa:

1. Lateral border and ventral surface of the tongue (~40–50% of all oral carcinomas).
2. Floor of the mouth (~25–30%).
3. Retromolar trigone and tonsillar pillar complex.

Clinical Presentations & "Red Flag" Symptoms

Early OSCC is frequently painless and asymptomatic, emphasizing the necessity of thorough soft-tissue screening at every routine dental examination. Classical manifestations include:

1. Indurated Ulceration: A solitary, persistent ulcer presenting with raised, everted, rolled margins and a sloughing, indurated, firm, necrotic base that is hard on bimanual palpation. Any ulcer persisting >3 weeks is malignant until proven otherwise.
2. Exophytic / Fungating Mass: A proliferating, cauliflower-like, papillary, or verrucous mucosal growth with irregular surface ulceration, bleeding easily upon contact.
3. Erythroplakic / Erythroleukoplakic Patches: Persistent granular red or speckled velvety plaques.
4. Unexplained Mobility of Teeth: Localised, rapid loosening of teeth without established, generalized periodontal disease, or failure of an extraction socket to heal (a "heaped-up" socket containing friable red granulation tissue).
5. Neurological Deficits: Paresthesia, numbness, or dysaesthesia of the lower lip, chin, or tongue (Vincent's symptom), indicating perineural invasion or destruction of the inferior alveolar/lingual nerve canal.
6. Cervical Lymphadenopathy: A firm, hard, painless, non-tender, fixed, or matted lymph node in the neck (Levels I, II, or III). Metastasis to regional lymph nodes cuts five-year survival in half.

UK Two-Week Wait (2WW) Suspected Cancer Referral Criteria

Under the National Institute for Health and Care Excellence (NICE) Guideline NG12 (Suspected cancer: recognition and referral), general dental practitioners have a statutory professional duty to refer patients through the urgent suspected cancer Two-Week Wait (2WW) pathway directly to a local Oral and Maxillofacial Surgery (OMFS) or Head and Neck Oncology multidisciplinary team (MDT).

                               NICE NG12 Oral Cancer 2WW Criteria
                                               │
     ┌──────────────────┬──────────────────────┴──────────────────────┬──────────────────┐
     ▼                  ▼                                             ▼                  ▼
Unexplained Ulcer   Unexplained Swelling / Lump                   Erythroplakia /    Cervical Node
• In the oral cavity• In the neck (persistent, firm)              Erythroleukoplakia • Unexplained
• Persisting for    • On the lip or in the oral cavity            • Persistent red   • Firm, hard, or
  MORE THAN 3 WEEKS • Hard, fixed, or enlarging                     or red-and-white   fixed neck lump
                                                                    patches

[!IMPORTANT] Statutory NHS 2WW Standard: Under the 2WW mandate, the hospital trust must ensure that the patient is formally evaluated by a named specialist within 14 calendar days of the electronic referral receipt. Dentists must never adopt a "wait and see" approach, perform prolonged empirical antibiotic trials, or attempt repeat topical dressings on an unexplained ulcer persisting >3 weeks. The referral form must clearly state the clinical description, anatomical site, duration, and patient risk factors.

Biopsy Principles in Oral Pathology

A biopsy is the definitive gold standard investigation for establishing a histopathological diagnosis of suspected OPMDs or OSCC.

Incisional vs Excisional Biopsy

• Incisional Biopsy: Removal of a selected representative portion of a lesion along with an adjacent zone of normal tissue. Mandatory for: large lesions (>1 cm), any lesion suspected of being malignant (OSCC), diffuse inflammatory disorders (OLP, pemphigoid), and OPMDs (erythroplakia).
• Excisional Biopsy: Complete removal of the entire lesion with a margin of healthy tissue in a single procedure. Indicated only for small (<1 cm), clinically benign lesions such as small fibroepithelial polyps, traumatic fibromas, or papillomas.

Step-by-Step Surgical Principles for Incisional Biopsy

1. Informed Consent: Detailed discussion of risks (bleeding, infection, pain, nerve injury, and potential scarring) and the diagnostic rationale.
2. Local Anaesthesia Technique: Deposit local anaesthetic solution peripherally as a field block or regional nerve block. Local anaesthetic solution must NEVER be injected directly into the body of the lesion, as direct intralesional injection causes severe tissue distension, hydrostatic ballooning, and cellular architectural artefacts (hydrodissection) that confound pathological interpretation.
3. Site Selection: Select an active, viable edge of the lesion. The biopsy wedge must incorporate both abnormal lesion tissue and adjacent clinically normal epithelium and submucosa to provide the pathologist with an intact transition margin.
4. Avoid Necrotic Centers: Never biopsy solely from the central slough or necrotic crater of an ulcer; necrotic tissue yields non-viable debris devoid of diagnostic cytological architecture.
5. Atraumatic Handling: Gently handle the specimen using fine tissue forceps or an atraumatic retraction suture placed through the edge. Avoid crushing the specimen with serrated tweezers, as crush artefact renders cellular morphology unreadable.
6. Geometry: Perform a deep, narrow, wedge-shaped (elliptical) incision extending through the full mucosal thickness into the underlying muscular or submucosal connective tissue to evaluate the depth of epithelial invasion.
7. Fixation: Place the specimen immediately into 10% neutral buffered formalin. The volume of formalin must be at least 10 to 20 times the volume of the tissue specimen to ensure rapid and uniform penetration. Never allow the tissue to dry out on gauze or immerse it in saline (which causes severe cellular autolysis).
8. Orientation & Requisition: For complex specimens, orient the tissue with a surgical suture tag (e.g., "short suture = superior; long suture = anterior"). Accompany the specimen with a comprehensive pathology requisition form detailing patient demographics, exact anatomical location, clinical history, provisional diagnosis, and a line drawing of the lesion.