11.1 Premalignant Lesions & Oral Cancer
Key Takeaways
- NICE NG12 requires a suspected cancer pathway referral (2-week wait) for any unexplained oral ulceration lasting more than 3 weeks, and for persistent unexplained red/red-white patches or neck lumps
- Erythroplakia has the highest malignant transformation of any oral potentially malignant disorder (around 30–50% in meta-analyses, with ~40% already invasive at first biopsy)
- Oral epithelial dysplasia is graded mild, moderate or severe using both architectural and cytological atypia; severe dysplasia involving the full epithelial thickness is carcinoma in situ
- In the UK the lateral border of the tongue is the most common intra-oral site for OSCC, followed by the floor of mouth
- The 8th edition AJCC/UICC TNM staging for oral cavity cancer incorporates depth of invasion (DOI) in addition to maximum tumour diameter
Oral Potentially Malignant Disorders (OPMDs)
An oral potentially malignant disorder (OPMD) is a mucosal disorder in which an increased risk of oral squamous cell carcinoma (OSCC) exists compared with normal mucosa. MFDS Part 1 expects you to recognise the common OPMDs, grade dysplasia, and quote approximate malignant transformation (MT) rates.
Oral Epithelial Dysplasia
Dysplasia is the abnormal maturation of the epithelium graded on combined architectural and cytological atypia (the WHO three-tier system remains in routine UK use).
| Grade | Architectural features | Cytological features | Approx MT risk |
|---|---|---|---|
| Mild | Basal cell hyperplasia | Atypia confined to lower third | ~7% |
| Moderate | Drop-shaped rete ridges | Atypia into middle third | ~11% |
| Severe | Loss of stratification, keratin pearls | Atypia into upper third, pleomorphism, hyperchromasia | ~17% |
Carcinoma in situ = severe dysplasia involving the full epithelial thickness without breach of the basement membrane. Once the basement membrane is breached, the lesion is invasive carcinoma.
Leukoplakia
Leukoplakia is a white plaque that cannot be rubbed off and cannot be characterised as any other diagnosable disease. Two clinical subtypes:
- Homogeneous — flat, uniform white plaque, lower MT risk.
- Non-homogeneous — speckled, nodular, verrucous; higher MT risk.
Proliferative verrucous leukoplakia (PVL) is a rare, multifocal, recurrent, slow-growing verrucous white lesion with a markedly high MT rate (around 50% in case series) — managed in an oral medicine / head and neck MDT setting.
Erythroplakia
Erythroplakia is a fiery red, velvety patch that cannot be attributed to another diagnosis. It has the highest MT rate of any OPMD — meta-analyses report around 30–50%, and roughly 40% of lesions are already invasive carcinoma at first biopsy. Erythroplakia mandates urgent biopsy.
Other OPMDs
- Oral submucous fibrosis (OSMF) — caused by areca/betel nut chewing; progressive submucosal fibrosis produces restricted mouth opening and palpable fibrous bands; MT around 5%.
- Oral lichen planus — reticular (Wickham striae), atrophic, erosive forms; erosive/atrophic variants carry higher risk; overall MT around 1%.
- Actinic keratosis (actinic cheilitis) — lower lip of outdoor workers from chronic UV exposure; can progress to SCC of the lip.
MFDS clinical rule: Red patch, non-homogeneous white patch, ulcer lasting >3 weeks, or persistent lump — biopsy or refer under the suspected cancer pathway. Do not reassure.
A 60-year-old male smoker has a 2 cm fiery red, velvety, asymptomatic patch on the soft palate that has been present for 8 weeks. Biopsy is reported as 'severe dysplasia with focal full-thickness atypia but no basement membrane breach'. Which statement is most accurate?
A 42-year-old man who chews betel quid daily presents with progressive restriction of mouth opening (currently 22 mm interincisal) and palpable fibrous bands in the buccal mucosa. The mucosa is pale and stiff. What is the most likely diagnosis?
Oral Squamous Cell Carcinoma (OSCC)
Oral squamous cell carcinoma (OSCC) accounts for more than 90% of oral malignancies. UK incidence is around 3,700 new mouth cancer cases per year (Cancer Research UK), with a ~2:1 male predominance and peak age 66–70 years. Incidence is rising, partly attributable to HPV-related oropharyngeal disease and continuing tobacco/alcohol use.
Risk Factors
| Factor | Notes |
|---|---|
| Tobacco | Smoked and smokeless; dose-dependent |
| Alcohol | Synergistic with tobacco; >35 units/week markedly increases risk |
| Betel quid / areca nut / gutka | Independent and synergistic; high in South Asian populations |
| HPV (mainly HPV16) | Oropharyngeal site (base of tongue, tonsil); better prognosis than tobacco-driven OSCC |
| Immunosuppression | Organ transplant, HIV |
| Field cancerisation | Synchronous / metachronous lesions |
Common Intra-oral Sites (UK)
| Site (ICD-10) | Approx. proportion |
|---|---|
| Lateral/ventral tongue (C02) | ~33% |
| Floor of mouth (C04) | ~13% |
| Base of tongue (C01, oropharynx) | ~12% |
| Palate, gingiva, buccal mucosa | remainder |
In betel-quid chewers the buccal mucosa is disproportionately affected.
TNM Staging (8th edition AJCC / UICC)
| T | Criteria |
|---|---|
| T1 | Tumour ≤2 cm AND depth of invasion (DOI) ≤5 mm |
| T2 | Tumour ≤2 cm with DOI >5 mm, OR 2–4 cm with DOI ≤10 mm |
| T3 | Tumour >4 cm OR any DOI >10 mm |
| T4 | Invasion of adjacent structures (cortical bone, deep tongue muscles, skin, masticator space) |
The 8th edition added depth of invasion (DOI) because it predicts nodal metastasis and survival better than diameter alone. N staging uses levels I–V (I submental/submandibular, II upper jugular, III mid-jugular, IV lower jugular, V posterior triangle). DOI also feeds into N classification for HPV-positive vs HPV-negative disease.
NICE NG12 Referral Pathway
NICE guideline NG12 (Suspected cancer: recognition and referral) recommends:
- Suspected cancer pathway referral (2-week wait) for oral cancer in people with unexplained ulceration of the oral cavity lasting more than 3 weeks, or a persistent unexplained lump in the neck.
- Dentists assessing a lump on the lip or in the oral cavity, or a red / red-and-white patch consistent with erythroplakia or erythroroleukoplakia, should refer under the suspected cancer pathway.
The 4-warning-sign mnemonic taught in UK dental schools is red, white, ulcer, lump: any persistent red patch, non-homogeneous white patch, ulcer >3 weeks, or unexplained lump warrants referral.
Management Principles
- Incisional biopsy (or punch biopsy) for histological diagnosis — never excise an undiagnosed oral lesion in primary care.
- Staging imaging — MRI for soft tissue extent, CT for bone, USS ± FNA for neck nodes; FDG-PET-CT in selected cases.
- MDT in a designated head and neck cancer centre.
- Surgery with clear margins; neck dissection for nodal disease (selective or modified radical depending on staging).
- (Chemo)radiotherapy — adjuvant or primary depending on site, stage, and patient fitness.
- Reconstruction — local flaps, free flaps, obturators as appropriate.
Screening
There is no UK population screening programme for oral cancer; opportunistic screening at routine dental examination is the current model. Mortality benefit of formal screening has not been demonstrated in randomised trials, so the focus is on early recognition and referral of symptomatic or suspicious lesions.
A 55-year-old male smoker presents in primary dental care with a 1.5 cm ulcer on the lateral border of the tongue that has been present for 4 weeks. It is not painful and he cannot recall trauma. What is the most appropriate management?
According to the 8th edition AJCC/UICC TNM staging for oral cavity squamous cell carcinoma, which feature defines T2 disease?
Which anatomical site is the most common intra-oral location for oral squamous cell carcinoma in the UK?