Tongue carcinoma in detail, it’s ACJJ TNM classification , surgery etc according to standard ENT textbook for long answer in ENT pg exam

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Carcinoma of the Tongue

(Based on: Scott-Brown's Otorhinolaryngology Head & Neck Surgery; Cummings Otolaryngology Head and Neck Surgery; K J Lee's Essential Otolaryngology)

1. SURGICAL ANATOMY

The oral tongue (mobile tongue) is the anterior two-thirds of the tongue, demarcated from the base (posterior one-third) by the circumvallate papillae (vallate papillae). It is subdivided into:

Tip
Dorsum (specialized gustatory mucosa - thick keratinized epithelium)
Lateral borders (most common site of carcinoma)
Ventral surface (lining mucosa - non-keratinizing stratified squamous epithelium)

WHO classification: ICD-10 C02

Muscles:

Intrinsic: transverse, longitudinal, vertical
Extrinsic (4 paired): genioglossus, hyoglossus, styloglossus, palatoglossus
Motor innervation: hypoglossal nerve (CN XII) - except palatoglossus (vagus, CN X)

Sensory innervation:

General sensation: lingual nerve (branch of V3 - mandibular division of trigeminal)
Taste (anterior 2/3): chorda tympani (branch of facial nerve VII), running with the lingual nerve

Blood supply: Paired lingual arteries (3rd branch of external carotid artery). During posterior tongue resections, the contralateral vascular pedicle must be preserved to maintain the tongue tip.

Lymphatic drainage (clinically critical):

Lateral borders: drain ipsilaterally to cervical nodes (levels I-IV)
Midline, tip, and base of tongue: bilateral drainage - risk of contralateral node metastasis
Primary drainage: submandibular (level IB), upper jugular (level II), mid-jugular (level III)
Skip metastases to level IV are possible - hence neck dissection must include levels I-IV

2. EPIDEMIOLOGY

One of the most common oral cavity sites (22-39% of oral cancers) - second most common after the lip
Most tumours occur on the middle third, lateral border of the tongue (most common subsite)
Only 4-5% occur on the dorsum
Male predominance (slight); age at diagnosis: 6th-8th decade; 90% of patients are over 40 years
In populations with tobacco chewing habits, floor of mouth predominates
Increasing incidence in young patients (<40 years), possibly genetically susceptible, without obvious risk factors

3. AETIOLOGY AND RISK FACTORS

Factor	Details
Tobacco	Smoking and smokeless tobacco (gutkha, pan masala) - most significant
Alcohol	Synergistic with tobacco (risk multiplied, not additive)
Betel nut/pan	Common in South/Southeast Asia
Poor oral hygiene	Chronic dental trauma, ill-fitting dentures
HPV	HPV-16, HPV-18 (more significant for base of tongue/oropharynx)
Immunosuppression	Post-transplant, HIV
Pre-malignant lesions	Leukoplakia (1-17% risk), erythroplakia (>30% risk), submucous fibrosis

4. PREMALIGNANT CONDITIONS / LESIONS

Leukoplakia - white patch that cannot be scraped off; malignant transformation 1-17%
Erythroplakia - red velvety patch; most likely to be carcinoma or carcinoma in situ (~30%)
Submucous fibrosis - progressive fibrosis with limited mouth opening
Oral lichen planus - erosive type has some malignant potential

5. PATHOLOGY

Histological type: Squamous cell carcinoma (SCC) in >95% of cases

Gross morphology:

Exophytic / proliferative (better prognosis)
Ulcerative (most common presentation)
Infiltrative / endophytic (worst prognosis - tends to be deeper)

Histological grading (Broder's):

Grade I (well differentiated) - >75% keratin pearls, intercellular bridges
Grade II (moderately differentiated)
Grade III (poorly differentiated)
Grade IV (undifferentiated/anaplastic)

Histological malignancy grading (invasive front): Includes mode of invasion, lymphocytic response, perineural invasion, vascular invasion - more prognostically relevant than Broder's alone.

Depth of invasion (DOI): A critical prognostic parameter now incorporated into AJCC 8th edition T-staging. DOI is measured from the basement membrane of the adjacent normal mucosa to the deepest point of invasion (NOT the same as tumour thickness, which is measured from the surface).

6. CLINICAL FEATURES

Symptoms:

Non-healing painful ulcer on the tongue (most common)
Lump or swelling on the tongue
Pain - may radiate to the ear (otalgia via lingual nerve and auriculotemporal nerve - referred pain)
Dysphagia
Restricted tongue movement (tongue fixation) - indicates deep muscle invasion
Change in speech (dysarthria)
Hypersalivation
Cervical lymphadenopathy

Oral tongue vs. base of tongue at presentation:

Oral tongue: usually Stage I/II (symptomatic early)
Base of tongue: usually Stage III/IV (silent area, presents late)

Signs:

Ulcero-infiltrative lesion, most commonly lateral border of tongue
Induration around the ulcer
Fixation to floor of mouth or mandible in advanced disease
Ipsilateral cervical lymphadenopathy (21-34% at presentation)
Bilateral nodes in midline lesions

7. WORKUP AND INVESTIGATIONS

Clinical examination:

Full head and neck examination
Bimanual palpation of tongue, floor of mouth
CN VII, IX, X, XI, XII function assessment
Flexible nasolaryngoscopy (rule out synchronous primary, assess airway)

Biopsy: Incisional biopsy including deep margin (to assess DOI); punch biopsy or wedge biopsy under local anaesthesia

Imaging:

Investigation	Purpose
CT neck + chest with contrast	Assess primary tumour extent, bony erosion of mandible, cervical nodes, lung metastases
MRI of primary	Better soft tissue resolution; perineural invasion; DOI assessment
Intraoral ultrasound	Assessment of tumour thickness/DOI; guide neck dissection decision
PET-CT	Rule out distant metastases, detect occult nodes, follow-up
Orthopantomogram (OPG)/Panorex	Mandibular involvement
Chest X-ray	Baseline, lung metastasis

Panendoscopy (triple endoscopy): Direct laryngoscopy + oesophagoscopy + bronchoscopy - to rule out synchronous second primary tumours (field cancerization). Performed under GA.

Histopathology considerations:

Perineural invasion
Lymphovascular invasion
Depth of invasion
Margin status
Worst pattern of invasion

8. AJCC/TNM STAGING (8th Edition, 2017) - ORAL CAVITY

T Classification (Primary Tumour) - AJCC 8th Edition

Key change in AJCC 8th ed: Depth of Invasion (DOI) is now incorporated into T staging for oral cavity cancers.

T Stage	Criteria
TX	Primary tumour cannot be assessed
T0	No evidence of primary tumour
Tis	Carcinoma in situ
T1	Tumour ≤2 cm in greatest dimension AND DOI ≤5 mm
T2	Tumour ≤2 cm with DOI >5 mm and ≤10 mm OR tumour >2 cm but ≤4 cm with DOI ≤10 mm
T3	Tumour >4 cm OR any tumour with DOI >10 mm
T4a	Moderately advanced local disease - tumour invades adjacent structures: cortical bone of mandible or maxilla, maxillary sinus, or skin of face; OR extensive tumour with bilateral tongue involvement and/or DOI >20 mm
T4b	Very advanced local disease - invades masticator space, pterygoid plates, skull base, or encases the internal carotid artery

(Note: Extrinsic muscle invasion of tongue alone does not define T4a for oral tongue; bone invasion, skin involvement, or maxillary sinus involvement does)

N Classification (Regional Lymph Nodes) - AJCC 8th Edition

Key change: Extranodal extension (ENE) is now incorporated into N staging.

N Stage	Criteria
NX	Regional nodes cannot be assessed
N0	No regional node metastasis
N1	Single ipsilateral node, <3 cm, ENE-negative
N2a	Single ipsilateral node, <3 cm, ENE-positive OR single ipsilateral node >3 cm but <6 cm, ENE-negative
N2b	Multiple ipsilateral nodes, all <6 cm, ENE-negative
N2c	Bilateral or contralateral nodes, all <6 cm, ENE-negative
N3a	Any node >6 cm, ENE-negative
N3b	Single ipsilateral node >3 cm ENE-positive; OR multiple ipsilateral/contralateral/bilateral nodes with any ENE-positive

M Classification (Distant Metastasis)

M Stage	Criteria
M0	No distant metastasis
M1	Distant metastasis present (most common: lungs > liver > bone)

Overall Stage Grouping

Stage	T	N	M
0	Tis	N0	M0
I	T1	N0	M0
II	T2	N0	M0
III	T3	N0	M0
III	T1-T3	N1	M0
IVA	T4a	N0-N1	M0
IVA	T1-T4a	N2	M0
IVB	Any T	N3	M0
IVB	T4b	Any N	M0
IVC	Any T	Any N	M1

9. TREATMENT

General Principles

Surgery is the primary treatment for most oral tongue cancers
Combined modality treatment (surgery + radiotherapy) for advanced disease
1 cm clear margin in three dimensions is the goal for surgical resection
Depth of invasion guides management of the neck

A. MANAGEMENT OF PRIMARY TUMOUR

Early Disease (T1-T2)

Partial glossectomy (hemiglossectomy) for lateral border lesions
Aim: resect with ≥1 cm margin in all three dimensions
Compartmental resection (as in musculoskeletal oncology) improves outcomes
Intraoperative ultrasound to assess deep margin
Reconstruction:
- Small defects (<30%): primary closure or healing by secondary intention
- Medium defects: skin graft (STSG), local flap (buccal advancement)
- Large defects (>50% tongue): free flap reconstruction (radial forearm free flap - RFFF - is the workhorse; thin, pliable, allows good tongue mobility)

Advanced Disease (T3-T4)

Near-total or total glossectomy may be required
Associated laryngectomy may be needed if aspiration risk is high
Total glossectomy without laryngectomy is possible in selected patients
Composite resection (commando operation) if mandible involved:
- Includes glossectomy + partial mandibulectomy + ipsilateral neck dissection
- Approached through lip-splitting incision with mandibulotomy (paramedian, step/stair-step cut)

Mandibular Involvement

Extent of Invasion	Procedure
Periosteum only	Subperiosteal resection with periosteum, mandible preserved
Periosteum invaded	Marginal (rim) mandibulectomy - removes superior aspect, maintains mandibular continuity
Medullary/cortical bone invasion	Segmental mandibulectomy - removes full thickness segment

Marginal mandibulectomy is contraindicated in very atrophic mandibles (risk of pathological fracture) and radiation-damaged bone
Segmental defects reconstructed with fibula osteocutaneous free flap (gold standard) or iliac crest/scapula free flap
Titanium plates used as bridging in select cases

Radiotherapy as Definitive Treatment

For patients unfit for surgery
External beam radiotherapy (EBRT) ± brachytherapy (interstitial implants)
T1/T2 lesions: comparable local control rates to surgery
Brachytherapy alone gives excellent results for small (<3 cm) tongue tumours

B. MANAGEMENT OF THE NECK

Elective neck dissection (END) is indicated when the risk of occult nodal metastasis exceeds 20%:

All T2 and above lesions
T1 lesions with DOI >4 mm (high risk)
DOI is the strongest predictor of occult nodal disease

Extent of neck dissection:

Selective neck dissection (SND) - levels I-IV is the standard for tongue carcinoma (level IV included because of skip metastases)
Modified radical neck dissection (MRND - type I, II, or III) for N+ necks (sparing non-nodal structures)
Radical neck dissection (RND) only if internal jugular vein, SCM, or spinal accessory nerve are encased by tumour

Bilateral neck dissection indicated for:

Midline tongue lesions
Lesions crossing the midline
Tip of tongue tumours
Up to 4.5% have contralateral occult disease

Sentinel lymph node biopsy (SLNB):

Emerging role in clinically N0 (cN0) tongue cancer T1-T2
Negative SLNB can potentially avoid formal neck dissection
Not yet universally adopted as standard of care

C. POST-OPERATIVE RADIOTHERAPY (PORT)

Indications for PORT (adjuvant radiotherapy after surgery):

Positive or close margins (<5 mm)
Multiple positive cervical nodes
Extracapsular spread (ECS) in cervical nodes
Perineural invasion
Lymphovascular invasion
T3/T4 primary
Tumour thickness >9-10 mm even without other adverse features

PORT dose: 60-66 Gy in 30-33 fractions over 6-7 weeks

Concurrent cisplatin-based chemotherapy added for ECS or positive margins (high-risk features) - per RTOG 9501 / EORTC 22931 trials

D. RECONSTRUCTION PRINCIPLES

Goal: Maximize function of residual tongue tissue (mastication, deglutition, speech)

Defect	Reconstruction
<30% tongue	Primary closure / secondary intention
30-50% tongue	Split thickness skin graft (STSG) / local flap
>50% tongue (hemi- to subtotal)	Radial forearm free flap (RFFF) - workhorse: thin, pliable, sensate
Total glossectomy	Anterolateral thigh (ALT) free flap; RFFF
With mandibular segment	Fibula osteocutaneous free flap

Preserve tip of tongue whenever possible - tip preservation maximizes speech and swallowing
Monopolar electrocautery can cause tissue damage and should be used cautiously near neurovascular structures

10. TREATMENT SUMMARY BY STAGE

Stage	Primary Treatment	Neck
T1N0 (DOI ≤5 mm)	Partial glossectomy	Observation or SLNB
T1-T2 N0 (DOI >4-5 mm)	Partial glossectomy	Elective SND levels I-IV
T2-T3 N0	Glossectomy (partial/subtotal)	Elective SND I-IV ± PORT
T1-T3 N+	Glossectomy + PORT ± chemo	Therapeutic MRND/RND + PORT
T4a	Total/near-total glossectomy ± mandibulectomy	MRND + PORT + chemo
T4b (unresectable)	Concurrent chemoradiation (definitive CRT)	-

11. PROGNOSIS

Overall 5-year survival:

Stage I: ~80-85%
Stage II: ~65-75%
Stage III: ~40-60%
Stage IV: ~20-40%

Poor prognostic factors:

Advanced T stage (T3/T4)
Cervical lymph node metastasis
Extracapsular spread (ECS) - single most important poor prognostic factor for regional disease
Multiple positive nodes
Perineural invasion
Tumour thickness >9-10 mm (5-year survival 66% vs. 100% for <3 mm tumours)
Positive surgical margins
DOI >20 mm
Young patients (<40 years) - paradoxically worse prognosis despite no risk factors

Recurrence:

Rate: 10-50%
Usually locoregional
Most within first 2 years
Metachronous second primary tumours in ~10% (field cancerization)

12. BASE OF TONGUE CARCINOMA (Brief Note)

Classified as oropharyngeal carcinoma (not oral cavity) - different AJCC staging applies
Presents late (Stage III/IV) due to silent location
Strong association with HPV-16 in younger patients (better prognosis)
Primary nodal drainage: levels II-IV bilaterally
Treatment: chemoradiation preferred (to preserve swallowing function)
Surgery (transoral robotic surgery - TORS) gaining favour for selected cases

KEY POINTS FOR PG EXAM (Mnemonics and High-Yield Facts)

Most common site: Lateral border, middle third of oral tongue
AJCC 8th ed change: DOI incorporated into T staging + ENE incorporated into N staging
T1: ≤2 cm AND DOI ≤5 mm (both must be satisfied)
T3: >4 cm OR DOI >10 mm (either is sufficient)
Neck dissection threshold: DOI >4 mm or >20% risk of occult nodes
Levels for tongue: I-IV (not just I-III, because of skip mets to level IV)
Bilateral neck treatment: for midline, tip, or crossing-midline lesions
Worst prognosis feature: Extracapsular spread (ECS) - mandates PORT + concurrent cisplatin
PORT double-dose consideration: Tongue PORT doses higher than floor of mouth
Reconstruction workhorse: Radial forearm free flap (RFFF) for hemiglosssectomy defects; fibula free flap if mandible resected
Commando operation: Total glossectomy + ipsilateral total mandibulectomy + radical neck dissection (combined resection for advanced disease)
Referred otalgia: Via lingual nerve (V3) - explains ear pain with tongue cancer
Occult nodal disease: Up to 53% of clinically N0 tongue cancers have occult nodes
Erythroplakia: Most dangerous premalignant lesion (>30% are already carcinoma)

Sources: Scott-Brown's Otorhinolaryngology Head & Neck Surgery (9th ed); Cummings Otolaryngology Head and Neck Surgery (7th ed); K J Lee's Essential Otolaryngology (11th ed); AJCC Cancer Staging Manual, 8th Edition (2017)

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