Head & Neck Cancers
Surgery · Oncology · lean revision notes
Head & Neck Cancers
Head and neck cancer (HNC) is a heterogeneous group of malignancies arising from the mucosa of the oral cavity, pharynx, larynx, nose and paranasal sinuses, and the salivary glands. Over 90% are squamous cell carcinomas (SCC). This is a perennial favourite across Surgery, ENT and surgical oncology, with questions on tobacco/HPV aetiology, neck dissection nomenclature, reconstructive flaps, salivary gland tumours and TNM staging.
Definition & Scope
Head and neck cancers encompass tumours of:
- Oral cavity – lips, anterior 2/3 tongue, floor of mouth, buccal mucosa, gingiva, hard palate, retromolar trigone.
- Oropharynx – tonsil, base of tongue (posterior 1/3), soft palate, posterior pharyngeal wall.
- Hypopharynx – pyriform fossa (commonest), post-cricoid, posterior wall.
- Larynx – supraglottis, glottis, subglottis.
- Nasopharynx – distinct biology (EBV-driven).
- Nose & paranasal sinuses, and salivary glands.
High-yield: The single most common site of oral cavity cancer in India is the buccal mucosa / gingivo-buccal sulcus (because of pan/gutkha and tobacco quid chewing), whereas worldwide the lateral border of the tongue is the commonest oral subsite.
Etiology & Risk Factors
| Risk factor | Association / Comment |
|---|---|
| Tobacco (smoking + smokeless) | Most important; field cancerisation effect |
| Alcohol | Synergistic with tobacco (multiplicative risk) |
| Areca nut / betel quid | Oral submucous fibrosis → buccal SCC (India) |
| HPV-16 | Oropharyngeal (tonsil, base of tongue) SCC |
| EBV | Nasopharyngeal carcinoma |
| Sunlight (UV) | Lip carcinoma (lower lip) |
| Wood dust / nickel | Nasal & paranasal adenocarcinoma |
| Plummer–Vinson syndrome | Post-cricoid carcinoma in women |
| Chronic irritation, syphilis, poor oral hygiene | Oral SCC |
High-yield: HPV-positive oropharyngeal SCC occurs in younger, non-smoking patients, is p16-positive (IHC surrogate marker), presents commonly as a cystic neck node, and carries a markedly better prognosis than HPV-negative disease. It now has a separate AJCC 8th edition staging system.
Premalignant lesions (oral)
- Leukoplakia – white patch that cannot be wiped off and is not attributable to any other disease; ~5% malignant transformation. Speckled (erythroleukoplakia) has the highest risk.
- Erythroplakia – red velvety patch; highest malignant potential (carcinoma-in-situ in up to 90%).
- Oral submucous fibrosis – areca nut; trismus, blanched mucosa, leathery bands; premalignant.
High-yield: Erythroplakia > speckled leukoplakia > homogeneous leukoplakia in order of malignant potential. Biopsy any non-healing oral ulcer of >2–3 weeks.
Pathophysiology
Field cancerisation (Slaughter's concept) explains multifocal and second primary tumours: carcinogen exposure transforms the entire mucosal field, so the whole aerodigestive lining is at risk. Molecular progression involves loss of TP53, CDKN2A (p16), EGFR overexpression and, in HPV disease, viral E6/E7 oncoproteins inactivating p53 and Rb respectively (E6→p53 degradation; E7→Rb inactivation, leading to p16 over-expression as a surrogate marker).
Sequence: Normal mucosa → hyperplasia → dysplasia → carcinoma-in-situ → invasive SCC.
Clinical Features
By site:
- Oral cavity – non-healing indurated ulcer with raised everted edges, pain, bleeding, loose teeth, ill-fitting denture, referred ear pain (otalgia via lingual/auriculotemporal nerves), trismus (deep infiltration).
- Oropharynx – sore throat, dysphagia, otalgia, neck mass (often the first sign in HPV+ disease), muffled "hot potato" voice.
- Hypopharynx – progressive dysphagia, referred otalgia, hoarseness (late), neck node; poor prognosis (presents late, rich lymphatics).
- Larynx – glottic: early hoarseness (good prognosis, sparse lymphatics); supraglottic: throat pain, nodal spread early; subglottic: airway obstruction.
- Nasopharynx – neck node (commonest presentation), unilateral conductive deafness (Eustachian tube block → middle ear effusion), epistaxis, nasal obstruction, cranial nerve palsies (CN VI early).
High-yield: Trotter's triad of nasopharyngeal carcinoma = conductive deafness + ipsilateral immobility of soft palate + trigeminal (mandibular) neuralgia. An adult with unilateral serous otitis media must be evaluated for nasopharyngeal carcinoma.
Lymphatic Drainage & Neck Levels
The neck is divided into 6 levels (Robbins classification):
| Level | Region | Primary drainage |
|---|---|---|
| I | Submental (Ia), submandibular (Ib) | Lip, floor of mouth, oral cavity |
| II | Upper jugular | Oropharynx, oral cavity, larynx, parotid |
| III | Mid jugular | Larynx, hypopharynx, oral cavity |
| IV | Lower jugular | Hypopharynx, thyroid, cervical oesophagus |
| V | Posterior triangle | Nasopharynx, thyroid, scalp |
| VI | Central / anterior | Thyroid, glottis, subglottis, cervical oesophagus |
TNM Staging (AJCC 8th edition – key changes)
Two important 8th-edition refinements are heavily tested:
- Depth of invasion (DOI) is now incorporated into the T category of oral cavity cancer. DOI ≤5 mm, >5–10 mm, >10 mm upstage T.
- Extranodal extension (ENE) is now incorporated into the N category for HPV-negative disease (raises N stage; a major adverse prognostic factor).
- HPV/p16-positive oropharyngeal cancer has its own staging — far less stage migration, reflecting better prognosis.
| Feature | Why it matters |
|---|---|
| DOI | Predicts nodal metastasis & guides elective neck dissection (DOI >4 mm → high risk → treat the neck) |
| ENE | Strongest predictor of recurrence; indication for adjuvant chemoradiation |
| p16 status | Separates good vs poor prognosis oropharyngeal disease |
High-yield: In oral tongue SCC, depth of invasion >4 mm is the accepted cut-off to perform elective neck dissection even in a clinically node-negative (cN0) neck.
Diagnosis & Investigation of Choice
Stepwise workup: History & examination → examination under anaesthesia + panendoscopy (to detect synchronous second primary) → biopsy (incisional/punch) of the primary = gold standard for tissue diagnosis → imaging for staging → FNAC of neck node → p16/HPV and EBV testing as indicated.
- Biopsy of the primary – definitive diagnosis (incisional/punch for accessible mucosal lesions).
- Neck node – FNAC is the investigation of choice; avoid open excisional biopsy of a node before the primary is found (it can compromise later neck dissection and worsen outcome). If unknown primary, ipsilateral tonsillectomy + base-of-tongue mapping.
- Imaging – CECT (contrast CT) is the workhorse for assessing bone invasion (mandible) and nodal staging; MRI is superior for soft-tissue/tongue, perineural and skull-base extension (preferred in nasopharynx and tongue). PET-CT for unknown primary, distant metastasis, and post-treatment surveillance.
- OPG / orthopantomogram for mandibular involvement.
High-yield: Never do an open biopsy of a metastatic neck node as the first step — always seek the primary and use FNAC for the node. Open biopsy seeds the field and worsens prognosis.
Management
Treatment is multidisciplinary and stage-dependent.
- Early disease (Stage I–II): single modality — surgery OR radiotherapy. Oral cavity is usually treated by surgery; early glottic cancer by radiotherapy or transoral laser (voice preservation).
- Advanced disease (Stage III–IV): combined modality — surgery + adjuvant radiotherapy/chemoradiation, or definitive concurrent chemoradiotherapy (cisplatin-based) for organ preservation (e.g., larynx, hypopharynx).
- Adjuvant chemoradiation indications (post-op): positive margins and extranodal extension are the two strongest indications for adding cisplatin to radiotherapy.
Drugs
- Cisplatin – the backbone chemoradiotherapy agent (radiosensitiser).
- Cetuximab – anti-EGFR monoclonal; alternative when cisplatin is contraindicated.
- Pembrolizumab / nivolumab – PD-1 inhibitors for recurrent/metastatic disease.
High-yield: Concurrent cisplatin + radiotherapy is the standard organ-preservation strategy for advanced laryngeal and hypopharyngeal cancer (after the landmark VA larynx and RTOG 91-11 trials). Nasopharyngeal carcinoma is treated primarily by chemoradiotherapy, NOT surgery (radiosensitive, surgically inaccessible).
Neck Dissection — Classification (very high-yield)
| Type | Lymph node levels | Structures removed | Notes |
|---|---|---|---|
| Radical neck dissection (RND) | I–V | SCM + IJV + spinal accessory nerve (CN XI) | The "classic" Crile operation |
| Modified radical (MRND) | I–V (all 5) | Preserves ≥1 of the 3 (XI, IJV, SCM) | Type I: spares XI; Type II: XI+IJV; Type III (functional/Bocca): all three preserved |
| Selective neck dissection (SND) | Selected levels only | Preserves XI, IJV, SCM | e.g., supraomohyoid (I–III) for oral cavity; lateral (II–IV) for larynx/pharynx |
| Extended radical | I–V + additional | RND + extra nodes/structures (e.g., retropharyngeal, hypoglossal) |
High-yield: Radical neck dissection sacrifices three structures — SCM, internal jugular vein, and the spinal accessory nerve (CN XI). Sacrificing CN XI causes shoulder drop / winging and inability to abduct the arm above 90° (trapezius palsy). MRND preserves at least one; SND preserves all three and removes only at-risk levels.
Mnemonic — RND removes "IJV + SCM + XI": "I See eleven" (IJV, SCM, CN XI).
Reconstructive Flaps
After ablation, reconstruction restores form and function:
| Flap | Type | Typical use |
|---|---|---|
| Pectoralis major myocutaneous (PMMC) | Pedicled workhorse | Oral cavity/pharynx; reliable "workhorse" flap |
| Radial forearm free flap | Fasciocutaneous free | Thin pliable lining — tongue, floor of mouth |
| Fibula free flap | Osseocutaneous free | Mandibular reconstruction (bone + skin) |
| Anterolateral thigh (ALT) | Free | Bulky soft-tissue defects |
| Deltopectoral flap | Pedicled | Older; pharyngeal/skin defects |
High-yield: The PMMC flap (based on the pectoral branch of the thoraco-acromial artery) is the classic "workhorse" pedicled flap; the free fibula flap is the gold standard for segmental mandibular reconstruction.
Salivary Gland Tumours
About 80% are in the parotid; ~80% of parotid tumours are benign; ~80% of benign parotid tumours are pleomorphic adenoma (the "rule of 80s"). Conversely, the smaller the gland, the higher the chance of malignancy (sublingual/minor gland tumours are most often malignant).
| Tumour | Nature | Key features |
|---|---|---|
| Pleomorphic adenoma (benign mixed tumour) | Benign, commonest overall | Epithelial + myxoid/chondroid stroma; recurs if enucleated (pseudopod extensions); risk of malignant transformation (carcinoma ex-pleomorphic adenoma) |
| Warthin's tumour (papillary cystadenoma lymphomatosum) | Benign | Older men, smokers, can be bilateral; only tumour that is "hot" on technetium-99m pertechnetate scan; oncocytes + lymphoid stroma |
| Mucoepidermoid carcinoma | Most common malignant salivary tumour (and commonest in children) | Mucous + epidermoid cells; graded low to high |
| Adenoid cystic carcinoma | Malignant | Commonest malignancy of minor & submandibular glands; perineural invasion, cribriform "Swiss-cheese" pattern, late lung mets, relentless course |
| Acinic cell carcinoma | Low-grade malignant |
High-yield: Mucoepidermoid carcinoma = most common malignant salivary gland tumour. Adenoid cystic carcinoma = notorious for perineural spread, "Swiss-cheese/cribriform" histology and late distant metastasis. Warthin's tumour is the one that lights up on a pertechnetate scan and is associated with smoking and bilaterality.
Parotid surgery & facial nerve
- Investigation of choice for a parotid lump: FNAC (and MRI for deep-lobe/extent). Avoid incisional biopsy (risk of tumour seeding and facial nerve injury).
- Superficial parotidectomy with facial nerve preservation is standard for benign superficial-lobe tumours.
- Never enucleate a pleomorphic adenoma (high recurrence).
- A rapidly growing parotid mass with facial nerve palsy and fixed skin = malignancy until proven otherwise.
Complications
- Of disease: airway obstruction, dysphagia/aspiration, haemorrhage (carotid blow-out), local invasion (mandible, skull base), distant metastasis (lung commonest).
- Of surgery: facial nerve palsy (parotid), shoulder syndrome (CN XI), chyle leak (thoracic duct, left level IV), Frey's syndrome (gustatory sweating after parotidectomy — auriculotemporal nerve misdirection), flap necrosis.
- Of radiotherapy: xerostomia, mucositis, osteoradionecrosis of the mandible, hypothyroidism, dental caries, trismus, dysgeusia.
High-yield: Frey's syndrome (gustatory sweating/flushing over the cheek while eating) follows parotidectomy due to aberrant regeneration of parasympathetic auriculotemporal fibres into sweat glands. Diagnosed by Minor's starch–iodine test; treated with botulinum toxin or antiperspirants.
Key Differentials
- Neck mass in an adult: metastatic SCC node, lymphoma, tuberculous lymphadenitis, branchial cyst, carotid body tumour, thyroid swelling.
- Oral ulcer: traumatic/aphthous ulcer, tuberculous ulcer, syphilitic gumma, SCC.
- Parotid swelling: pleomorphic adenoma, Warthin's, sialadenitis, lymphoma, sarcoidosis (with sicca), parotid abscess.
- White oral patch: leukoplakia, lichen planus, candidiasis (wipes off), frictional keratosis.
High-yield: A lateral neck cystic mass in an adult > 40 years is metastatic (often HPV+ oropharyngeal SCC) until proven otherwise — not a branchial cyst. Do not treat as benign.
Recently asked / exam angle
- p16 immunohistochemistry as the surrogate marker for HPV-positive oropharyngeal SCC and its better prognosis (separate AJCC 8 staging).
- Depth of invasion now in T-staging of oral cancer; DOI >4 mm → elective neck dissection in cN0 neck.
- Extranodal extension (ENE) in AJCC 8 N-category and as an indication (with positive margins) for post-op concurrent cisplatin chemoradiation.
- Structures sacrificed in radical neck dissection (SCM, IJV, CN XI) — repeated single-best-answer.
- Most common malignant salivary tumour = mucoepidermoid carcinoma; perineural spread = adenoid cystic carcinoma.
- Warthin's tumour — bilateral, smokers, hot on pertechnetate scan.
- Trotter's triad and unilateral serous otitis media in adult → nasopharyngeal carcinoma.
- Frey's syndrome and Minor's starch–iodine test after parotidectomy.
- Nasopharyngeal carcinoma treated by chemoradiotherapy, not surgery; EBV association.
- Plummer–Vinson syndrome → post-cricoid carcinoma in women.
Rapid revision
- India's commonest oral cancer site = buccal mucosa/gingivobuccal sulcus (tobacco quid); worldwide = lateral tongue.
- Erythroplakia has the highest malignant potential among premalignant lesions.
- HPV-16 → oropharynx (tonsil/base of tongue), p16+, younger non-smokers, cystic node, better prognosis.
- EBV → nasopharyngeal carcinoma; presents with neck node + unilateral serous otitis media + epistaxis.
- Radical neck dissection removes SCM + IJV + spinal accessory nerve (CN XI) ("I See eleven").
- MRND preserves ≥1 of those three; selective dissection preserves all three and removes only at-risk levels.
- Supraomohyoid (levels I–III) dissection for oral cavity; lateral (II–IV) for larynx/pharynx.
- PMMC flap = workhorse pedicled flap; free fibula = mandibular reconstruction.
- Rule of 80s for parotid: 80% of salivary tumours parotid, 80% benign, 80% of those = pleomorphic adenoma.
- Mucoepidermoid carcinoma = commonest salivary malignancy; adenoid cystic = perineural spread + Swiss-cheese pattern; Warthin's = hot on pertechnetate, smokers, bilateral.
- FNAC is the investigation of choice for a neck node or parotid lump; never open-biopsy a metastatic node or parotid mass first.
- Positive margins + extranodal extension → add concurrent cisplatin chemoradiation; DOI >4 mm → elective neck dissection in cN0 neck.