Comprehensive Clinical Notes on Head and Neck Cancers

Management Philosophy and Multidisciplinary Care

Comprehensive Approach: Management of head and neck malignancy requires a multidisciplinary team to address the significant physical and functional morbidity of the disease.
Survival Metrics: Success is not measured solely by mortality rates; essential goals include the reduction of deformity and the restoration of physiologic function.
Quality of Life (QOL): Treatment evaluations must consider impacts on vision, smell, taste, hearing, air passage maintenance, and the ability to speak. The loss of speech significantly lowers QOL and alters lifestyle.
Patient Autonomy: Patients may intentionally choose treatment paths with slightly lower survival probabilities in exchange for better functional or cosmetic outcomes.
Core Team Members: Includes radiation oncologists, medical oncologists, dentists, maxillofacial prosthodontists, nutritionists, surgeons (head/neck, neuro, plastic, oral), pathologists, oncology nurses, radiologists, social workers, radiation therapists, speech therapists, and pain/neurology services.

Natural History and Epidemiology

Historical Impact: High-profile cases include Ulysses S. Grant (late 1800s), Sigmund Freud (malignancy spread through hard palate and sinuses), Sammy Davis Jr. (preferred keeping his voice over radical surgery), and Roger Ebert (mandible removal due to salivary gland cancer).
Celebrity Cases: Noted cases include Sean Connery, Michael Douglas, Elton John, Rod Stewart, and Eddie Van Halen.
General Statistics (NCI SEER 2023): * Estimated diagnosed (oral cavity/pharynx): $54,540$ * Estimated deaths: $11,580$ * Male incidence rates are more than twice as high as female rates.
2024 Estimates (Table 29.1): * Oral Cavity and Pharynx: $58,450$ new cases; $12,230$ deaths. * Larynx: $12,650$ new cases; $3,880$ deaths.
Viral Trends: Human Papillomavirus (HPV) related oropharyngeal cancers increased by $1.3\%$ annually in women and $2.8\%$ in men (2015–2019).
Race and Ethnicity Disparities: * $5$ -year survival (Oral Cavity/Pharynx): Whites at $66\%$ ; African Americans at $48\%$ . * Incidence decreased by over $2\%$ annually in African Americans (2005–2014) but increased by $1\%$ in Whites due to HPV.
Geographic Variation: * Nasopharyngeal Cancer (NPC) is endemic in Hong Kong, Southern China, Southeast Asia, Philippines, Malaysia, and Mediterranean/Eskimo populations. * Oral Squamous Cell Carcinoma (SCC) accounts for $50\%$ of all cancers in the Indian subcontinent due to betel nut (pan) chewing.

Metastatic Patterns and Field Cancerization

Distant Metastasis: The lungs are the most common site. Other sites include mediastinal lymph nodes, liver, brain, and bones.
Site Specificity: Distant metastasis incidence is highest in nasopharyngeal and hypopharyngeal tumors.
Predictors: There is a direct correlation between the bulk of cervical neck nodal disease and distant spread risk.
Direct Nerve Invasion: Tumors may spread along nerve routes (e.g., high-grade parotid tumors involving facial nerves causing paralysis).
Field Cancerization: Refers to the high risk of forming a second primary tumor (SPT) in the same anatomic field. * Lifetime risk of SPT: > $20\%$ . * SPTs are the leading cause of death in patients with early-stage head and neck tumors.

Etiology and Risk Factors

Tobacco and Alcohol: * Heaviest smokers/drinkers have a $35$ -fold increased risk for oral, oropharyngeal, hypopharyngeal, and laryngeal cancers. * Mortality from laryngeal cancer is $20$ times more likely in heavy smokers than non-smokers. * Synergistic effect: Ethanol suppresses DNA repair efficiency after exposure to nitrosamine compounds in tobacco.
Smokeless Tobacco: Contains potent noncombustible carcinogens like Nitrosamines ( $N$ -nitrosonornicotine). Associated with oral leukoplakia, gingival recession, and dental staining.
Occupational and Environmental: * Lip Cancer: Ultraviolet (UV) light exposure. * Larynx/Sinus: Furniture/woodworking (hardwood dust), nickel refining. * Steel/Textile: Oral cancer. * NPC: Dust, fumes, formaldehyde.
Radiation Exposure: Childhood exposure is linked to thyroid and salivary gland tumors (e.g., medical treatment for acne or tonsils; atomic bomb survivors).
Dietary Factors: * Plummer-Vinson Syndrome: Iron-deficiency anemia, esophageal webs, and glossitis; high incidence of postcricoid and tongue carcinoma. * Salted Fish: Ingestion since childhood (Southern China populations) linked to NPC due to dimethyl nitrosamine.
Genetics: * Bloom Syndrome: Rare autosomal recessive disorder; telangiectasia, photosensitivity; $150\text{ to }300$ times increased risk of malignancy. * Li-Fraumeni Syndrome: Autosomal dominant; germline mutations of the $p53$ tumor suppressor gene. * Mutation Accumulation: SCC requires $8\text{ to }11$ mutations; salivary gland malignancies require $4\text{ to }7$ .

Anatomy and Lymphatics

Vertebral Benchmarks: * $C1$ : Inferior margin of the nasopharynx. * $C2\text{–}C3$ : Oropharynx. * $C3$ : Level of the epiglottis. * $C4$ : True vocal cords.
Pharyngeal Divisions: * Nasopharynx: Posterior to nasal cavities, above soft palate. * Oropharynx: Behind the mouth, from soft palate to hyoid bone. * Hypopharynx (Laryngopharynx): Hyoid bone to esophagus.
Cranial Nerves (Functions): * $I$ (Olfactory): Smell. * $II$ (Optic): Sight. * $III$ (Oculomotor): Eye movement (up/down). * $IV$ (Trochlear): Eye movement (rotation). * $V$ (Trigeminal): Sensory face, motor jaw. * $VI$ (Abducens): Lateral eye movement. * $VII$ (Facial): Expressions, muscle contractions. * $VIII$ (Acoustic): Hearing. * $IX$ (Glossopharyngeal): Tongue/throat movement. * $X$ (Vagus): Talking/sounds. * $XI$ (Spinal Accessory): Shoulder/head movement. * $XII$ (Hypoglossal): Tongue movement, chewing.
Lymphatic Channels: Nearly one-third of the body's lymph nodes are in the head and neck. * Level I: Submental and submandibular. * Level II: Superior jugular (mandible to carotid bifurcation). * Level III: Middle jugular (carotid bulb to omohyoid). * Level IV: Lower jugular (omohyoid to clavicle). * Level V: Posterior triangle (spinal accessory chain). * Level VI: Anterior compartment (pretracheal/paratracheal). * Level VII: Upper mediastinal nodes. * Node of Rouvire: Lateral retropharyngeal node. * Jugulodigastric Node: Also called subdigastric node.

Clinical Presentation and Diagnostic Studies

Otalgia: Ear pain (cranial nerve $IX$ ) is reported by $60\%$ of patients; commonly referred from oropharyngeal cancer.
Clinical Signs by Site (Box 29.1): * Oral Cavity: Persistent ulcers/swelling. * Oropharynx: Dysphagia and otalgia. * Nasopharynx: Bloody discharge, hearing difficulty, high cervical mass. * Larynx: Hoarseness and stridor. * Hypopharynx: Painful neck node, dysphagia.
Standard Imaging: CT (bone invasion, deep invasion) and MRI (muscle invasion, cranial nerve involvement).
PET Imaging Subsets: * Hypoxia Specific: $F$ -fluoromisonidazole ( $F\text{-MISO}$ ). High tracer uptake/low perfusion predicts treatment failure. * Angiogenesis: $Zr$ -bevacizumab identifies Vascular Endothelial Growth Factor ( $VEGF$ ) levels.
Pathology: Over $80\%$ are SCC. Variants include lymphoepithelioma (better cure rates), spindle cell, and verrucous carcinoma.

General Treatment and Precision Techniques

Staging Update (8th TNM): HPV status is significant for oropharynx prognosis; includes "Depth of Invasion" for oral cavity and "Extranodal Extension" for nonviral-related mucosal HNC.
Surgery: * Radical Neck Dissection (RND): Removes Levels $I\text{–}V$ , sternocleidomastoid ( $SCM$ ) muscle, internal jugular ( $IJ$ ) vein, and cranial nerve $XI$ . * Modified RND: Spares $SCM$ , $IJ$ vein, or $CN\,XI$ if possible.
Chemotherapy: * Primary Agents: Cisplatin, $5$ -fluorouracil ( $5\text{-FU}$ ), methotrexate, taxanes. * Concurrent Chemoradiotherapy: Standard for advanced (Stage $III\text{/ }IV$ ) disease to improve survival.
Proton Beam RT (PBRT): Utilizes the Bragg peak for high dose delivery to the tumor while minimizing exit dose; ideal for re-irradiation.
Normal Tissue Complication Probability (QUANTEC): * Optic Nerve/Chiasm: Threshold < $5500\,cGy$ for toxicity. * Spinal Cord: Limit < $4500\text{ to }5000\,cGy$ to avoid myelopathy. * Parotid Gland: Mean dose should be < $2000\text{ to }2500\,cGy$ to preserve salivary function.

Site-Specific Radiation Therapy Strategies

Oral Cavity (Tongue/Floor): * Adjuvant dose: $64\text{ to }66\,Gy$ . * Gross disease: $70\,Gy$ . * Tongue cancers are high risk for contralateral lymph node involvement due to rich lymphatic intercommunication.
Nasopharynx: * Definitive dose: $7000\,cGy$ to Gross Tumor Volume ( $GTV$ ). * High-risk CTV: $5940\,cGy$ . * Low-risk CTV: $5000\text{ to }5400\,cGy$ . * Intracavitary boost often uses the Rotterdam nasopharynx applicator.
Larynx: * Glottic (T1/T2): Opposed lateral fields ( $5 \times 5\,cm$ to $6 \times 6\,cm$ ); dose $60\text{ to }70\,Gy$ . * Supraglottic: Requires larger volumes due to high nodal metastasis risk ( $40\text{ to }50\%$ ).
Salivary Glands: IMRT allows proximal nerve treatment to the brainstem with contralateral sparing. Postoperative dose: $60\text{ to }66\,Gy$ .

Management of Toxicities and Morbidity

Mucositis/Stomatitis: Occurs after $2000\text{ to }3000\,cGy$ . Epithelial sloughing causes friable ulcers.
Xerostomia: Scant/thick saliva starting at $1000\,cGy$ ; reduced long-term function at $2000\,cGy$ . Managed via Pilocarpine ( $Salagen$ ).
Periodontal Health: Teeth extractions must occur before RT to prevent osteoradionecrosis.
Nutrition: PEG tube placement is often prophylactic for concomitant chemoradiotherapy due to significant weight loss and mucositis.
Skin Care: Avoid alcohol-based products; use lukewarm water; Aquaphor/Eucerin for dry desquamation.
Lhermitte's Sign: Sensitivity occurring at $2000\text{ to }3000\,cGy$ .
Carotid Blowout Syndrome (CBOS): A fatal complication of re-irradiation where major branches of the carotid artery rupture. Risk is higher with SBRT if skin invasion is present.