Laryngeal Cancer

Laryngeal cancer is a malignancy arising from the epithelial lining of the larynx, representing approximately 2-3% of all human cancers and roughly 25-30% of all head and neck malignancies. The vast majority (>95%) of laryngeal cancers are squamous cell carcinomas (SCCs), arising from the stratified squamous epithelium lining the vocal cords, false vocal cords, aryepiglottic folds, and anterior/posterior commissure. Incidence peaks in the 6th-7th decade of life with a strong male predominance (4:1 ratio), though this gap is narrowing due to increasing tobacco and alcohol use among women. Understanding laryngeal cancer epidemiology, pathophysiology, and multidisciplinary management is essential for clinical practice, as early detection dramatically improves prognosis and voice preservation outcomes. The disease carries significant morbidity related to voice loss and swallowing dysfunction, making treatment decisions highly dependent on tumor stage, location, and patient factors.

Laryngeal cancer develops through a well-characterized multi-step process of field cancerization, wherein cumulative genetic alterations in epithelial cells progressively accumulate due to chronic carcinogen exposure. The classical model involves sequential transformation: normal epithelium → dysplasia (mild, moderate, severe) → carcinoma in situ → invasive squamous cell carcinoma. Tobacco smoke and alcohol independently cause direct DNA damage through carcinogenic metabolites (polycyclic aromatic hydrocarbons, nitrosamines) that form DNA adducts, overwhelm repair mechanisms, and induce p53 and RB pathway inactivation. The TP53 tumor suppressor gene is mutated in >50% of laryngeal SCCs, abolishing G1/S checkpoint control and allowing uncontrolled proliferation. CDKN2A (p16) inactivation occurs through deletion or methylation in 30-40% of cases, eliminating the RB pathway brake. In HPV-positive laryngeal cancers (approximately 5-15% of cases, higher in non-smokers), E6 and E7 viral oncoproteins directly inactivate p53 and RB respectively, bypassing the need for multiple independent mutations and creating a distinct molecular subtype with potential therapeutic implications.

The EGFR (epidermal growth factor receptor) is overexpressed in >90% of laryngeal SCCs through gene amplification, transcriptional upregulation, or increased ligand availability. Activated EGFR stimulates the RAS/RAF/MEK/ERK pathway and PI3K/AKT/mTOR pathway, driving proliferation, survival, angiogenesis, and invasion. This pathway hyperactivation is partially independent of mutational status, as wild-type EGFR signaling alone provides sufficient oncogenic stimulus in the context of p53/RB loss. EGFR expression levels correlate with aggressive phenotype and poor prognosis, providing rationale for targeted monoclonal antibody therapy (cetuximab) in advanced disease.

Tumor-associated hypoxia drives HIF-1α (hypoxia-inducible factor-1α) stabilization, which transactivates VEGF (vascular endothelial growth factor) and other pro-angiogenic factors, creating a permissive microenvironment for invasion and metastasis. Simultaneously, dysregulated TGF-β signaling, loss of E-cadherin expression, and increased Snail/Slug transcription factors orchestrate EMT, wherein epithelial cells acquire mesenchymal characteristics (reduced cell-cell adhesion, increased motility, enhanced invasiveness). The cancer-associated fibroblasts (CAFs) within the tumor microenvironment further promote invasion through production of matrix metalloproteinases (MMPs), particularly MMP-2 and MMP-9, which degrade the extracellular matrix and basement membrane, facilitating stromal invasion and lymph node metastasis.

Laryngeal SCCs exploit multiple immune evasion mechanisms: downregulation of MHC Class I expression limits T-cell recognition; production of immunosuppressive cytokines (TGF-β, IL-10) and recruitment of regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs) create an immunologically permissive microenvironment; and PD-L1 (programmed death ligand-1) expression on tumor cells and infiltrating immune cells engages PD-1 receptors on T cells, delivering inhibitory signals that exhaust anti-tumor immunity. This explains the rationale for immune checkpoint inhibition in advanced disease.

Alcohol (ethanol) metabolism generates acetaldehyde, a known carcinogen that forms DNA-protein crosslinks, induces reactive oxygen species (ROS), and causes chronic inflammation. Polymorphisms in alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) genes modify individual susceptibility; individuals with ADH1B*2 allele (rapid ethanol oxidation) and ALDH2*1 allele (slow acetaldehyde metabolism) experience higher acetaldehyde exposure and increased cancer risk. Chronic inflammation from tobacco and alcohol exposure upregulates cyclooxygenase-2 (COX-2) and NF-κB signaling, perpetuating a pro-tumoral inflammatory state. Laryngeal cancers often demonstrate altered Wnt/β-catenin signaling through APC mutations or increased Wnt ligand expression, promoting stemness and chemotherapy resistance.

Cigarette smoking is the single most significant modifiable risk factor, accounting for approximately 70-80% of laryngeal cancer cases. The dose-response relationship is profound: individuals smoking ≥1 pack daily have 20-40 times the risk compared to never-smokers. The carcinogenic effect correlates with duration of exposure, intensity, and degree of inhalation, with cumulative pack-years serving as a useful quantitative metric. Former smokers retain elevated risk for decades, though the rate of decline in risk over time is slower for laryngeal cancer than for lung cancer, suggesting that field cancerization changes persist. Cigar and pipe smoking carries similar risk to cigarettes when considering total tobacco burden.

Alcohol consumption, particularly heavy daily intake (≥4 drinks/day), independently elevates laryngeal cancer risk by 2-10 fold depending on consumption level. The mechanism is dose-dependent and non-linear; the risk accelerates substantially above 50 grams of alcohol daily (approximately 3-4 standard drinks). Alcohol likely acts both through direct carcinogenic metabolites (acetaldehyde) and indirectly through nutritional deficiencies, impaired DNA repair, and enhanced susceptibility to HPV infection. Critically, tobacco and alcohol demonstrate synergistic interaction; concurrent smoking and heavy drinking increases risk 15-30 fold compared to either exposure alone, suggesting additive or multiplicative carcinogenic mechanisms.

HPV infection, particularly HPV-16 and HPV-18 high-risk types, is an independent risk factor accounting for 5-15% of laryngeal cancers with increasing prevalence trends. HPV-positive laryngeal cancers typically occur in non-smokers and non-drinkers, arise more commonly from the posterior larynx and oropharynx, and exhibit distinct molecular characteristics (wild-type TP53, elevated p16 expression). These tumors often present at more advanced stages but paradoxically carry better prognosis compared to HPV-negative, tobacco/alcohol-related cancers, likely due to enhanced immunogenicity and greater chemotherapy sensitivity. HPV vaccination impact on laryngeal cancer prevention is not yet fully characterized given the recent implementation of broad HPV vaccination programs.

Male predominance (4:1) reflects higher historical rates of tobacco and alcohol use in men, though this epidemiologic gap is narrowing. Women developing laryngeal cancer tend to be diagnosed at older ages and earlier stages compared to men, possibly due to greater awareness of voice changes. Post-menopausal hormonal status may confer some increased susceptibility, though this remains incompletely understood.

Peak incidence occurs between 60-75 years, reflecting cumulative carcinogen exposure over decades. Laryngeal cancer is exceptionally rare in patients <40 years unless significant risk factors (heavy smoking/drinking, HPV infection) are present.

Chronic laryngopharyngeal reflux (LPRD) causing repeated epithelial injury and chronic inflammation may promote carcinogenesis, though causality remains contested. The irritative effects of recurrent reflux acid exposure may act synergistically with tobacco/alcohol exposure. Similarly, chronic environmental irritants (occupational dust, chemical inhalation) and vocal trauma from occupational voice abuse have been implicated, though evidence is less robust than for tobacco and alcohol.

Fanconi anemia, xeroderma pigmentosum, and other inherited DNA repair disorders carry increased laryngeal cancer risk. First-degree relatives of laryngeal cancer patients show modestly elevated risk, suggesting both genetic and shared environmental factors contribute. Polymorphisms in glutathione S-transferase (GST) and cytochrome P450 genes influencing carcinogen metabolism may modify individual susceptibility.

Patients with prior history of laryngeal cancer face substantially elevated risk of second primary malignancies in the larynx, pharynx, or lung (10-15% at 5 years), reflecting ongoing field cancerization in at-risk epithelium.

Hoarseness is the most common presenting symptom, occurring in >75% of laryngeal cancer patients. The pathophysiologic basis depends on tumor location: glottic cancers (70% of all laryngeal cancers) directly affect vocal cord function through mass effect, preventing complete cord approximation or causing asymmetric vibration, resulting in breathy, rough, or strained voice quality. Hoarseness of >2-3 weeks duration warrants laryngeal evaluation, particularly in smokers/heavy drinkers; any adult with persistent hoarseness should be presumed to have laryngeal pathology until proven otherwise (this high-yield concept is frequently tested). The degree of hoarseness correlates imperfectly with tumor size; small glottic lesions may cause disproportionate voice changes due to their impact on the vibrating margin, while larger supraglottic tumors may cause minimal dysphonia initially.

Throat pain (pharyngalgia) occurs in 25-40% of cases and may be insidious or acute. The pain is typically ipsilateral to the tumor and may worsen with swallowing (odynophagia), eating, or voice use. Referred otalgia (ear pain) occurs in 15-25% of cases due to shared innervation via the vagus nerve (CN X) and glossopharyngeal nerve (CN IX); importantly, otolaryngology dogma teaches that any patient presenting with ear pain without corresponding otologic pathology should raise suspicion for laryngeal pathology (Costen's syndrome and temporomandibular joint dysfunction are far more common, but laryngeal cancer must not be missed). Pain suggests more advanced disease, potential arytenoid involvement, or cartilage invasion.

Difficulty or discomfort with swallowing occurs in 20-30% of cases and typically indicates more advanced disease. Supraglottic cancers are more likely to cause dysphagia due to their anatomic proximity to the pharynx and potential for epiglottic involvement affecting the protective mechanism during swallowing. Patients may report sensation of "something in the throat," progressive difficulty with solid foods, or symptoms worse with liquid intake (suggesting aspiration risk). Severe dysphagia warrants assessment of aspiration risk and may necessitate modified diet or swallowing intervention.

Breathing difficulty or audible breathing sounds (stridor) suggest advanced disease with airway compromise. Inspiratory stridor (louder during inhalation) indicates laryngeal obstruction; biphasic stridor suggests fixed obstruction. This symptom is ominous and may necessitate urgent airway management considerations. Dyspnea at presentation occurs in <10% of cases, often indicating extensive disease or bilateral involvement.

Hemoptysis (spitting up blood or blood-tinged saliva) occurs in 5-15% of cases and represents mucosal ulceration or invasion of laryngeal vasculature. This symptom frequently prompts patient concern and medical evaluation.

Unintentional weight loss reflects difficulty with eating (dysphagia), increased metabolic demands from malignancy, and systemic inflammatory effects. Weight loss >5% over 3 months suggests more advanced disease. Fatigue and general malaise are less specific but occur with advanced disease.

Laryngeal Examination: Direct or indirect laryngoscopy reveals the gross appearance of laryngeal lesions. Glottic tumors typically appear as irregular, friable masses with variable color (red, white, ulcerated); the lesion may be polypoid, sessile, or infiltrative. Subglottic involvement may not be visible without careful examination of the anterior commissure and anterior laryngeal surface. Supraglottic lesions may be difficult to visualize with indirect laryngoscopy, requiring flexible fiberoptic evaluation. The cardinal finding is any unexplained laryngeal mass with irregular surface, abnormal vasculature, or fixation of vocal cords.

Vocal Cord Mobility: Assess during phonation and quiet respiration. Fixed vocal cord(s) indicate invasion of the cricoarytenoid joint, interarytenoid muscles, or recurrent laryngeal nerve; this finding significantly impacts staging (T3 or T4) and prognosis. Asymmetric vocal cord position or impaired abduction suggests nerve involvement.

Cervical Lymphadenopathy: Palpation of the neck for firm, fixed lymph nodes suggests cervical metastases. Laryngeal SCCs commonly metastasize to ipsilateral cervical lymph nodes (80% for advanced T3-T4 disease); presence of cervical nodes upstages disease and influences treatment decisions. Nodes should be characterized as mobile vs. fixed and measured.

Indirect Physical Findings: Fever or systemically ill appearance suggests advanced disease or infection. Examination for Horner syndrome (miosis, ptosis, anhidrosis) may indicate invasion into the sympathetic chain from advanced tumors. Assessment for cranial nerve deficits (particularly CN X, XI, XII) suggests skull base or lower cervical involvement.

Glottic vs. Supraglottic Presentation: Glottic cancers typically present early with voice changes (T1-T2 disease in >75% at diagnosis), resulting in better prognosis. Supraglottic cancers often present with throat pain, dysphagia, or cervical adenopathy and are frequently diagnosed at advanced stages (T3-T4 in 50% of cases). Subglottic cancers are the rarest subsite and often detected late.

Occult Metastatic Disease: Approximately 10-15% of newly diagnosed laryngeal cancer patients have clinically occult distant metastases, most commonly to lung and liver. Constitutional symptoms or imaging findings may hint at metastatic disease.

A thorough history focusing on duration and character of hoarseness, smoking and alcohol consumption (quantified in pack-years and drinks per week/day), associated symptoms (dysphagia, dyspnea, otalgia, weight loss), and prior head and neck malignancies is essential. The 2-3 week rule is critical: any hoarseness lasting longer than 2-3 weeks in a smoker or significant alcohol user warrants laryngeal visualization. Prior radiation to the head and neck increases risk of secondary laryngeal cancer years to decades later.

Visual examination of the larynx is mandatory for diagnosis. Indirect laryngoscopy using a mirror can be performed in office but has limited sensitivity in detecting small lesions or supraglottic pathology. Flexible fiberoptic laryngoscopy is the gold standard office procedure: allows superior visualization of all laryngeal subsites, permits assessment of vocal cord mobility during phonation and respiration, enables identification of mass characteristics (size, surface texture, vascularity, ulceration), and allows photography/documentation. Lesions appear as irregular masses with abnormal vasculature; the examiner assesses for fixation, extension to adjacent structures,

Contraindicated/avoid: blind sedation of the stridulous patient, cricothyrotomy through tumor, open incisional biopsy of a neck node before workup (FNA instead), and re-irradiation without multidisciplinary review.