Head and Neck Cancer¶
Chapter 82 | Part 4: Oncology and Hematology
KEY CLINICAL POINTS¶
- Head and neck cancers account for ~6% of adult malignancies in the US (66,920 new cases in 2023), with 15,400 deaths annually.
- HPV (especially HPV-16) is a major driver of oropharyngeal cancers, particularly in younger patients, with ~50% of US cases being HPV-related.
- Alcohol and tobacco synergistically increase risk, while EBV is strongly associated with nasopharyngeal cancer in endemic regions.
- TNM staging is critical for prognosis and treatment planning, with HPV-positive tumors showing better outcomes despite advanced stages.
- De-escalation strategies (lower radiation doses, omitting chemotherapy) are being explored for HPV-related cancers to reduce long-term toxicity.
1. DEFINITION & OVERVIEW¶
Head and neck cancers encompass malignancies of the oral cavity, pharynx, larynx, salivary glands, and thyroid. They are classified by histology (e.g., squamous cell carcinoma, salivary gland tumors) and anatomical location. HPV-related oropharyngeal cancers have distinct epidemiology and better prognosis compared to traditional tobacco/alcohol-associated cancers.
TNM Staging System (AJCC 8th Edition)¶
| Stage | Tumor (T) | Nodes (N) | Metastasis (M) |
|---|---|---|---|
| Stage I | T1 N0 M0 | T1 N0 M0 | T1 N0 M0 |
| Stage II | T2 N0 M0 | T2 N0 M0 | T2 N0 M0 |
| Stage III | T3 N1 M0 | T3 N1 M0 | T3 N1 M0 |
| Stage IVA | T4a N2 M0 | T4a N2 M0 | T4a N2 M0 |
| Stage IVB | T4b N3 M0 | T4b N3 M0 | T4b N3 M0 |
| Stage IVC | Any T Any N M1 | Any T Any N M1 | Any T Any N M1 |
1.1 Subtopic¶
Head and neck cancers are broadly categorized into squamous cell carcinomas (SCCs) and non-SCCs (e.g., salivary gland, thyroid). SCCs account for ~90% of cases and are further classified by differentiation (well, moderately, poorly).
2. EPIDEMIOLOGY¶
Global incidence exceeds 500,000 annually. In the US, 66,920 new cases in 2023 (6% of adult malignancies), with 15,400 deaths. Risk factors include age (>60 for tobacco-related cancers), male sex (2:1 ratio), and geographic variation (e.g., nasopharyngeal cancer endemic in East Asia).
2.1 Demographics¶
Males > females (2:1 ratio). HPV-related oropharyngeal cancers peak in 40s-50s, while nasopharyngeal cancer occurs across all ages, including adolescents.
2.2 Risk Factors¶
Alcohol/tobacco synergism, HPV (especially HPV-16), EBV, occupational exposures (nickel, woodworking), and dietary factors (low fruit/vegetable intake).
3. ETIOLOGY & PATHOPHYSIOLOGY¶
Multifactorial etiology including environmental carcinogens (alcohol, tobacco), viral agents (HPV, EBV), and genetic factors. HPV oncogenes inhibit p53/RB pathways, while EBV is linked to nasopharyngeal lymphoepithelioma. Genetic alterations include p53 mutations, PI3K pathway activation, and HRAS mutations in recurrent disease.
3.1 Viral Etiology¶
HPV (especially HPV-16) drives oropharyngeal SCC; EBV causes nasopharyngeal carcinoma. Kaposi’s sarcoma is linked to HHV-8.
3.2 Molecular Mechanisms¶
HPV oncogenes inhibit p53/RB pathways; EBV latent membrane protein-1 (LMP-1) mimics CD40 signaling. Genetic instability and EGFR overexpression are common in SCCs.
4. CLINICAL FEATURES¶
Symptoms vary by site: oral cavity (nonhealing ulcers, denture changes), larynx (hoarseness), nasopharynx (unilateral otitis media, epistaxis). HPV-related tumors often present with cervical lymphadenopathy as the first sign. Advanced disease causes pain, airway obstruction, and cranial neuropathies.
4.1 Common Presentations¶
Oral cavity: nonhealing ulcers, denture discomfort. Oropharynx: dysphagia, otalgia. Larynx: persistent hoarseness. Nasopharynx: unilateral nasal obstruction, hearing loss.
4.2 Premalignant Lesions¶
Leukoplakia (white patches), erythroplakia (red patches), and oral submucous fibrosis may precede malignancy and require biopsy.
5. DIFFERENTIAL DIAGNOSIS¶
Includes Kaposi’s sarcoma, EBV-related nasopharyngeal lymphoepithelioma, and other malignancies (e.g., thyroid cancer). Differentiate from benign conditions like mucocele or ranula.
5.1 Key Differentiators¶
HPV-related oropharyngeal cancer: young age, cervical lymphadenopathy, better prognosis. EBV-related nasopharyngeal cancer: endemic regions, lymphoepithelioma histology.
6. INVESTIGATIONS & DIAGNOSIS¶
Physical exam (panendoscopy, palpation), imaging (CT/MRI), and biopsy. HPV testing is critical for oropharyngeal tumors. PET-CT aids in staging distant metastases.
6.1 Diagnostic Workup¶
Fine-needle aspiration (FNA) for occult primaries. Endoscopic biopsy for mucosal lesions. CT/MRI for staging. PET-CT for detecting distant metastases.
6.2 Biomarkers¶
HPV testing (E6/E7 oncogenes) for oropharyngeal SCC. EBV serology (VCA-IgA, EA-D) for nasopharyngeal cancer screening.
7. MANAGEMENT & TREATMENT¶
Curative intent for localized disease (surgery/radiation), multimodal therapy for advanced stages (chemoradiotherapy), and systemic therapy for metastatic disease. De-escalation strategies reduce toxicity in HPV-related cancers.
Chemoradiotherapy Regimens¶
| Drug | Dose | Schedule |
|---|---|---|
| Cisplatin | 40-60 mg/m² | Weekly during radiation (6-7 weeks) |
| Docetaxel | 60-80 mg/m² | Every 3 weeks |
| 5-FU | 1000-1500 mg/m² | Continuous infusion over 24 hours |
7.1 Localized Disease¶
Surgery for small oral cavity tumors; radiation for laryngeal preservation. Prophylactic neck dissection reduces recurrence.
7.2 Locally Advanced Disease¶
Concomitant chemoradiotherapy (cisplatin + radiation) is standard. Induction chemotherapy (docetaxel/cisplatin/5-FU) may precede surgery.
7.3 Recurrent/Metastatic Disease¶
Systemic chemotherapy (cisplatin + 5-FU + cetuximab). Palliative radiation for symptom control. Targeted therapies (e.g., pembrolizumab) for HPV-positive tumors.
8. PROGNOSIS & COMPLICATIONS¶
5-year survival: 60-90% for localized disease, 50-60% for advanced stages. HPV-positive tumors have better outcomes. Complications include xerostomia, osteoradionecrosis, and secondary malignancies.
8.1 Prognostic Factors¶
HPV status, nodal involvement, differentiation grade, and response to chemoradiotherapy. HPV-positive tumors show improved survival despite advanced stages.
8.2 Long-term Toxicity¶
Radiation-induced fibrosis, swallowing dysfunction, and osteoradionecrosis. De-escalation strategies aim to mitigate these effects.
9. SPECIAL CONSIDERATIONS¶
Pregnancy: avoid radiation/chemotherapy. Pediatrics: rare but possible (e.g., nasopharyngeal cancer). Elderly: higher comorbidity but may tolerate aggressive therapy. HPV-related cancers benefit from de-escalation.
9.1 HPV-Related Cancers¶
De-escalation protocols (lower radiation doses, omitting chemotherapy) are being tested to reduce toxicity while maintaining efficacy.
10. KEY POINTS & CLINICAL PEARLS¶
- HPV-related oropharyngeal cancers are increasing in incidence and have better prognosis than traditional SCCs.
- Early detection via HPV testing and panendoscopy is critical for improved outcomes.
- Concomitant chemoradiotherapy (cisplatin + radiation) is the standard for locally advanced disease.
- De-escalation strategies are being explored to reduce long-term toxicity in HPV-positive patients.
- Second malignancies are common in survivors, necessitating regular follow-up.