Nasopharyngeal Carcinoma – Comprehensive Study Notes

Introduction

• Nasopharyngeal carcinoma (NPC)

  • One of the commonest epithelial malignancies of adulthood, arising from mucosal epithelium of the nasopharynx.

  • Historically difficult to diagnose early because the nasopharynx is hidden from routine clinical inspection.

  • Quote from lecture: “…diagnosis of many conditions, frequently serious, has often been missed and delayed…”.

• Learning objectives (as per slide)

  • Understand nasopharyngeal anatomy.

  • Recognise risk factors & epidemiology.

  • Master clinical presentation & diagnostic work-up.

  • Become familiar with treatment modalities & follow-up.

Anatomy of the Nasopharynx

• Definition: Hollow, mucosa-lined conduit connecting nasal cavity → oropharynx.

• Boundaries

  • Anterior: Posterior choanae & nasal cavities

  • Roof/Superior: Sphenoid bone + clivus

  • Posterior: Clivus + $C_1$ vertebra

  • Inferior: Soft palate & oropharynx

  • Lateral: Eustachian tube orifices, torus tubarius, Rosenmüller’s fossa

  • Rosenmüller’s fossa = MOST common origin of NPC.

• Histology of lining

  • Stratified squamous OR pseudostratified columnar epithelium.

  • Contains minor salivary glands & lymphoid (adenoidal) tissue.

Functions of the Nasopharynx

• Air conduit: receives warmed/humidified air → larynx & trachea.

• Ventilation of middle ear via Eustachian tube → pressure equalisation across tympanic membrane.

• Contributes to resonance in speech (hyper-/hyponasality when affected).

Epidemiology

• General

  • Uncommon worldwide but shows strong geographic clustering.

• High-incidence / endemic regions

  • Southern China, South-East Asia, Alaska.

  • In endemic zones NPC constitutes $18–25\%$ of all cancers (Breda et al., 2010).

• Incidence rates

  • $10–53$ / $100{,}000$ person-years in endemic zones.

  • Africa: $5–7$ / $100{,}000$ (Hila et al., 2009).

  • Ghana data: $1.2\%$ of all cancers & $29\%$ of head–neck cancers (Kitcher 2004; Larsen-Reindorf 2014).

• Age & sex

  • Bimodal age: peak in 4th–5th decades; smaller peak in late teens/children.

  • Male : female ≈ $2–3:1$.

Aetiology (Multifactorial)

• Genetic predisposition

• Viral oncogenesis (EBV)

• Dietary & environmental carcinogens

• Additional exposures: tobacco, alcohol, wood dust, incense, opium.

Genetic Factors

• Southern Chinese (Fujian & Cantonese) have $\approx 100\times$ higher risk than Caucasians.

  • Persistence of risk in 2nd-generation migrants ⇒ heritable component dominates environment.

• Chromosomal & molecular changes

  • Losses on $3p$ & $9p$ ⟹ inactivation of tumour-suppressors $p14, p15, p16$.

  • Oncogenes / regulators: $AKT1, p53, MDM2, LMP1, PTEN$ frequently mutated or dysregulated.

Viral Factors – Epstein–Barr Virus (EBV)

• Strongest infectious association.

• Serology

  • Elevated IgA & IgG against viral capsid antigen (VCA) & early antigen.

  • $80–85\%$ of NPC patients have positive IgA titres; titres fall post-therapy ⇒ monitoring tool.

• Ghanaian series: EBV (type 2) isolated in $52\%$ of NPC patients (Ayee 2020).

• EBV latent membrane proteins (LMP1/LMP2) promote pathogenesis (Dawson 2012).

Dietary / Environmental Factors

• Childhood & lifelong consumption of preserved fish (salted, dry, ungutted) → high nitrosamine load.

• Other salted foods (shrimp paste, pickled veg, soybeans) implicated.

• Protective: high fruit/veg intake (Vit C inhibits amine nitrosation).

Other Carcinogens

• Cigarette smoking; Alcohol

• Occupational wood dust

• Burning incense exposure

• Opium use

Histopathology

• WHO Classification (Light microscopy)

  • Type I Keratinising squamous cell carcinoma

  • Type II Differentiated non-keratinising carcinoma

  • Type III Undifferentiated carcinoma (lymphoepithelioma)

  • Types II & III = endemic forms; classically EBV-associated; radio-chemo-sensitive.

Clinical Presentation

• Early detection hindered by deep location; majority present with advanced disease.

• Four broad symptom clusters:

  1. Nasal (≈$80\%$ of patients)

  • Discharge, epistaxis, obstruction, hyponasal speech, altered smell.

  1. Otologic (Eustachian tube dysfunction)

  • Conductive hearing loss, aural fullness, tinnitus, unilateral serous otitis media (middle-ear effusion in adult ⇒ red-flag for NPC).

  1. Ophthalmo-neurologic (skull-base/cranial nerve involvement)

  • Headache, facial/retro-orbital pain

  • Cranial nerve III, IV, V, VI → diplopia, ophthalmoplegia, reduced corneal reflex, proptosis, blindness.

  • Lower cranial nerves IX-XII involvement → dysphagia, hoarseness, shoulder weakness, Horner’s syndrome.

  1. Cervical nodal metastasis

  • High-jugular & posterior-triangle nodes; often bilateral, firm, painless; may be first/only sign.

• Patterns of spread (illustrated in lecture)

  • Tumour extends via foramen lacerum/ovale to cavernous sinus → CN palsies.

  • Parapharyngeal & retropharyngeal spaces → neck stiffness, pain, trismus (pterygoid invasion).

  • Hematogenous metastasis: lung, liver, bone.

Diagnostic Work-up

• Comprehensive history + ENT examination with rigid/flexible nasoendoscopy.

• ALWAYS biopsy suspicious nasopharyngeal lesion OR node with unknown primary.

Laboratory

• Routine FBC, serum chemistries.

• EBV serology: IgA/IgG VCA, early antigen titres (diagnosis + surveillance).

Imaging

• Contrast CT head & neck ⇒ tumour extent, skull-base erosion, nodal map.

• MRI superior for intracranial extension.

• Bone scan for osseous metastases.

• Chest X-ray or CT thorax for pulmonary mets.

Procedures (Gold standard)

• Endoscopic transnasal biopsy under local anaesthesia (LA) or general anaesthesia (GA).

• Fine-needle aspiration / excision biopsy of cervical node if primary inaccessible.

Staging Systems (mention only)

• American Joint Committee on Cancer (AJCC / TNM).

• International Union Against Cancer (UICC).

• Ho system (historical).

Treatment Principles

• Aims

  • Curative intent for loco-regional disease.

  • Palliation for metastatic/unresectable cases.

• Multidisciplinary team: ENT surgeon, oncologist, radiologist, pathologist, specialised nurses, dietician, speech therapist.

Radiotherapy (RT)

• Primary modality for stages $I \rightarrow IVB$ (all but distant mets).

• External beam RT total dose $65–70\,\text{Gy}$ over $6–7$ weeks.

• Intensity-modulated RT (IMRT) now standard: spares salivary glands & critical neural structures.

Chemotherapy

• Added for advanced loco-regional disease to improve control & survival (Al-Sarraf 1998 landmark).

• Timing

  1. Neoadjuvant (induction) → shrink tumour prior to RT.

  2. Concurrent (chemo-RT) → radiosensitisation.

  3. Adjuvant → eradicate micro-mets post-RT.

• Active agents

  • Cisplatin (corner-stone)

  • $5$-Fluorouracil (5-FU)

  • Doxorubicin, epirubicin

  • Bleomycin

  • Mitoxantrone

  • Methotrexate

Surgery – Limited Role

• Indications

  • Diagnostic biopsy of primary / nodes

  • Neck dissection for residual or recurrent nodal disease after RT/chemo.

  • Tracheostomy for airway compromise.

  • Surgical exposure for brachytherapy or local excision (rare).

  • Emerging: Endoscopic skull-base resections for selected persistent disease (still investigational).

Follow-up Strategy

• Essential for early detection of recurrence, second primary tumours, & management of RT sequelae.

• Schedule

  • Every $2–3$ months during first $3$ years post-therapy.

  • Every $6$ months during years $4$–$5$.

  • Annually up to year $7$ (many centres lifelong due to late effects).

• Team members: Oncologist, Head-&-Neck surgeon, Speech therapist, Dentist (manage xerostomia, trismus, osteoradionecrosis).

Prognosis & Key Takeaways

• NPC, though rare globally, has high cure rates when detected early and treated with modern chemo-RT protocols.

• EBV serology useful for screening in endemic areas and monitoring post-treatment response.

• Importance of considering NPC in adults with unilateral serous otitis media or unexplained cervical nodes.

Ethical / Practical Considerations

• Endemic regions should implement community education about early symptoms (epistaxis, hearing loss) to reduce diagnostic delay.

• Genetic & viral screening raises issues of privacy and access; counselling essential.

• Long-term survivors face RT-related morbidity (xerostomia, dysphagia, hearing loss) ≠ mere survival; holistic care & rehabilitation mandatory.

Connections to Broader Principles

• Illustrates classic model of virus–host–environment interaction in carcinogenesis.

• Serves as paradigm for combined-modality oncology (chemo-RT synergy).

• EBV-targeted vaccines and immunotherapies are being explored, linking virology with precision oncology.

High-Yield Numbers & Facts (Quick Reference)

• Incidence endemic $10–53/100{,}000$; Africa $5–7/100{,}000$.

• Male : Female $2–3:1$; peaks 40–50 yrs & teens.

• EBV IgA positive in $\approx 80–85\%$ cases.

• RT dose $65–70$ Gy; follow-up q$2–3$ months (yrs 1–3).

Select References for Further Reading

• Breda E et al., Braz J Otorhinolaryngol 2010 – EBV detection in low-risk area.

• Hila L et al., Pathol Biol 2009 – Tunisian epidemiology.

• Larsen-Reindorf R et al., IJ Oto HNS 2014 – Ghanaian series.

• Dawson CW et al., Semin Cancer Biol 2012 – Role of LMP1/2.

• Al-Sarraf M et al., JCO 1998 – Concomitant chemo-RT landmark trial.

End of study notes.