Overview
NPC is the second most common head and neck cancer in Kenya. It has a high incidence in Southern China and a moderate incidence in Kenya and Northern Africa. Areas with high incidence have a single peak incidence at age 35-50 years while low incidence areas have a double peak at 9-15 years and 35-50 years. It affects males more than females with a M:F ratio is 3:1. Site of origin is the Fossa of Rosenmuller.
WHO classification of NPC
| WHO Type | Histology | Subtypes |
|---|---|---|
| WHO Type I | Keratinizing SCC | Squamous differentiation, not associated with EBV, sporadic, worse prognosis, less sensitive to radiation |
| WHO Type II | Non-Keratinizing SCC | No definite squamous differentiation, associated with EBV, endemic, better prognosis and sensitive to radiation |
| WHO Type III | Undifferentiated SCC | Lymphoepithelioma, anaplastic and clear cell variants. Indistinct cell margins, may have lymphocytic stroma. EBV, endemic (Souther China), bette rprognosis, sensitive to radiation |
Other types of NPC: Lymphoma, adenocarcinoma, plasma cell myeloma, cylindroma, adenoid cystic carcinoma, melanoma, carcinosarcoma, unclassified spingling malignant neoplasm
- Forms of NPC
- Proliferative: extends locally causing obstructive nasal symptoms
- Ulcerative: a lot of bleeding (epistaxis)
- Infiltrative: bony involvement, may spread to the brain
Anatomy of the Nasopharynx
The post-nasal space measures 4cm high, 4cm wide, and 2 cm deep. It is lined by stratified squamous columnar epithelium and pseudostratified columnar epithelium. It also contains lymphoid tissue.
Fossa of Rosenmuller: a slit-like region medial to the medial crura of the eustachian tube orifices. It is the most common site of nasopharyngeal tumors.
Passavant’s Ridge: Interdigitating superior constrictor muscles that form a band at the posterior pharyngeal wall during swallowing. It abuts the soft palate.
Boundaries of the post-nasal space
| Boundary | Structure |
|---|---|
| Anterior boundary | Choana and nasal septum |
| Posterior boundary | Superior pharyngeal constrictor muscles, Bodies of C1-C2 in continuity with the roof |
| Roof | Base of skull (body of sphenoid) |
| Floor | Soft palate and opening of oropharynx |
| Lateral boundary | Eustachian tube orifices and fossae of Rosenmuller |
Clinical Features and Treatment
- Risk factors
- Demographics
- Male
- Regional distribution: More common in Chinese or Mongolians. Southern China, Northern Africa, Southeast Asia, Alaska and Greenland)
- Infections
- Epstein-Barr Virus (EBV) – Viral Capsule Antigen (VCA) and Early Intracellular Antigen (EA)
- Elevated IgA VCA and EA can be used to screen for NPC in high-risk regions
- Low titers of IgA VCA and EA predicts poor prognosis, Higher titres predict good prognosis
- Genetic predisposition:
- Inheritance of certain HLA genes- HLA A2, HLA B17, HLA B46
- Family history
- Environmental factors: as evidenced by the regional distribution
- Polycyclic hydrocarbons
- Chronic nasal infection
- Poor hygiene
- Poor ventilation
- Smoke
- Demographics
- Signs and symptoms
- Neck mass (70%)
- Painless
- Otitis media with effusion (secondary to eustachian tube obstruction, 50%)
- Nasal obstruction
- Cranial nerve palsies (abducens nerve palsy is the most common)
- Recurrent epistaxis
- Trismus
- Headache
- Neck mass (70%)
- Diagnosis
- Routine labs: CBC, LFT (r/o metastasis)
- Rigid nasal endoscopy with biopsy
- To rule out metastasis:
- Fine needle aspiration of enlarged lymph nodes
- CECT base of skull to thoracic inlet: metastasis
- CECT Abdomen
- CXR
- Treatment
- Stage I-II (non-surgical)
- Radiotherapy to the primary site and bilateral necks (regardless of nodal status)
- Stage II-IV
- Concurrent Chemoradiation w/Cisplatin/5-FU
- Followed by adjuvant chemotherapy
- Neck dissection for post-radiation salvage surgery
- Tracheotomy if there are airway issues
- Supportive treatment: analgesia
- Stage I-II (non-surgical)
- Differentials
- Other nasopharyngeal tumors Benign Malignant Angiofibroma Lymphoma Choanal polyp Rhabdomyosarcoma Squamous papilloma Chordoma Craniopharyngioma Plasmacytoma Hamartoma Malignant salivary tumor
Signs and symptoms according to region
| Nose | Nasal obstruction, Epistaxis, Rhinorrhoea, Nasal mass |
|---|---|
| Neck | Painless Neck mass |
| Ear | Ear blockage, Fullness, CHL, OME, Otalgia |
| Throat | Oropharyngeal mass, Displaced palate, Post-nasal drip, Hyponasal speech, Dysphagia, Odynophagia, Airway obstruction |
| Eye | Proptosis, Visual disturbance, Impaired eye movement |
| Central Nervous System | Xerophthalmia (greater superior petrosal nerve), Facial pain (trigeminal nerve), Diplopia (CN VI), Ophthalmoplegia (CN II, IV, VI), Horner syndrome (sympathetic trunk), Headache, Convulsions |
Staging of NPV (AJCC, 2017)
Tumor
| Stage | Definition |
|---|---|
| Tx | Primary tumor not assessed |
| T0 | No primary tumor |
| Tis | Carcinoma in situ |
| T1 | Tumor confined to the nasopharynx, or extension to the oropharynx/nasal cavity w/o parapharyngeal involvement |
| T2 | Tumor extends to the parapharyngeal space and/or adjacent soft tissue (pterygoid mm, prevertebral muscles) |
| T3 | Tumor involves bony structures of skull base/cervical vertebrae/pterygoid and/or paranasal sinus |
| T4 | Tumor invades intracranially/cranial nerves/hypopharynx/orbit/parotid gland and/or extensive soft tissue infiltration beyond the lateral surface of the lateral pterygoid |
Node
| Stage | Definition |
|---|---|
| Nx | Nodes cannot be assessed |
| N0 | No regional LN metastasis |
| N1 | Unilateral metastasis in cervical LN and/or unilateral or bilateral metastasis in retropharyngeal LNs, ≤ 6 cm above the caudal border of cricoid cartilage |
| N2 | Bilateral metastasis in Cervical LNs, ≤ 6 cm above the caudal border of the cricoid cartilage |
| N3 | Unilateral or bilateral metastasis in cervical LNs >6cm and/or extension below the caudal border of the cricoid cartilage |
Metastasis
| Stage | Definition |
|---|---|
| M0 | No distant metastasis |
| M1 | Distant metastasis |