Chapter 41 Nasopharyngeal Carcinoma Flashcards
Describe boundaries of Nasopharynx
Anterior Nasal cavity via posterior choanae
Inferior Oropharynx
Roof Basilar portion of sphenoid and occipital bones
Floor superior surface of soft palate and nasopharyngeal isthmus
Lateral Pharyngotympanic tube(Eustachian tube) opening
Posterior superior pharyngeal constrictor muscle, pharyngobasilar fascia, buccopharyngeal fascia
Describe torus tubarius
Formed by cartilage of pharyngotympanic tube elevating mucous membrane of lateral nasopharynx
Most common site of origin of nasopharyngeal malignancies
Fossa of Rosenmullar
Define sinus of Morgagni and structures that pass through it
Lateral area of muscular deficiency in superior pharyngeal constrictor muscle
Pharyngotympanic tube and levator veli palatini
What does proximity of foramen lacerum, foramen ovale, foramen spinosum, jugular foramen, hypoglosal canal, carotid space with sinus of morgagni signify?
Intracranial extension
Nerve supply of Nasopharynx
Afferent innervation
-anterior to pharyngotympanic tube orifice V2(Trigeminal nerve)
-posterior to tubal orifice Glossopharyngeal nerve
Motor innervation
-Pharyngeal branch of IX, X and sympathetic fibers from superior cervical ganglion
Blood supply of Nasopharynx
Arterial supply
Ascending Pharyngeal artery
Sphenopalatine artery
Artery of pterygoid canal
Venous drainage
Pharyngeal plexus drains into internal jugular vein, directly or via communication with pterygoid plexus
Bimodel distribution of Nasopharynx in low risk and high risk
Low risk
1st peak 15-25 years
2nd peak 50-59 years
High risk
4th and 5th decade of life
Most prevalent cases of Nasopharynx in the world
Hong Kong and Guangdong Province in southern China
26.9 per 100,000 people per year
3 major cause of Nasopharyngeal Carcinoma
- Genetic - Gene closely linked to HLA locus
- Environmental - high salt, alcohol, smoking, exposure to dust,fumes,formaldehyde
- Viral - EBV
Proteins predominantly expressed in NPCA induced by EBV infection
Latent Membrane Protein (LMP1, LMP2A, LMP2B)
EBV determined nuclear antigens(EBVA1, EBVA2)
Name principle oncogene which play likely etiologic role for EBV in NPC
LMP1 Latent Membrane Protein 1
Foramina of base of skull and associated anatomic structure
Cribiform plate
olfactory nerve
ant ethmoidal artery
Optic foramina
Optic nerve
Opthalmic artery
Superior orbital fissure
III,IV,V1,VI Ophthalmic vein orbital branch of middle meningeal and recurrent branch of lacrimal arteries sympathetic plexus filaments from carotid plexus
Foramen rotundum
V2
Foramen ovale
V3
accessory meningeal artery
lesser superficial petrosal nerve
Foramen lacerum
internal carotid sympathetic carotid plexus Vidian nerve meningeal branch of ascending pharyngeal artery Emissary vein
Foramen spinosum
Recurrent branch of V3 nerve
Middle meningeal artery and vein
Stylomastoid foramen
Facial nerve
Internal acoustic meatus
Auditory nerve VIII
Internal auditory artery
Jugular foramen
IX,X,XI
Inferior petrosal sinus
Transverse sinus
Meningeal branches from occipital and ascending pharyngeal arteries
Hypoglosal canal
XII
Meningeal branch of ascending pharyngeal artery
Foramen magnum
Spinal canal
Spinal accessory nerve
Vertebral vessels
Anterior and posterior spinal vessels
Structures locally infiltrated by NPC anteriorly.
Nasal fossa - lateral wall invasion can lead to involvement and destruction of pterygoid plates
Less common - posterior ethmoid and maxillary sinus
Advanced stage - orbital apex, inferior orbital fissure
Structures locally infiltrated by NPC superiorly and posteriorly
Superior
base of skull, sphenoid sinus, Clivus
foramen lacerum positioned directly above pharyngeal recess(fossa of Rosenmullar), merkel’s cave,foramen ovale, petrous part of temporal bone
Posterior
Prevertebral muscle longus capitus
Structures locally infiltrated by NPC inferiorly
Oropharynx
Advanced disease - C1 vertebra
Structures locally infiltrated by NPC laterally
Parapharyngeal space along with invasion of levator and tensor veli palatini muscles
Advanced disease - invasion of pterygoid muscles, direct invasion or compression of internal carotid artery
Invade middle ear through pharyngotympanic tube
Lymphatic drainage of Nasopharynx
2 major lymph collectors that runs along lateral and posterior side of pharyngeal wall.
1.Lateral lymph collector drainage sites
Lateral pharyngeal node
Jugulodigastric/Subgastric node
3rd/4th/5th node of retropharyngeal group
2.Posterior lymph collector drainage sites
1st node of Retropharyngeal group(node of Rouviere)
Most common level of lymph node involved in NPC
Level IIb
Percentage of distant metastasis in NPC at presentation and during disease process.
At presentation : 3-6%
During disease process : 18-50%
Risk factor of distant metastasis in NPC
Advanced neck node metastasis esp low neck involvement
Most common site of distant metastasis in NPC
Most common : Bone
- Lung
- Liver
Brain and Skin : Rare
Clinical presentation of NPC
Upper neck mass
Mass in Nosopharynx : Epistaxis, Nasal obstruction
Skull base erosion : headache,cranial nerve palsy
Most common presenting symptom in NPC
Neck mass followed by nasal and aural symptoms
Cranial nerve frequently involved in NPC
VI 13.3%
V 7.8%
(Chai and Perez et al)
Ng et al How is MRI superior to CT in assessing tumor extent in NPC
Higher sensitivity for skull base involvement(60% vs 40%) Intracranial involvement(57% vs 36%) RP node(58% vs 21%) Tumor infiltration prevertebral muscles(51% vs 22%)
Van den Brekel et al LN mets radiologically defined in H&N as
Presence of central necrosis ECS Shortest axial diameter >=10mm (11mm jugulodigastric node, 5mm RP node) Cluster of 3 or more node that are borderline in size
Name 2 tumor markers for NPC
IgA anti VCA(Viral Capsid Antigen)
IgG anti-EA(Early Antigen)
Oropharyngeal extension T stage?
T1
Paranasal extension T Stage?
T3
Hypopharyngeal extension T stage?
T4
T4 stage extension in NPC
Intracranial extension Cranial nerve involvement Hypopharynx Orbit Infratemporal fossa/masticator space
T1N0 NPC stage?
Stage I
T2N1 NPC what stage?
Stage II
T3N2 NPC stage?
Stage III
T4N2 NPC stage?
Stage IVA
Any T N3 NPC stage?
IVB
Define boundaries of supraclavicular fossa?
Triangular region defined by
Superior margin of sternal end of clavicle
Superior margin of lateral end of clavicle
Point where neck meets the shoulder
Pathologic classification WHO 2005 NPC
Keratinizing SCC
Non Keratinizing SCC
Differentiated
Undifferentiated
Basaloid SCCWhich pathologic subtype of NPC strongly associated with EBV?
Non Keratinizing SCC
Most important prognostic factor in NPC
TNM staging
Poor prognostic factors in NPC
Bone erosion
Cranial nerve palsy
Lower nodal involvement
Extension to prestyloid space or anterior part of masticator space
Parapharyngeal space extension(controversial)
Prevertebral Space Involvement(PSI)
Gross volume of primary tumor(GTV-P)
Better prognosis for female and younger patients
Sensitivity and specificity of plasma EBV DNA for detecting NPC(Lo et al)
Sensitivity 96%
Specificity 93%
Clinical trials that found high pretreatment plasma EBV DNA level associated with advanced stage and poorer prognosis in NPC
Lo et al
Lin et al
Leung et al
Clinical trials that found posttreatment plasma EBV DNA level strong predictor of outcome in NPC
Le et al
Wang et al
An et al
Biologic markers expressed in NPC associated with prognosis
EGFR
HIF 1alpha
CA IX
VEGF
E-catherin and beta-catenin c-erbB2 p53 NM23-HI Interleukin-10
Local Control Rate NPC
T1-2 >70Gy vs 66-70Gy
T3-4 >70Gy
Perez et al
100% vs 80%
<55%
What is the most important radiation factor in NPC
Total dose or Dose fraction?
Total dose
Lee et al prophylactic neck irradiation in clinically negative neck vs untreated, what was the nodal recurrence rate in NPC?
11% vs 40%
Describe high risk subclinical CTV
(CTV59.4Gy) in NPC
GTV + Entire Nasopharynx Retropharyngeal node Clivus Skull base Pterygoid fossa Parapharyngeal space Sphenoid sinus Posterior 1/4th to 1/3rd of nasal cavity and maxillary sinus Nodal regions: bilateral upper jugular,submandibular,subdigastric,midjugular, posterior cervical,retropharyngeal.
