Salivary Gland Tumors
Marka Crittenden M.D. Ph.D.
Anatomy
• Major Glands
– Parotid, submandibular and sublingual glands
• Minor Glands
– Hundreds residing in the oral cavity, pharynx and
paranasal sinuses.
Major Salivary Glands
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Parotid Gland
• Borders
– Superior – zygomatic arch.
– Posterior – angle of mandible under earlobe toward the mastoid tip.
– Inferior – extends to the inferior aspect of the angle of mandible
toward hyoid bone.
– Medial – borders of the parapharyngeal-base of skull.
– Lateral – below the skin of the preauricular cheek-upper neck.
– Anterior – wraps around ascending ramus of mandible
• Facial nerve divides the gland into the superficial (80 %) and deep
lobe (20%)
• Parotid duct (Stensons) is 5 cm long and opens opposite the second
molar.
• Lymphatic drainage – periparotid/intraparotid – lvl I – lvl II- lvl III.
• Accessory parotid lobe – Present in 20% of patients.
Submandibular Gland
• Borders
– Lateral – proximal half of the mandible.
– Posterior – anterior to but near the low anterior margin of the
parotid gland.
– Inferior – approaches the level of the hyoid bone.
– Majority of gland lies over the external surface of the mylohyoid
muscle.
– Lateral to and abuts the lingual and hypoglossal nerve and is
medial to the marginal mandibular and cervical branch of the
facial nerve.
• Drains through Wharton’s duct in anterior floor of the
mouth
• Lymphatic Drainage Lvl I – Lvl II- Lvl III
Sublingual Gland
• 10% size of parotid gland
• Located anterior floor of the mouth
• Borders
– Lateral –medial aspect of mandible
– Inferior –mylohyoid muscle
• Lingual nerve courses adjacent to sublingual
gland
• Drain into the floor of the mouth through Rivinus
ducts
• Lymphatic drainage – Lvl I- Lvl II- Lvl III
Epidemiology
• Salivary tumors 7% of head and neck tumors
• Parotid tumors 10x more common then submandibular
and 100x more common then lingual
• Parotid 80% benign (pleomorphic adenoma)
• Submandibular 50% malignant
• Sublingual majority (65-88%) are malignant
• Equal incidence between sexes
• Risk Factors: nutritional deficiency, exposure to ionizing
radiation, UV exposure, genetic predisposition, EBV
Pathology
• Benign Tumors
– Pleomorphic Adenomas
• Malignant tumors
– Parotid – mucopidermoid most common – low
grade, slow growing cured by surgery alone
– Submandibular and minor salivary – adenoid
cystic most common.
Adenoid Cystic
• Cribiform pattern – differentiated
• Cribiform/solid pattern – moderately
differentiated
• Solid Features – undifferentiated
• Natural history ranges from months to greater
then 20 years.
• Lymph Node spread <5%
Adenoid Cystic
• Perineural spread common and can track
along the cranial nerves back to the base of
skull
• 40% develop pulmonary mets but survival of
10-20 years can occur with pulmonary mets so
primary must be managed
Metastatic Disease involving Parotid
• Mechanism
– Lymphatic spread – most common from skin
– Hematogenous spread - lung
– Direct extension – skin or osseous sarcomas
Staging
• T1 ≤ 2cm and no extraparenchymal extension
• T2 > 2cm but not >4cm without
extraparenchymal extension
• T3 >4cm and or extraparenchymal extension
• T4a invades skin, mandible, ear canal and/or
facial nerve
• T4b invades skull base and or pterygoid plates
and or encases carotid artery
Parotid Tumors
• Clinical presentation
– Asymptomatic mass
– Cranial nerve palsey – inability to move one side of
face, one shoulder, one side of tongue.
• Evaluation
– Trismus – to evaluate pterygoid involvement
– CT/MRI
– FNA in parotid tumors 90% sensitive and >95%
specific
– Never perform incisional or excisional biopsy
Parotid Tumors
• Lymph Nodes
– Rare in adenoid cystic
– 12% positive in clinically negative tumors.
• Size and grade are risk factors
– >4 cm 20% occult mets vs 4% in smaller tumor
– High grade 49% risk regardless of histologic type vs 7% for low or
intermediate
• Distant Spread
– Lung
• 25-35% risk for mucoepidermoid, adenoid cystic and
malignant mixed tumors.
• Routine CXR
Postoperative Radiation versus Surgery for Salivary
Gland Tumors: Results from the literature
Series
#
PTs
FUP
Prognastic
length factors
(y)
LC 5y
Surv 5y
S S/R S S/R
MSKCC
92
S 10.5 Stage I/II
S/R 5.8 Stage III/IV
Positive nodes
High-Grade
79
17
40
44
JH
87
MDACC
155
PMH
271
91
51
69
63
96
9.5
19
28
82
51
49
57
75
All patients
58
92
59
7.5
All patients
58
86
50-56 66-72
10
All patients
-
29
68
(RFS)
Submandibular tumor
• Clinical presentation
– Asymptomatic mass
– Painful mass as enlarges
– Cranial nerve palsey –decrease sensation in ipsilateral lower
teeth, lip and gums, inability to move ipsilateral oral tongue or
inbality to move part of face.
• Evaluation
– CT/MRI – help to distinguish a pseudomass
– FNA in submandibular tumors useful only if reveals a
malignancy.
– All lesions approached with a submandibular triangle dissection
– Almost never perform incisional or excisional biopsy.
Submandibular Tumors
• Lymph Nodes
– 28% risk in submandibular tumors
– Lvl I, II and III most common sites
• Distant Spread
– Lung >bone and liver
Sublingual Tumors
• Clinical presentation
– Asymptomatic swelling in floor of mouth
– Cranial nerve palsey – ipsilateral loss of sensation
of one side of tongue.
• Evaluation
– CT/MRI
– Most tumors are malignant so FNA only useful if
maligant
– Always resect with a formal cancer surgery
Sublingual Tumors
• Lymph Nodes
– Higher risk of LN spread then parotid tumors
– Lvl I is first site of drainage
• Distant Spread
– Lung > bones and liver
Treatment
• Surgery -Parotid
• 90% confined to superficial lobe – perform superficial
parotidectomy
• If adjacent to deep lobe - total parotidectomy
• If invades adjacent soft tissue – radical parotidectomy
• Never perform piecemeal excision in an attempt to preserve
facial nerve
• Nerve grafting can be performed and RT can start3-4 wk
post op without adverse affects
• Frey’s syndrome – (gustatory sweating) due to redirection of
parasympathetic and sympathetic nerve fibers to the dermal
sweat glands
Treatment
• Surgery - Submandibular
• Small tumor – gland excision
• ECE –En bloc resection with extended supraomohyoid
neck dissection
• Surgery – Sublingual
– Small and localized can resect without
submandibular gland
– Generally requires resection of submandibular
gland as well.
Treatment
• Radiation – Surgically unresectable tumors
– EBRT with photon and or electrons with
conventional or altered fractionation
– Brachytherapy ± EBRT
– Neutron therapy
Treatment
• Radiation – Surgically unresectable tumors
– EBRT
• Equivalent control rates as for equivalent head and
neck squamous cell cancers
– Early stage 71-100% control rates
– Late and Recurrent 50-70%
• Hyperfractionation
– Wang and Goodman reported on 14 patients using 1.6 Gy bid
to 65-70 Gy.
– 5 yr LCR 82%
Treatment
• Radiation – Surgically unresectable tumors
– Brachytherapy
• Used frequently with recurrent or advanced disease
• 5 yr LCR 60%
– Neutron therapy
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Biologic effect of neutrons less effected by hypoxia
Lethal effects less dependent on cell cycle
Repair of sublethal damage in malignant cells is less
RBE > 2.6
Severe late effect greater 17% versus 7%
Improved local control but no diff in overall survival
Treatment
• Postoperative Radiation
– Indications
• Close surgical margins (deep lobe parotid tumors, facial
nerve sparing)
• Microscopically positive margin
• High grade including adenoid cystic
• Involvement of skin, bone, nerve (gross or extensive
perineural invasion), tumor extension beyond capsule with
periglandular and soft tissue invasion
• LN spread
• Large tumors requiring radical resection
• Tumor spillage
• Recurrence
Treatment
• Postoperative Radiation
– LCR with surgery and post op RT
• T1 100% T2 83% T3 80% T4 43%
• Technique
– Parotid
• Electrons – lateral en face
• Mixed beam – 50-80% electron weighting lateral en
face or wedge pair.
• Photons - wedge pair or IMRT
Treatment
• Technique
– Portal margins – Parotid
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Superior – top of zygomatic bone
Inferior – hyoid bone – thyroid notch
Anterior - 2cm ant to upper second molar
Posterior – posterior to mastoid tip.
Lateral - 2 cm flash on cheek
Medial – 2 cm medial from ipsilateral oropharyngeal area.
Electron portal margins are 1 cm greater
Usually 12 MeV- 16 MeV energy used
Treatment
• Technique
– Portal margins – Submandibular
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•
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•
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Superior – 1cm above upper border of tongue
Inferior – Hyoid bone-thyroid notch interspace
Anterior – anterior aspect of mental symphysis
Posterior – BOT- jugulodigastric nodal area
Lateral – 2 cm flash of ipsilateral mandible
Medial – midline of tongue
Treatment
• Technique
– Portal margins – Sublingual
•
•
•
•
Superior – 1cm above upper border of tongue
Inferior – Hyoid bone-thyroid notch interspace
Anterior – anterior aspect of mental symphysis
Posterior – posterior aspect of the ascending
mandibular ramus
• Lateral – 2 cm flash of ipsilateral mandible
• Medial – 2cm past midline
Treatment
• Dosage – Primary treatment
– Accelerated fractionation with a delayed
concomitant boost
• Phase I 1.8Gy daily to 36 Gy
• Phase II 1.8 Gy as in phase I in AM x 10 fractions to
54Gy and > 6hrs 1.6 Gy to GTVx 10 fractions to 16 Gy
• Spinal cord dose < 45 Gy.
– IMRT to 70 Gy for GTV 63 Gy CTV 1 and 56 Gy
CTV2
Treatment
• Dosage – Post op treatment
– Administered within 6 weeks of surgery
– High Risk 2.0 Gy/fx to 60Gy and 1.8Gy/fx to 63Gy.
– Small volume known microscopic disease 66 Gy.
– Elective at risk 50 Gy (2.0Gy/fx) 54 Gy(1.8Gy/fx)
– Gross residual 70Gy.
Side effects
• Salivary fxn
– 80% of saliva produced by major salivary glands
– Loss of salivary fxn complete >35 Gy
– Dose limit to spare salivary function is 26 Gy.
• Trismus
– TMJ and masseter muscle < 50Gy. PT during and
after treatment
Adenoid Cystic Carcinoma
• Post op RT always recommended
• Post op RT of entire pathway of adjacent
cranial nerve to base of skull always
recommended
• Regional LN spread is 15% and elective nodal
irradiation is not standard
• Surgery alone LCR 25-40% +RT 75%-80%
Pleomorphic Adenoma
• Benign tumor – 75% of all parotid epithelial
tumors.
• Surgery is treament of choice
• Multiply recurrent tumors can be treated with RT
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–
–
–
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>3 local recurrences
Large lesion with surgically inadequite margin
Microscopically positive surgical margins
Macroscopic residual disease
Malignant transformation
• 50-60 Gy dose
Minor Salivary Tumors
• Highest concentrations of the glands in the
oral cavity, palate, nasal cavity and paranasal
sinus
• 500-700 Glands
• No glands located in the gingiva or anterior
half of the hard palate
• 50% malignant
• Adenoid cystic is most common malignant
histology seen.
Quiz
• What is the most common tumor of minor
salivary glands
– A. Pleiomorphic Adenoma
– B. Adenoid cystic carcinoma
– C. Mucoepidermoid carcinoma
– D. Squamous cell carcinoma
Quiz
What are the borders of the parotid
gland?
• Superior
• Inferior
• Anterior
• Posterior
• Zyogomatic arch
• Hyoid bone
• Ascending ramus of
mandible
• Mastoid process
Quiz
• The most common parotid tumor is
– A. Pleomorphic adenoma
– B. Mucoepidermoid carcinoma
– C. Adenoid cystic carcinoma
– D. Detroit tigers
Quiz
• Most parotid tumors are ___________
– A. Benign 60%
– B. Benign 80%
– C. Malignant 60%
– D. Malignant 80%
Quiz
• All of the following are true regarding adenoid
cystic carcinoma except?
– A. It rarely spreads to Lymph nodes
– B. It is a common minor salivary tumor
– C. It typically does not involve nerves
– D. 40% develop pulmonary metastasis
Quiz
• Adenoid cystic of parotid s/p parotidectomy
with perineural invasion, what is treatment
field?
– A. Post op bed
– B. Post op bed and BOS
– C. Post op bed and BOS and ipsilateral neck
– D. Post op bed and BOS and bilat neck
Quiz
• What is treatment of choice for cystic
pleomorphic adenoma? After rupture or
residual?
– Superficial parotidectomy. If intraop cystic
rupture, add post op RT
Quiz
How are parotid tumors staged?
•
•
•
•
T1
T2
T3
T4
• ≤ 2cm
• 2-4 cm
• Extraparenchymal, No
VII involvement ± 4-6cm
• >6cm, BOS, CN VII
Quiz
• All of the following are indication for RT in
pleiomorphic adenoma except?
– A. Deep lobe involvement
– B. Large >5cm
– C. Recurrent tumor
– D. Positive margin
Quiz
• What seperates the superficial parotid from
the deep lobe?
– Facial Nerve
Quiz
• Intraparotid lymph node and a single 3cm
neck node what is the most likely primary?
– Skin
– Parotid
Quiz
True/False series. Indication for postop RT for parotid tumors
– Close but clear margin
on benign pleomorphic
adenoma < 3cm
– Adenoid cystic with clear
margin
– High grade
mucopidermoid
– CN VII sacrifice for tumor
close to nerve but not
invading nerve
• False
• True
• True
• False