Oropharynx/Hypopharynx/nasopharynx/oralcavity Flashcards
Anatomy of the oral cavity (subdivisions)
Extends from the skin-vermilion junction of the lip to the posterior border of the hard palate.
Subdivisions include:
- anterior two/thirds of the tongue
- lip
- buccal mucosa
- retromolar trigone
- floor of the mouth
- hard palate
Clinical presentation of oral cancer
- poor oral/dental hygiene
- Plummer-Vinson syndrome (iron-deficiency anemia) is considered a risk factor in women
- leukoplakia and erythroplasia are considered serious pathologic problems.
- most oral cavity cancers present as non-healing lesions
- pain may be associated with advanced disease
Radiation therapy for oral cavity
Local regional control depends on highly accurate treatment with a sharp dose gradient to reduce the dose to surrounding healthy tissue.
The gross disease will receive a dose of approximately 70Gy
Volumes at high risk for microscopic disease and high-risk lymph nodes receive a dose of 64Gy
Volumes of low risk such as contralateral neck and elective lymph nodes should receive 60Gy
Electron treatment can be used for treatment areas such as lip or superficial tumours.
The natural history of oral cancer
- oral cavity cancers have the lowest incidence (except glottic tumours) of nodal spread for all head and neck cancers
Pharynx anatomy
Subdivided into three sections:
- oropharynx
- nasopharynx
- hypopharynx
Oropharynx anatomy
Consists of the base of the tongue, the tonsils, the soft palate and the oropharyngeal wall.
Situated between C3 and the axis
Located behind the mouth from the soft palate above to the hyoid bone
Anatomy of the hypopharynx
Composed of the pyriform sinuses, post-cricoid and lower posterior pharyngeal walls.
Anatomically situated between C3 and C6.
Cricoid cartilage represents the inferior border and the epiglottis the superior border.
Epidemiology for hypopharynx cancer
Male to female rate ranges from 5:1 to 7:1 for pyriform sinus cancer
Male to female rate ranges from 3:1 to 4:1 for pharyngeal wall cancer
Postcricoid cancers are typically female
Signs and symptoms of pharynx cancer
Sore throat and pain when swallowing is most common.
Otalagia (ear pain) can also occur
Enlargement of the cervical nodes
Common presenting symptoms of hypopharynx cancer
- sore throat
- odynophagia
- 25% present with a neck mass
Dysphagia and weight loss are more common in advanced diseases.
Etiology of oral cavity or oropharynx cancers
Growing subpopulation between 20 and 50 due to the rising incidence of HPV-related head and neck cancers.
50-60-year-old with a long history of smoke &/or alcohol consumption
- more than 20 cigs/day increase 6-fold risk
- 6oz liquor day increase 10-fold risk
Chewing betel nut, smokeless tobacco-related to buccal mucosa, lip and floor of mouth (more common in Asia)
Highest site of incidence for hypopharynx cancer
Pyriform sinus
Radiation therapy for the oropharynx region
Early T1 and T2 lesions are treatable with EBRT alone
Large volumes are required T3 and T4 lesions that encompass the cervical and supraclavicular nodes.
Stage III and IV cancers are treated with definitive radiation and concurrent chemotherapy
Treatment of hypopharynx cancer
Typically an advanced disease. With high rates of nodal metastasis for pyriform sinus cancers.
Rare T1 and T2 lesions can be treated with radiation therapy or surgery and are curable.
T2-T4 lesions are more common and are not candidates for laryngeal preservation surgery. Most patients receive combined radical surgery and radiation therapy. Large radiation therapy fields are needed to treat pyriform sinus as well as cervical lymph nodes.
Tumours of the posterior pharyngeal wall are unresectable and are treated with large field RT. That includes the entire pharynx, upper cervical esophagus, extending superiorly to the nasopharynx vault and local lymph nodes.
Radiation therapy for the pharynx region
Radiation therapy has become the standard of treatment for oropharynx cancer.
As cure rates increase the concern for treatment-related issues such as xerostomia and mandible necrosis has become important issues.
IMRT helps to reduce the dose to organs at risk and help with locoregional control
Pathology of pharynx cancers
Predominantly SCC (90%)
Lymphoepilioma may occur in the tonsil and the base of the tongue
Negative prognosis indicators for all head and neck cancers
Tumours that cross the midline
Invasion of lamina propria or submucosa
Poorly differentiated
Non-SCC
Fixed lymph nodes
Cranial nerve involvement
Vascular invasion
Nasopharynx anatomy
Includes the:
- posterosuperior pharyngeal wall
- lateral pharyngeal wall
- eustachian tube orifice
- adenoids
Location: lies on a line from the zygomatic arch to the external auditory meatus extending inferiorly to the mastoid tip. Lies behind the nasal cavity and above the level of the soft palate.
Epidemiology of nasopharynx cancer
The age distribution is bimodal with a small peak in adolescence and young adulthood but with a large peak between 50-70 years of age.
Uncommon in white populations (accounts for only 2% of cases)
The high incidence rate in southern Chinese (57%) and middle eastern countries may be attributed to nitrosamines in alsed fish.
Lymph spread from the nasopharynx
- Retropharyngeal
- upper jugular
- spinal accessory
Etiology of nasopharynx cancer
Not associated with tobacco
Associated with EBV
Pathology of nasopharynx cancer
The tendency toward poor differentiation and unusual growth patterns.
Type 1: keratinizing SCC (20% of cases)
Type 2: non-keratinizing SCC (10% of cases)
Type 3: lymphepithelioma (poorly differentiated carcinomas, 70% of cases)
Radiation therapy for nasopharynx cancer
Due to the high likelihood of involvement of the cervical nodes and local spread radiation fields are typically large.
Concern due to a high number of OAR’s in the area makes it difficult to provide the high dose needed to control the disease.
The CTV should include the GTV as well as the high-risk nodes including:
- upper deep jugular nodes
- submandibular nodes
- subdigastric nodes
- mid jugular nodes
- posterior cervical nodes
- retropharyngeal nodes
* adjuvant chemotherapy seems to improve both local control and survival. Chemotherapy should be used with stage III and IV tumours.
Location of metastasis for nasopharynx cancer
25% chance of bloodborne metastasis
In those with bilateral cervical nodes 40-70% chance of distant metastasis.
Bone, lung and liver being most common.
Nasopharynx T1 stage
Tumour confined to nasopharynx or extends to oropharynx or nasal cavity without parapharyngeal extension.
Nasopharynx T2 stage
Tumour involves parapharyngeal extension
Nasopharynx T3 stage
Tumour involves bony structures of skull base or paranasal sinuses
Nasopharynx T4 stage
Tumour with intracranial extension or involvement of cranial nerves, hypopharynx, or orbit, or with extension to the infratemporal fossa
Hypopharynx T1 stage
Tumour limited to one subsite of the hypopharynx or 2cm or less in greatest dimension
Hypopharynx T2 stage
Tumour invades more than one subsite of the hypopharynx or an adjacent site or measures more than 2cm but not more than 4cm in greatest dimension without fixation of the hemilarynx.
Hypopharynx T3 stage
Tumour more than 4cm in greatest dimension or with fixation of hemilarynx or extension into the esophagus.
Hypopharynx T4 stages
T4a: moderately advanced local disease.
- tumour invades thyroid/cricoid cartilage, hyoid bone, thyroid gland
T4b: very advanced local disease
- Tumour invades prevertebral fascia, encases carotid artery, or involves mediastinal structures.
Oropharynx T1 stage
Tumour 2cm or less in dimension
Oropharynx T2 stage
Tumour more then 2cm but less then 4cm in the greatest dimension
Oropharynx T3 stage
Tumour more than 4cm in greatest dimension or extension to the lingual surface of glottis
Oropharynx T4 stages
T4a: Moderately advanced local disease
- tumour invades larynx, extrinsic muscle of tongue, hard palate or mandible
T4b: very advanced local disease
- tumour invades the lateral nasopharynx, skull base or encases carotid artery.
Nasopharynx N1 stage
Unilateral metastasis in lymph nodes, 6cm or less in greatest dimension, above the supraclavicular fossa or unilateral or bilateral retropharyngeal nodes 6cm or less in greatest dimension.
Nasopharynx N2 stage
Bilateral metastasis in lymph nodes <6cm in dimension above supraclavicular fossa
Nasopharynx N3 stages
N3: metastasis in lymph nodes >6cm in dimension or extension into the supraclavicular fossa
N3a: >6cm in greatest dimension
N3b: extension into the supraclavicular fossa
Oropharynx and hypopharynx N1 stage
Metastasis in a single ipsilateral lymph node 3cm or less in greatest dimension
Oropharynx and hypopharynx N2 stage
N2a: metastasis in a single lymph node more than 3cm but less than 6cm in greatest dimension
N2b: metastasis in multiple ipsilateral lymph nodes, none more than 6cm in greatest dimension
N2c: metastasis in bilateral or contralateral lymph nodes, none more then 6cm in greatest dimension
Oropharynx and hypopharynx N3 stage
Metastasis in a lymph node more then 6cm in greatest dimension
