Oropharynx

Question 1

epidemiology & aetiology

Answer 1

50-70
rare
<1% of all cancer deaths
2.9: 1 [m:f]
poor oral hygiene
smoking: inhalation, risk increases as number and tar content increases
HPV: affects young people and non smokers, improves prognosis
mouthwash, high alcohol content
heavy consumption of alcohol

Question 2

pathology

Answer 2

SCC [75%]
lymphomas
seen to protrude the throat

Question 3

types of spread

Answer 3

direct
lymphatic

Question 4

direct spread

Answer 4

early
affects pillars of forces and soft palate
later invasion of tongue and post pharyngeal wall

Question 5

lymphatic spread

Answer 5

tonsils and pillars: jugulodigastric -> DCC
soft palate: retropharyngeal -> DCC
base of tongue: retropharyngeal -> DCC

Question 6

what is the investigations

Answer 6

full medical history
physical exam: cervical lymphdenopathy, visible signs of primary
radiography: CT/MRI, soft tissue laterals
EUA: under GA for visualisation of the tumour and biopsy

Question 7

staging

Answer 7

T1 = < 2cm
T2 = 2<x< 4cm
T3 = >4cm
T4 = invasion of surrounding structures (pterygoid muscles, mandible, hard palate, deep tongue muscles, larynx)

Question 8

presentation

Answer 8

dysphagia
enlarged lymph nodes (20% are bi)
early
trismus: infiltration deep into para-pharyngeal space

Question 9

what tumours is surgery for

Answer 9

T1/T2

Question 10

what surgery takes place

Answer 10

radical tonsilectomy with partial mandibularectomy with ipsilateral node dissection
tissue deficit made up with a flap repair

Question 11

what types of tumour have RT

Answer 11

SCC and lymphomas

Question 12

what is the dose for SCC

Answer 12

66Gy in 33
55Gy in 20

Question 13

what is the non lateral technique

Answer 13

IMRT
contralateral parotid and spinal cord are OAR
66Gy in 33
54Gy in 33

Question 14

what is the CTV volumes for N0

Answer 14

CTV 1 = ipsilateral level II, bilateral retropharyngeal nodes @ oropharynx
CTV 2 = ipsilateral level III + IV, ipsilateral IB if ant pillar/ oral tongue is involved), contralateral level II-IV

Question 15

what is the CTV volumes for N1-N3

Answer 15

CTV 1 = ipsi level II + involved nodes, bi retropharyngeal nodes at level of oropharynx
CTV 2 = ipsi uninvolved nodes at IB-V, ipsi supraclavicular nodes [selective], con level II-IV, con level IB [selective]

Question 16

describe RT for lymphomas

Answer 16

PTV = waldeyers ring, LN both sides of the neck and base of skull
2 lat fields, covering nasopharynx, ant and post can be used
40Gy in 20

Question 17

soft palate EBRT for T1/T2

Answer 17

TV = GTV + 2cm
small lat parallel opposed fields
primary only
60-66Gy in 30-33

Question 18

soft palate EBRT for T3/T4

Answer 18

bi lateral neck irradiation
same technique as advanced tonsillar

Question 19

side effects

Answer 19

erythema
MDS
mucositis
sore throat
dysphagia
xerostomia
loss of taste
trismus

Question 20

prognosis for T1

Answer 20

60-80

Question 21

prognosis for T2,3,4

Answer 21

30-50

Question 22

why is PET/CT used

Answer 22

early identification of recurrence allow for better outcome and imporved survival

Question 23

what is the PET/CT protocol

Answer 23

MRI/PET-CT = 3 months
PET/CT = 6 months for oropharyngeal, hypopharyngeal and oral SCCs

Question 24

what is PET

Answer 24

it creates 3D images by radiotracers via IV, these are made up of carrier molecules which bond to a radioisotope. Cancerous tissue uptakes glucose, the isotope produces positrons which interact with electrons cause complete annhiliation, which releases two photons. PET detectors measure the photons and the information creates images

Question 25

what radioisotope is used

Answer 25

FDG = modified type of glucose