8. OSCC

Question 1

Definition of neoplasia?

Answer 1

An independent, uncoordinated new growth of tissue, capable of unlimited proliferation which does not regress after removal of the stimulus which produced the lesion.

Question 2

What 5 features do tumour cells have that allows them to reproduce uncontrollably?

Answer 2

Limitless cell replication
Self-sufficient growth
Avoidance of apoptosis
Insensitivity to anti-growth signals
Sustained angiogenesis

Question 3

What are oncogenes derived from and what do they code for?

Answer 3

Derived from proto-oncogenes in normal cells
Code for growth promoting factors
They are overexpressed in cancer cells

Question 4

What are examples of oncogenes?

Answer 4

EGFR/C-erb1
ras family
c-myc
int-2
hst-1

Question 5

What is a tumour suppressor gene and what does it do?

Answer 5

Present in normal cells, but mutated (non-fully functional) in cancer cells
It blocks division in the G1 phase

Question 6

Examples of tumour suppressor genes?

Answer 6

P16
P53
Rb

Question 7

How do tumour cells enlarge telomeres?

Answer 7

They ave a telomerase enzyme which enlarges the telomeres again, increasing the hyphic limit

Question 8

What is Knudson’s two hit theory of cancer causation?

Answer 8

Sporadic vs hereditary
In the case of hereditary, you only need one rare event to create 2 hits.
In the case of sporadic, you need 2 rare events.
Inheriting the 1st hit in the Rb gene increases the risk of developing the tumour by 100000 times.

Question 9

What are some examples of chromosomal instability?

Answer 9

Imbalance in number of chromosomes per cell-aneuploidy
Enhanced loss of heterozygosity
Loss or gain of whole chromosomes can upset checks and balances that maintain normal cell growth

Question 10

What people does HPV in head and neck cancer most affect?

Answer 10

Younger people, non-smokers, non-drinkers, immunosuppressed, Fanconi anaemia

Question 11

Where is HPV in head and neck cancer affect most?

Answer 11

Lingual and palatine tonsils

Question 12

What is the histology of HPV in head and neck cancer?

Answer 12

Basaloid appearance, poorly differentiated

Question 13

How can immunology cause cancer?

Answer 13

Immunodeficiency, immunosuppression, chronic infections like syphilis and candidosis

Question 14

What have cancer patients revealed with immunology?

Answer 14

Lymphocyte enhanced cytotoxicity
Macrophage enhanced phagocytosis

Question 15

What is circumstantial evidence that immunology is linked to cancer?

Answer 15

Spontaneous regression
Primary regression after sub-lethal chemotherapy
Metastasis regression after excision of primary
Mononuclear infiltration of tumours
Increased tumours with ageing, immuno-suppression and deficiency

Question 16

What is Goldberg’s tissue stress theory?

Answer 16

Repetitive ulceration occurs because the attachment of epithelium to the basement membrane is faulty. This causes loss of cellular memory. This means there is less cellular differentiation, which causes tumour promotion.
Due to ulceration, there is lots of cytokines being released in that area which are like fibroblast growth factors.
Some genes may be disbalanced such as Fas gene (which controls apoptosis) mutations which occur in patient’s who have burns, so apoptosis does not occur when it should.

Question 17

What does UV radiation most commonly cause?

Answer 17

Lip carcinoma
More common in lower lip than upper
Associated with outdoor occupations

Question 18

Why is lip cancer less common in dark skin races?

Answer 18

It is protected by melanin

Question 19

What may occur before lip carcinoma?

Answer 19

Solar keratosis

Question 20

What are 6 examples of chemical agents for cancer?

Answer 20

Tobacco
Alcohol
Areca nut
Diet poor in vegetables and fruit
Mate drinking- pumpkin hollowed and drink tea in it from metal straw
Indoor pollution- exposure to fossil fuels, volatile compounds/cooks

Question 21

What is tobacco composed of that is linked to cancer?

Answer 21

Aromatic hydrocarbons, nitrosamines

Question 22

How does tobacco increase the risk?

Answer 22

Those who smoke more than 40 a day have 10-20 times higher risk of cancer than non-smokers
The average smoker has 3 times higher risk
Ex smoker relative risk falls 10 years after they stop

Question 23

How does alcohol increase the risk?

Answer 23

Ethanol is not a carcinogen
Alcohol dissolves carcinogens making it easier to enter the epithelium and target the basal cells.

Question 24

What is the association between drinking and smoking?

Answer 24

Synergistic effect
Impaired metabolism in heavy drinkers which allows circulating carcinogens to circulate in the body for much longer.

Question 25

What are 2 examples of primary sideropaenic anaemia?

Answer 25

Plummer-Vinson
Patterson-Kelly syndrome

Question 26

What does primary sideropaenic anaemia increase the risk of?

Answer 26

Oesophageal, pharyngeal and oral cancer

Question 27

What is the role of vitamin A?

Answer 27

Maintains the epithelium
Antioxidant- also vitamin C and E

Question 28

What is the presentation of SCC?

Answer 28

Usually asymptomatic
White/red/speckled patch
Small exophytic growth
Ulceration with ragged edge
Heaped up border
Indurated
Necrotic floor
Granular base

Question 29

What can OSCC be associated with?

Answer 29

Failure to heal
tooth mobility
Pain
Paraesthesia
Dysphagia
Regional lymph nodes

Question 30

What is the site distribution of OSCC?

Answer 30

Tongue
Lip
Floor of mouth
Gingiva- lower then upper
Cheek
Palate