8. OSCC Flashcards
Definition of neoplasia?
An independent, uncoordinated new growth of tissue, capable of unlimited proliferation which does not regress after removal of the stimulus which produced the lesion.
What 5 features do tumour cells have that allows them to reproduce uncontrollably?
Limitless cell replication
Self-sufficient growth
Avoidance of apoptosis
Insensitivity to anti-growth signals
Sustained angiogenesis
What are oncogenes derived from and what do they code for?
Derived from proto-oncogenes in normal cells
Code for growth promoting factors
They are overexpressed in cancer cells
What are examples of oncogenes?
EGFR/C-erb1
ras family
c-myc
int-2
hst-1
What is a tumour suppressor gene and what does it do?
Present in normal cells, but mutated (non-fully functional) in cancer cells
It blocks division in the G1 phase
Examples of tumour suppressor genes?
P16
P53
Rb
How do tumour cells enlarge telomeres?
They ave a telomerase enzyme which enlarges the telomeres again, increasing the hyphic limit
What is Knudson’s two hit theory of cancer causation?
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.
What are some examples of chromosomal instability?
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
What people does HPV in head and neck cancer most affect?
Younger people, non-smokers, non-drinkers, immunosuppressed, Fanconi anaemia
Where is HPV in head and neck cancer affect most?
Lingual and palatine tonsils
What is the histology of HPV in head and neck cancer?
Basaloid appearance, poorly differentiated
How can immunology cause cancer?
Immunodeficiency, immunosuppression, chronic infections like syphilis and candidosis
What have cancer patients revealed with immunology?
Lymphocyte enhanced cytotoxicity
Macrophage enhanced phagocytosis
What is circumstantial evidence that immunology is linked to cancer?
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
What is Goldberg’s tissue stress theory?
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.
What does UV radiation most commonly cause?
Lip carcinoma
More common in lower lip than upper
Associated with outdoor occupations
Why is lip cancer less common in dark skin races?
It is protected by melanin
What may occur before lip carcinoma?
Solar keratosis
What are 6 examples of chemical agents for cancer?
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
What is tobacco composed of that is linked to cancer?
Aromatic hydrocarbons, nitrosamines
How does tobacco increase the risk?
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
How does alcohol increase the risk?
Ethanol is not a carcinogen
Alcohol dissolves carcinogens making it easier to enter the epithelium and target the basal cells.
What is the association between drinking and smoking?
Synergistic effect
Impaired metabolism in heavy drinkers which allows circulating carcinogens to circulate in the body for much longer.
What are 2 examples of primary sideropaenic anaemia?
Plummer-Vinson
Patterson-Kelly syndrome
What does primary sideropaenic anaemia increase the risk of?
Oesophageal, pharyngeal and oral cancer
What is the role of vitamin A?
Maintains the epithelium
Antioxidant- also vitamin C and E
What is the presentation of SCC?
Usually asymptomatic
White/red/speckled patch
Small exophytic growth
Ulceration with ragged edge
Heaped up border
Indurated
Necrotic floor
Granular base
What can OSCC be associated with?
Failure to heal
tooth mobility
Pain
Paraesthesia
Dysphagia
Regional lymph nodes
What is the site distribution of OSCC?
Tongue
Lip
Floor of mouth
Gingiva- lower then upper
Cheek
Palate
