Oral cancer aetiology environmental factors Flashcards
What causes cancer
- Mutations in genes resulting in a cell which grows an proliferates at an uncontrolled rate, is unable to repair DNA damage within itself or refuses to die (apoptosis)
-Multiple mutations are required to make a cell cancerous
Describe neoplastic cell
- Specific classes of genes must be mutated several times to result in a neoplastic cell, which then grows in an uncontrolled manner
- When a cell does become mutated it is capable of passing on the mutations to all of its progeny when it divides
- genetic errors can be inherited, be caused by viruses, or develop as a result of exposure to chemicals or radiation
Describe oral cancer
-variety of malignant tumours that develop in the mouth, (oral cavity)
- affects the lips, salivary glands, tongue, gums, palate and inside of the cheeks
- Squamous cell carcinoma 90%
- head and neck cancers i.e. throat (pharynx), voice box (larynx), salivary glands, nose, nasal, sinuses, lips and skin
describe anterior part and posterior part of tongue
- anterior part of tongue is referred to as mouth cancer
- posterior part of the tongue is known as oropharynx
List the risk factors in order of most damaging
- Tobacco
- Alcohol
- Poor diet/obesity
- Immunological defect
- Sunlight
- Previous cancer
- Genetic conditions
- Potentially malignant conditions
- 25% of cases have no known risk factors
Why does smoking cause cancer?
- Cancer causing chemicals:
Tar, arsenic, polycyclic aromatic hydrocarbons e.g. Benzopyrene (PAH),
Nitrosamines, acrolein (mutagen, carcinogen) - Other poisons:
Hydrogen cyanide, CO, Ammonia
List the cultural habits associated with increased risk
- Betel nut
- seed of the areca catechu
- Piper betel leaf
- Slaked line = calcium hydroxide
- spices
- Tobacco
Describe the pathogenesis
- Poorly understood
- Arecoline an alkaloid in the nut has been shown to stimulate collagen synthesis by 170%
- Tannins present in the nut increase the resistance of collagen degradation
- DNA damage
- Lime can release reactive oxygen species from extracts of betel nut
Give examples of other forms of tobacco
- Reverse smoking
- Bidi smoking
- Tobacco chewing
- Qat somalia
- Water pipe
Describe alcohol and oral cancer
= Alcohol is metabolised t o acetaldehyde = mutagen and carcinogen
- alcohol is metabolised in salivary glands, mucosa, oral bacteria hence exposure to acetaldehyde
What are sources of acetaldehyde ?
- Alcohol metabolism
ADH in oral mucosa, salivary glands, oral microflora - Tobacco smoke
- Bacteria associated with poor OH?
- Food?
Describe alcohol recommendations
- Daily limit F: 2units, M: 2 units
- Weekly limits F: 14 units, M: 14 units
- At least 2 days free of alcohol/week
- Binge M more then 8 units F more than 6 units
- Pregnancy: no safe limit hence don’t drink
Why was the alcohol limit lower for women?
- Women’s bodies have higher proportion of body fat and less water than men = conc. of alcohol in body water is higher
- Women have higher blood alcohol levels due to lower gastric ADH activity
- Even if same weight + drink the same, blood alcohol level 1/3 increase cf Men - Will take 1/3 longer to eliminate the alcohol
- Alcohol dependence and related medical problems, such as brain and liver damage, progress more rapidly in women than in men
What is UV light associated with?
Lip cancer
- lower lip
- cracks, blisters, ulcers
- early presentation
- association with immunosuppression
