Aetiology - Environmental Factors Flashcards
What causes cancer?
- All cancers result from mutations in genes resulting in a cell which grows and proliferates at an uncontrolled rate, is unable to repair DNA damage within itself, or refuses to die (apoptosis)
- It takes more than one mutation to turn a cell cancerous
- 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.
What is cancer of the mouth?
Cancer of the mouth
- The general term given to the variety of malignant tumours that develop in the mouth
- Affects the lips, salivary glands, tongue, gum, palate and inside of the cheeks
- Squamous cell carcinoma 90%
- Mouth cancer is the 6th most common cancer worldwide
Head and neck cancers i.e. throat (pharynx), voice box (larynx), salivary glands, nose, nasal, sinuses, lips and skin.
What are some facts and figures about cancer in the UK?
- In 30 years, 400% increase in numbers - 1912 to 8337
- Males twice as likely to suffer than females
- 75% occur in the over 55 yar age group
- Almost 1 new case every hour
- More common than testicular and cervical cancer combined
- 1 person is lost to mouth cancer every 3 hours
What are Risk factors?
- Tobacco
- Alcohol
- Poor diet
- Immunological defect
- Sunlight
- Previous cancer
- Genetic conditions
- Potentially malignant conditions
25% of cases have no known risk factors
How does alcohol consumption increase your risk of cancer?
Smoking and alcohol consumption have a synergistic effect - alcohol act as a solvent for the carcinogens in tobacco - particularly in the sublingual gutter where cancer of the mouth is most commonly found. Alcohol also causes atrophy of the mucosa, thinning it to allow easier diffusion of the carcinogens in tobacco.
- Alcohol is metabolised to acetaldehyde = mutagen and carcinogen
- Alcohol is metabolised in salivary glands, mucosa, oral bacteria hence exposure to acetaldehyde
There is a trend in the incidences of oral cancer and socio-economic deprivation - these areas often have more comorbidities associated with them (smoking and alcohol consumption).
What are Alcohol Recommendations?
Alcohol Recommendations:
Daily limit for males and females: 2 units
Weekly limits for males and females: 14 units
At least 2 days free of alcohol/week
Binge is considered more than 8 units for a male, and more than 6 units for a female
Pregnancy - no safe limit hence do not drink
What is the Tobacco Smoke and Cancer link?
Which is riskier?
Cigarette = Cigar = Pipe Smoking
Effect of increased use?
RR < 10 cig/day = 2.5x compared to a non-smoker
RR <20 cig/day = 5.0x compared to a non-smoker
RR >20 cig/day = 5.5x compared to a non-smoker
Current smoker have a RR of 3.4x compared to a non-smoker
Ex-smokers have a RR of 1.4x compared to a non-smoker
Does quitting reduce risk?
what is in Tabacco smoke?
Contains over 4,000 chemical compounds
- Carbon monoxide
- Arsenic
- Formaldehyde
- Cyanide
- Benzene
- Toluene
- Acrolein
- Acetaldehyde
What happens in lip cancer?
Lip Cancer
- Lower lip more likely than upper lip due to its prominence
- Can appear as a non-healing cold sore
- If not healed in 2-3 weeks, refer
- Cracks, blisters, ulcers
- Association with immunosuppression, UV light exposure and HPV.
Why was the alcohol limit lower for women?
- Women’s bodies have a higher proportion of body fat and less water than men = concentration of alcohol in body water is higher.
- Women have a higher blood alcohol level due to lower gastric ADH activity
- Even if same weight and drink the same, blood alcohol level is 1/3 higher compared to 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
