3. Epidemiology of cancer Flashcards
What is incidence and and does this include benign tumours when referring to cancer?
- Number of new cases diagnosed, irrespective of death
* Therefore, this includes benign tumours
What are the main cancers to affect men and women?
- Men - prostate and lung cancer
* Women - breast cancer
What are the 4 biggest killer cancers?
- Breast
- Lung
- Colorectal
- Prostate
How does the incidence of melanoma compare in Australia and China?
Australia:China
200:1
How does the incidence of prostate cancer compare in North America and China?
NA:China
75:1
How can you detect prostate cancer?
PSA levels (measured in a large proportion of men over the age of 55 in high-income countries)
Does early detection of prostate cancer protect people from mortality
Not sure
What causes prostate cancer?
Not sure - may be a genetic component
What are 85-90% of lung cancers due to?
Tobacco smoke
Is it better to use incidence or mortality to measure cancer trends in different countries?
- Incidence
- As mortality rates also reflect access to healthcare and effectiveness of therapies
- There is also a big gap between incidence and mortality in non-lethal cancers
Why is it useful to follow migrants when studying cancer?
- Slow change in risk suggests that exposures early in life are the most relevant
- Rapid change in risk implies that lifestyle/environment factors act late in carcinogenesis
How did stomach and colon cancer change in Japanese people migrating to the USA?
- Japanese that remained in Japan had a very high incidence of stomach cancer
- Incidence of stomach cancer in white Americans is very low
- Japanese that migrated developed a much lower incidence rate
- This was already seen in the first generation
- The opposite occurred with colon cancer
What is likely to cause stomach and colon cancer?
Environmental factors
• Diet likely to be involved
• Infections also likely to have an effect e.g. H. pylori
What proportion of cancers are inheritable (to pre-disposition)?
5-10%
How are incidence and mortality rates of cancer changing in high-income countries?
- Incidence plateauing
* Mortality decreasing
How is total burden changing?
Increasing due to demographic changes (ageing populations, increasing size) and Westernisation of lifestyles
How does the prognosis of breast cancer differ in African-American women compared to White women?
Worse prognosis in all stages
What are the different estimations of the causes of cancer?
- Smoking (30%)
- Diet (20-50%)
- Alcohol (6%)
- Infection (10-20%)
- Occupation and reproductive hormones
What proportion of cancers are attributable to known risk factors?
40%
How many cancers is smoking associated with the increased risk of having?
At least 15 types
How can we decrease the colon cancer risk with our diet
Increase fibre intake
Which cancers does alcohol increase the risk of having?
- Oral
- Pharynx
- Larynx
- Oesophagus
- Liver
How does anthropometry play a part in the risk of cancer?
Increased BMI and obesity associated with:
• breast cancer (particularly post-menopausal)
• prostate cancer
• endometrial cancer
What are the World Cancer Research Fund guidelines for dietary prevention?
- Be as lean as possible without becoming underweight
- Be physically active for at least 30 minutes every day
- Avoid sugary drinks and limit consumption of energy-dense foods
- Eat more of a variety of vegetables, fruits, wholegrains, and pulses such as beans
- Limit consumption of red meats and avoid processed meats
- If consumed at all, limit alcoholic drinks to 2 for men and 1 for women a day
- Limit consumption of salty foods and foods processed with salt (sodium)
- Don’t use supplements to protect against cancer
What is a ‘Western lifestyle’?
- Energy dense diet, rich in fat, refined carbohydrates and animal protein
- Low physical activity
- Smoking and drinking
What are the consequences of a Western lifestyle?
- Greater adult height
- Early menarche (first occurrence of menstruation)
- Obesity
- Diabetes
- CVD
- Hypertension
What proportion of cancers are likely to be caused by infectious agents in Africa and Europe?
- 25% in Africa
* <10% in Europe