principles 1: epidemiology

Question 1

cancer is the ____ biggest cause of death in the developed world

Answer 1

2nd

• 1st is cardiovascular disease
• however incidence of cancer is fairly stable / increasing whilst all other major causes are decreasing

Question 2

what regions of the world have the greatest cancer incidence and why?

Answer 2

north america, western europe, australia

• better detection
• increased life expectancy
• screening

Question 3

what are the most common types of cancer in males and females?

Answer 3

men: lung -> liver -> stomach -> colorectum -> oesophagus -> prostate
women: breast -> lung -> colorectum -> cervix -> stomach -> liver -> ovary

Question 4

list some common cancers and their global incidence (per 100,000):

Answer 4

melanoma: 189
prostate: 75
lung: 27
colorectal: 21
oesophageal: 21
liver: 15
bladder: 15
breast: 6
non-hodgkin: 6

Question 5

what does a rapid change in risk of cancer following migration imply?

Answer 5

that lifestyle / environmental factors act late in carcinogenesis

• slow change implies exposures early in life are more relevant
• persistance in risk between generations suggests genetic component important

Question 6

list some hereditary conditions and their associated cancers:

Answer 6

hereditary retinoblastoma: retinoblastoma
xeroderma pigmentosum: skin
Wilm’s tumour: kidney
Li-Fraumeni syndrome: sarcoma, breast, brain, leukaemia
familial adenomatous polypsis: colon, rectum
Paget’s: bone
Fanconi’s aplastic anaemia: leukaemia, liver, skin

Question 7

what are the main risk factors for cancer (and what % risk do they carry)?

Answer 7

smoking (30)   
diet (20-50)   
alcohol (5)     
infection (10-20)    
occupation (3)     
reproductive hormone (10-20)

Question 8

smoking:

Answer 8

• accounts for at least 30% of all cancer deaths
• associated with increased risk for >15 types of cancer
• causes 90% lung cancer deaths in men and 80% in women

Question 9

alcohol:

Answer 9

• all types of alcohol increase risk of cancer in the mouth, larynx, oesophagus & liver
• synergism with tobacco ie smoke + drink > just smoke + just drink

Question 10

what is Parkin’s estimate of preventable cancers in the UK?

Answer 10

45% of cancers in men and 40% in women could be prevented if:

• BMI <25
• > 5 servings fruit/veg each day
• > 23g/day fibre
• <6g/day salt
• > 30mins exercise 5x a week
• breastfed for >6months
• did not smoke

NB reduction/elimination of same risk factors would also lead to significant decrease in cardiovascular & renal & hepatic disease & diabetes

Question 11

what dietary changes can be made to help prevent cancer?

Answer 11

• lean as possible without being underweight
• avoid sugary drinks / high energy foods
• eat variety of f&v & grains
• limit red meats
• limit alcohol
• limit salt intake

Question 12

what percentage of cancer is caused by infectious agents?

Answer 12

16% worldwide (25% in Africa but <10% in europe)

Question 13

what are some common infections that cause cancer?

Answer 13

Epstein-Barr virus: Hodgkin’s & Burkitt’s lymphoma
human papillomavirus: cervix, head&neck
hep B&C: liver
helicobacter pylori: stomach