Diet and Cancer

Question 1

Origins of hypothesis linking diet with cancer risk

Answer 1

Yong-He Yan (960-1279 AD) thought poor diet was cause of oesophageal cancer
Wiseman (1676) thought cancer might be caused by too much meat and salt in diet
Lambe (1815) suggested diet rich in meat might cause cancer
Bennett (1849) recommended diet low in fatty foods to < cancer risk

Question 2

Trends in age-standardised incidence of cancer in men in UK

Answer 2

Lung gone down since 1985 (13% incidence in 2015)
Prostate rising since 1970 (26%)
Stomach down slightly since 1970
Colorectal up slightly since 1970 (13%)

Question 3

Trends in age-standardised incidence of cancer in women in UK

Answer 3

Breast rising since 1970 (31% incidence 2015)
Colorectal remained same (11%)
Lung rising slowly since 1970 (12%)
Ovary slight rise since 1970

Question 4

Effects of migration on cancer incidence/ mortality

Answer 4

European migrants to Australia during 1950-1975 experienced more breast cancer mortality
Asian migrants to USA experienced higher incidence of colorectal cancer than foreign-born Japanese men and 60% higher than US-born white men
Strong evidence of environmental and behavioural influences on aetiology of cancers
Increased risk on duration of residence
One of more exposures or characteristics that differ between migrants and descendents affect development of colorectal cancer

Question 5

Human studies

Answer 5

Ecological studies
Case-control studies
Prospective cohort studies
Randomised controlled trials

Question 6

Investigating mechanisms

Answer 6

In vitro
Exfoliated cells
Cells in culture
Animal models
Human studies

Question 7

Effects over lifespan

Answer 7

Diet, smoking, infection, exercise, medication have an effect towards cancer

Question 8

Food, Nutrition, Physical Activity, and the prevention of Cancer: A Global Perspective 2007

Answer 8

5 years, meeting every 6m

>6000 papers considered, 20 SLR groups

Question 9

Body fatness and cancer

Answer 9

• Post menopausal breast
• Endometrial
• Colorectal
• Oesophageal
• Pancreas
• Kidney

Question 10

BMI and breast cancer

Answer 10

Continuous update panel (CUP)

10 new studies - overall, 13% increased risk/5kg/m^2

Question 11

Obesity and colon cancer

Answer 11

CUP: 22 new cohort studies

Overall, 10% increased risk/5kg/m^2

Question 12

Mechanisms linking obesity and endometrial cancer

Answer 12

Oestrogens

Question 13

Obesity may be the most important of all nutritional risk factors for cancer

Answer 13

Many sites
Men and women
Preventable
Modifiable

Question 14

WCRF recommendations for individuals

Answer 14

Be as lean as possible within normal range of body weight
Through childhood and adolescence project toward lower end of normal body weight (BMI 18.5)
Throughout adulthood stay within normal range (BMI<25)
Avoid weight gain and increases in waist circumference

Question 15

Foods and drinks that promote weight
gain: WCRF Recommendations for
in adulthood Individuals

Answer 15

Consume energy-dense foods sparingly
Avoid sugary drinks
Consume ‘fast foods’ sparingly, if at all

Question 16

Physical activity and cancer

Answer 16

Convincing: colon
Probably: postmenopausal breast cancer, endometrial
CUP - 3% reduced for CRC, 8% reduced risk for colon

Question 17

Physical activity: WCRF Recommendations for Individuals

Answer 17

Be moderately physically active, e.g. brisk walking,
For at least 30mins/ day
As fitness improves, aim for 60 mins or more of moderate,
or for 30 mins or more of vigorous physical activity / day
Limit sedentary habits e.g. watching television

Question 18

Plant foods and cancer

Answer 18

Probably protective:
Mouth 
Pharynx 
Larynx
Oesophageal
Lung 
Stomach
Pancreatic
Prostate
Colorectal (10% decreased risk/ 10g dietary fibre per day)

Question 19

Plant foods

WCRF recommendation for individuals

Answer 19

Eat at least 5 portions or a variety of non-starchy
vegetables and fruits daily
Eat relatively unprocessed cereals and pulses with
every meal
Limit refined starchy foods

Question 20

Animal foods and cancer

Answer 20

Convincing: colorectal cancer (red and processed meat)

-17% increased risk/ 100g red meat per week)

Question 21

Animal foods: WCRF

recommendation for individuals

Answer 21

Consume <500g red meat per week and very little (if any) processed

Question 22

Alcohol and cancer

Answer 22

Convincing increases risk:

• mouth
• larynx
• oesophagus
• colorectal
• breast

Question 23

Alcoholic drinks: WCRF

recommendation for individuals

Answer 23

Limit consumption to no more than two

drinks per day for men and one drink for women

Question 24

Mechanisms for the role of diet

in carcinogenesis

Answer 24

Diet may influence the chance of developing
cancer by:
– Increasing exposure to chemical
carcinogens (Chinese style salted fish)
– Facilitating action of viruses (HPV)
– Influencing effects of hormones (adiposity
and oestrogen, fibre and steroids)
– Minimising oxidant and other damage to DNA
– Influencing DNA repair genes