Diet and Cancer Flashcards
Origins of hypothesis linking diet with cancer risk
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
Trends in age-standardised incidence of cancer in men in UK
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%)
Trends in age-standardised incidence of cancer in women in UK
Breast rising since 1970 (31% incidence 2015)
Colorectal remained same (11%)
Lung rising slowly since 1970 (12%)
Ovary slight rise since 1970
Effects of migration on cancer incidence/ mortality
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
Human studies
Ecological studies
Case-control studies
Prospective cohort studies
Randomised controlled trials
Investigating mechanisms
In vitro Exfoliated cells Cells in culture Animal models Human studies
Effects over lifespan
Diet, smoking, infection, exercise, medication have an effect towards cancer
Food, Nutrition, Physical Activity, and the prevention of Cancer: A Global Perspective 2007
5 years, meeting every 6m
>6000 papers considered, 20 SLR groups
Body fatness and cancer
- Post menopausal breast
- Endometrial
- Colorectal
- Oesophageal
- Pancreas
- Kidney
BMI and breast cancer
Continuous update panel (CUP)
10 new studies - overall, 13% increased risk/5kg/m^2
Obesity and colon cancer
CUP: 22 new cohort studies
Overall, 10% increased risk/5kg/m^2
Mechanisms linking obesity and endometrial cancer
Oestrogens
Obesity may be the most important of all nutritional risk factors for cancer
Many sites
Men and women
Preventable
Modifiable
WCRF recommendations for individuals
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
Foods and drinks that promote weight
gain: WCRF Recommendations for
in adulthood Individuals
Consume energy-dense foods sparingly
Avoid sugary drinks
Consume ‘fast foods’ sparingly, if at all
Physical activity and cancer
Convincing: colon
Probably: postmenopausal breast cancer, endometrial
CUP - 3% reduced for CRC, 8% reduced risk for colon
Physical activity: WCRF Recommendations for Individuals
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
Plant foods and cancer
Probably protective: Mouth Pharynx Larynx Oesophageal Lung Stomach Pancreatic Prostate Colorectal (10% decreased risk/ 10g dietary fibre per day)
Plant foods
WCRF recommendation for individuals
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
Animal foods and cancer
Convincing: colorectal cancer (red and processed meat)
-17% increased risk/ 100g red meat per week)
Animal foods: WCRF
recommendation for individuals
Consume <500g red meat per week and very little (if any) processed
Alcohol and cancer
Convincing increases risk:
- mouth
- larynx
- oesophagus
- colorectal
- breast
Alcoholic drinks: WCRF
recommendation for individuals
Limit consumption to no more than two
drinks per day for men and one drink for women
Mechanisms for the role of diet
in carcinogenesis
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
