Transcript Diet and Cancer Part I

Improving The Quality Of Higher Education
In Public Health Sciences
Public Health Nutrition Course
Diet and cancer risk
Part I
Dr. Sahar M. Sabbour
Prof. Public Health, Faculty of
Medicine ASU
[email protected]
HEPHS ll (2013-2015)
Learning objectives
Students should be able to:
a. Describe some key facts about cancer
b. Identify dietary factors that protect against the
risk of cancer.
c. Identify dietary factors that predispose to the
risk of cancer.
d. Determine the classification of carcinogens.
e. Identify scientific evidence that relates diet to
the risk of cancer
Introduction: Nutrition in Health and Disease
Heart
Diseases
Cancer
Stroke
Diabetes
Others
At least four of the 10 leading causes of death – heart diseases,
cancer, stroke and diabetes – are directly related to the way you
eat.
Key facts about cancer
• 8.2 million people worldwide died from cancer in
2012. Globocan 2012, IARC
• 60%of world’s total new annual cases occur in
Africa, Asia and Central and South America.
• 30%of cancers could be prevented.
• It is expected that annual cancer cases will rise
from 14 million in 2012 to 22 million within the
next two decades.
http://www.who.int/mediacentre/factsheets/fs297/en
Key facts about cancer..
• Risk factors include environmental (modifiable) factors
and non-modifiable factors.
• What are the key risk factors that can be avoided?:
–
–
–
–
–
–
–
–
Tobacco use
Being overweight or obese
Unhealthy diet with low fruit and vegetable intake
Lack of physical activity
Alcohol use
Sexually transmitted HPV-infection
Urban air pollution
Indoor smoke from household use of solid fuels.
http://www.who.int/mediacentre/factsheets/fs297/en
Figure : Most Common Cancer Sites Worldwide by Sex, 2008
MALES
http://www.cancer.org/acs/groups/content/@epidemiologysurveilance/documents/document/acspc-027766.pdf
Figure : Most Common Cancer Sites Worldwide by Sex, 2008
FEMALES
Cancer in Africa
Source: GLOBOCAN 2008.
What is a carcinogen?
• Cancer is caused by changes in a cell's DNA
• Some of these changes may be inherited, while others may be
caused by outside exposures, often referred to as environmental
factors.
Environmental factors include a wide range of exposures, such as:
• Lifestyle factors (nutrition, tobacco use, physical activity, etc.)
• Naturally occurring exposures (ultraviolet light, radon gas, infectious
agents, etc.)
• Medical treatments (chemotherapy, radiation, immune systemsuppressing drugs, etc.)
• Workplace exposures
• Household exposures
• Pollution
What is known about Diet and Cancer?
• Diet is one of the modifiable risk factors that can
account for up to 70% of all avoidable cancers.
• Diets contain both inhibitors and enhancers of
carcinogenesis
Activity
• Do you know any dietary factors related to
Cancer risk?
• What is a prudent diet?
What is known about Diet and Cancer
development?
• Dietary Factors
– Estimates are 1/3 of cancers attributed to nutrition
– Cancer Initiators
• Some dietary factors may initiate cancer development
– Cancer Promoters
• Other dietary factors may promote cancer development
once it has started
– Protective Factors
• Still other dietary factors may protect against cancer
development
Diet in relation to cancer risk
• Colon cancer has been associated with consumption of
fat, red meat and high total energy intake, while fiber
intake has a protective effect.
• Breast cancer has been associated with saturated fat
consumption.
• Carcinogens in food items: contamination by
preformed carcinogens like aflatoxins in preserved
humid cereals, nitrites in preserved food, salted fish
and artificial sweeteners, smoked and cured food as
well as charcoal broiled meat.
http://www.who.int/mediacentre/factsheets/fs297/en
Diet in relation to cancer risk..
• High fat diet increase bile production that in
turn stimulates carcinogen forming bacteria
and steroid hormone secretion and increase
susceptibility to cancer colon, breast and
prostate.
• Over nutrition and obesity increase the risk of
endometrial and post menopausal breast
cancer.
http://www.who.int/mediacentre/factsheets/fs297/en
Obesity associated cancers
a risk
factor for
cancer
recurrence
Gall
Bladder
Breast
(after
menopa
use)
Colon
and
rectum
Thyroid
Obesity
Endometrium
Esophagus
Kidney
Pancreas
Prostate
Recent finding
http://www.dietandcancerreport.org/cancer_resource_center/downloads/summary/english.pdf.
Diet in relation to cancer risk..
• Selected protective dietary substances
against cancer include: Ascorbic acid, calcium,
carotenoids, dietary fibres, folic acid, omega-3
fatty acid, phytates, retinoids, selenium and
vitamin E.
• A prudent diet that would be lower in meat
and animal fats, higher in fresh fruits,
vegetables and fibers is protective.
http://www.who.int/mediacentre/factsheets/fs297/en
What are the enhancing and
protective dietary factors in
cancer risk?
Enhancing Nutritional Factors
Cancer Site
High fat diet, Saturated Fats
Colon, Rectum, Breast, Prostate,..
Obesity
Colon, Rectum, esophagus, Breast,
endometrial, Bladder, Prostate*(recently
added, 2014)
Red Meat
Colon, Rectum, Breast
Aflatoxin contaminated food
Liver, stomach
Charcoal cooked food
Colon
Omega 6 polyunsaturated fatty acid
Prostate, Breast, ovaries
Nitrites,
Stomach
Protecting Nutritional Factors
Cancer Site
Omega 3 polyunsaturated fatty acid
Colon, Rectum, Breast
Dietary fibers/…
Colon, Rectum
Folic acid
Cervical, Colon, Rectum
Fruits & Vegetables
GIT cancers, lung, nasopharyngeal
Antioxidants: selenium, Vit A, E, β carotene,. Breast
Strength of the evidence relating food, nutrition and
physical activity with the risk of cancer of the sites
• The Panel of American Institute for Cancer Research,
2007 set a matrix that displays cancer risk as:
Source: World Cancer Research Fund / American Institute for Cancer Research.
Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective. Washington, DC:
AICR, 2007
Example of convincing
deceased risk
Example of convincing
increased risk
• Lactation and breast cancer
premenopause
• Physical activity and
colorectal cancer
• Aflatoxin and liver cancer
• Body fatness and
endometrial cancer
Source: World Cancer Research Fund / American Institute for Cancer Research.
Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective. Washington, DC:
AICR, 2007
Who determines how carcinogens
are classified?
I. International Agency for Research on Cancer
IARC
II. National Toxicology Program
III. Environmental Protection Agency
IV. Other agencies and groups
- National Institute for Occupational Safety
and Health (NIOSH),
- the Food and Drug Administration (FDA),
- and the National Cancer Institute
V. The American Cancer Society's role
International Agency for Research on
Cancer (IARC)
The International Agency for Research on Cancer (IARC) is
part of the World Health Organization (WHO). Its major
goal is to identify causes of cancer. It is the most widely
used system for classifying carcinogens.
In the past 30 years, the IARC has evaluated the cancercausing potential of more than 900 likely candidates,
placing them into one of the following groups:
–
–
–
–
–
Group 1: Carcinogenic to humans
Group 2A: Probably carcinogenic to humans
Group 2B: Possibly carcinogenic to humans
Group 3: Unclassifiable as to carcinogenicity in humans
Group 4: Probably not carcinogenic to humans
Read more
http://www.cancer.org/cancer/cancercauses/othercarcinogens/generalinformationaboutcarcin
ogens/known-and-probable-human-carcinogens
IARC
• Group 1: Carcinogenic to humans :105 type
National Toxicology Program 12th Report on
Carcinogens
• "Known to be human carcinogens“ 56 type
Scientific evidence of diet and
cancer risk
The following slides will show some examples from
previous studies
1. Diet and breast cancer
2. Epidemiologic evidence of the protective effect of
fruit and vegetables on cancer risk
3. Obesity and prostate cancer risk
4. Dairy products and pancreatic cancer risk
Dietary effects on breast-cancer risk in Singapore
1. Diet and breast cancer
Dietary effects on breast-cancer risk in Singapore
• A study of was done in 1991 among 200 Singapore Chinese
women with histologically confirmed breast cancer and 420
matched controls.
• Results: In premenopausal women, high intakes of animal
proteins and red meat were associated with increased risk.
• Decreased risk was associated with high intakes of
polyunsaturated fatty acids (PUFA), beta-carotene, soya
proteins, total soya products, a high PUFA to saturated fatty
acid ratio, and a high proportion of soya to total protein.
Source: Lee HP et al .Dietary effects on breast cancer risk in Singapore. The Lancet, Volume 337, Issue 8751, 1991: 1197–1200
Diet and breast cancer...
• Variables which were significant after adjustment for
each other were:
– Predisposing factor : red meat (p < 0·001)
– Protective factors: PUFA (p=0·02), beta-carotene (p=0·003),
and soya protein (p=0·02)
• The analysis of dietary variables in postmenopausal
women gave uniformly non-significant results.
• Conclusion: Soya products may protect against
breast cancer in younger women. These foods are
rich in phyto-oestrogens.
2. Epidemiologic evidence of the protective effect of fruit
and vegetables on cancer risk.
Source: Riboli E , and Norat T Epidemiologic evidence of the protective effect of fruits and vegetables on cancer risk.
Am J Clin Nutr 2003;78:559S-569S
Epidemiologic evidence of the protective effect of
fruit and vegetables on cancer risk
Source: Riboli E , and Norat T Epidemiologic evidence of the protective effect of fruits and vegetables on cancer risk. Am J
Clin Nutr 2003;78:559S-569S
Meta-analysis of case-control studies on fruit and vegetable intake.
Riboli E , and Norat T ,2003
Summary Results, see next slide
Source: Riboli E , and Norat T Epidemiologic evidence of the protective effect of fruit and vegetables on
cancer risk. Am J Clin Nutr 2003;78:559S-569S
Summary results of the previous article
• The meta-analyses of case-control studies find a
significant risk reduction associated with
vegetables for cancers of the breast, esophagus,
lung, stomach, and colorectum, and with fruit for
cancers of the lung, bladder, stomach,
colorectum, mouth and pharynx, larynx, and
esophagus,
• Meta-analyses of cohort studies only showed the
protective effect of fruit on lung and bladder
cancer.
Source: Riboli E, Norat T Epidemiologic evidence of the protective effect of fruit and
vegetables on cancer risk.. Am J Clin Nutr. 2003 Sep;78(3 Suppl):559S-569S
3. Obesity and prostate cancer risk
• A recent report showed that Obesity is a key
factor linked to increased risk for advanced
prostate cancers.
• Prostate cancer is the second leading cause of
cancer deaths for men in the US. It also adds to
the number of obesity-related cancers, with
prostate cancer becoming the ninth cancer
officially linked to obesity.
Source: Diet, Nutrition, Physical Activity and Prostate Cancer. World Cancer Research Fund
(WCRF), 2014
4. Dairy products and pancreatic cancer
risk: a pooled analysis of 14 cohort studies
• The pooled analysis of the primary data from 14 prospective
cohort studies in 2014 revealed the following:
• No association between total milk intake and pancreatic
cancer risk. Multivariable study-specific hazard ratios (MVHR
= 0.98, 95% CI = 0.82–1.18. Similarly, intakes of low-fat milk,
whole milk, cheese, cottage cheese, yogurt, and ice-cream
were not associated with pancreatic cancer risk. ). Total
calcium intake (MVHR = 0.89, 95% CI = 0.71–1.12 also not
associated with pancreatic cancer risk.
• No associations for dietary and total vitamin D intake and
pancreatic cancer risk.
Source: Genkinger JM et al. Dairy products and pancreatic cancer risk a pooled analysis of 14 cohort
studies Ann Oncol (2014) 25 (6): 1106-1115
4. Dairy products and pancreatic cancer risk: a pooled
analysis of 14 cohort studies.
No association between total milk
intake, other dairy products and
pancreatic cancer risk.
References
•
•
•
•
•
•
•
•
•
•
American Cancer Society. Global Cancer Facts & Figures 2nd Edition. Atlanta: American
Cancer Society; 2011
Lee HP et al. Dietary effects on breast cancer risk in Singapore. The Lancet, Volume 337, Issue
8751, 1991: 1197–1200
Riboli E , and Norat T. Epidemiologic evidence of the protective effect of fruit and vegetables
on cancer risk. Am J Clin Nutr 2003;78:559S-569S
World Cancer Research Fund / American Institute for Cancer Research. Food, Nutrition,
Physical Activity, and the Prevention of Cancer: a Global Perspective. Washington, DC: AICR,
2007
Genkinger JM et al. Dairy products and pancreatic cancer risk a pooled analysis of 14 cohort
studies Ann Oncol (2014) 25 (6): 1106-1115
Diet, Nutrition, Physical Activity and Prostate Cancer. World Cancer Research Fund (WCRF),
2014
http://www.who.int/mediacentre/factsheets/fs297/en
http://www.cancer.org/acs/groups/content/@epidemiologysurveilance/documents/docume
nt/acspc-027766.pdf
http://www.cancer.org/cancer/cancercauses/othercarcinogens/generalinformationaboutcarci
nogens/known-and-probable-human-carcinogens
http://globocan.iarc.fr/Pages/fact_sheets_cancer.aspx