Semestereröffnungsveranstaltung für das WS 09/10
Masterstudiengänge Public Health und Epidemiologie
München, den 19. Oktober 2009
Adiposity and cancer:
an epidemiologic challenge
Michael Leitzmann MD DrPH
Department of Epidemiology and Preventive Medicine
University of Regensburg
University of Regensburg
Department of Epidemiology and
Preventive Medicine at the
University of Regensburg
Map of Germany
Regensburg
Schools of public health in Germany
Berlin
Bielefeld
Bremen
Dresden
Düsseldorf
Hannover
Heidelberg
Mainz
München
Educational background of
public health students in Munich
• Medicine
• Natural sciences
• Economics
• Pharmacology
• Psychology
• Sociology
• Educational science
• Exercise science
• Nutrition
Why earn a degree in
public health?
• You care for the health of our populations,
not just at the individual level
• You enjoy the satisfaction of helping others
to improve their quality of life
• You enjoys crunching numbers, conducting
research, and working with people
What is public health?
• Public health is
about understanding
and improving
people‘s lives so
that all of us can be
as healthy as
possible
www.britannica.com
Major public health issues
•
•
•
•
•
•
•
•
Diseases
Air quality
Consequences of catastrophic events
Health disparities
Water and food safety
Access to health care
Health behaviors
Injury prevention
What is epidemiology?
• Fundamental medical science that focuses
on the distribution and determinants of
disease frequency in human populations
• Epidemiologists examine patterns of illness
in groups of people and then try to learn why
certain individuals develop a particular
disease whereas other persons do not
Definition of epidemiology
Greek origin:
epi = upon (as in epidermis)
demos = the people (as in demography)
ology = to speak of, to study
Interdisciplinary nature of epidemiology
www.uni-ulm.de/med/med-epidemiologie/forschung-in-der-epidemiologie.html
John Snow - father of modern
epidemiology
• London family doctor, astute
clinician, pioneer anaesthetist
• Used rigorous logic to work
out and publish the definitive
monograph “On the Mode of
Communication of Cholera” in
1855
• This was 30 years before
Robert Koch discovered Vibrio
cholerae, the causative
organism
John Snow
(1813–1858)
John Snow and the cholera epidemic
• In London at that time, a person obtained
water by signing up with one of the water
supply companies
• The intake for the water companies was a
polluted part of Thames river
• One of the companies (Lambert Company)
shifted its water intake upstream in the
Thames to a less polluted part of the river
but the others didn’t
Cholera death rates
Water supply
Cholera deaths
per 10,000 homes
Southwalk & Vauxhall
315
Lambert
38
Other districts in London
56
Map of cholera outbreak
The Broad Street pump
Following Snow's
advice to remove the
handle of the Broad
Street Pump that
supplied water to this
neighbourhood, the
epidemic was
contained
Modern epidemiology
Exposure
Black box
Disease
Modern epidemiology
Nutritional
epidemiology
Cancer
epidemiology
Occupational
epidemiology
Genetic
epidemiology
Exposure
Black box
Pharmacoepidemiology
Disease
Infectious disease
epidemiology
Environmental
epidemiology
Examples of landmark modern
epidemiological research
• Smoking and lung cancer (Doll and Hill, 1950‘s)
• Aromatic amines and bladder cancer (Case et al, 1954)
• Folic acid and neural tube defects (Medical Research
Council Vitamin Study, 1991)
The global obesity “epidemic“
• In 2005, approximately 1.6 billion adults were
overweight and at least 400 million adults
were obese globally
• By 2015, approximately 2.3 billion adults will
be overweight and more than 700 million will
be obese globally
• Adiposity is increasing dramatically in both
developed and developing countries
WHO 2005
Classification of BMI
BMI
(kg/m2)
WHO
Classification
Popular
Description
< 18.5
Underweight
Thin
18.5 - 24.9
Normal weight
Normal
25.0 - 29.9
Grade 1 overweight
Overweight
30.0 - 39.9
Grade 2 overweight
Obesity
40.0 +
Grade 3 overweight
Morbid obesity
WHO 1995
Projected trend in obesity prevalence
in Europe
International Association for the Study of Obesity and International Obesity Task Force, 2005
Obesity trends among US adults
1987, 1997, 2007
1987
1997
2007
No Data
<10%
10%–14%
15%–19%
20%–24%
25%–29%
≥30%
Childhood adiposity
Global population,
by age and sex (2002)
US Census Bureau. Global Population Profile 2002
World population growth 1950-2050
Billions
1
United Nations 2008
Adiposity and major chronic diseases
Willett et al 1999
Global projections for diabetes
prevalence in 2007 and 2025 (millions)
Diabetes Atlas, Third Edition, 2006
Obesity-related cancers
Cancer site
Magnitude of risk
Endometrial
3.5
Esophagus (adenocarcinoma)
3.0
Kidney (renal cell)
2.5
Colorectal
2.0
Pancreas
1.7
Breast (postmenopausal)
1.5
WCRF / AICR 2007; Calle & Kaaks 2004
Adipose tissue is a source of estrogen
Estrogen
Cytokines:
TNF-alpha
Interleukin 6
Adipokines:
Resistin
Adiponectin
Prothrombotic mediators:
PAI-1
Adapted from J. Plutzky
Adiposity and Cancer
Adiposity
Exposure
Mechanisms
Growth
factors
Insulin
resistance
IGF-1
C-Peptide
IGFBP-3
HbA1c
Chronic
inflammation
Steroid
hormones
Gene
variants
Biomarkers
Endpoint
CRP
TNF-α
Cancer
Estrogen
SHBG
BMI and endometrial cancer
3.5
Relative Risk
3
2.5
2
1.5
1
0.5
0
<25.0
25.0-29.9
BMI
Chang et al 2007
30.0+
BMI and postmenopausal breast cancer
by tumor stage
3
2.5
advanced stage
non-advanced stage
p interaction = 0.009
2
1.5
1
0.5
<25.0
25.0-29.9
30.0-34.9
BMI
Ahn et al 2007
35.0+
Insulin resistance in colon
carcinogenesis
Adiposity
Insulin
resistance
Colon cancer
BMI and colon cancer in women
by measure of body size
p=0.40
p=0.002
1.6
1.4
1.2
Q1
Q2
Q3
Q4
Q5
1
0.8
0.6
0.4
0.2
0
BMI
Pischon et al 2006
Waist-to-hip ratio
Adiposity and Cancer
Areas of future research
ƒ
Interaction with exercise (‘fat versus fit’)
ƒ
Cancer prognosis and survival
ƒ
Underlying biologic mechanisms
Thematic fields in public health
Methods:
– Epidemiology
– Biostatistics
– Qualitative methods
Physical,
chemical, and
biological
environment and
health
Cross-disciplinary themes:
– Strategy making
Social
environment and
health
– Philosophy and ethics
– Literature evaluation
– Project development
– IT use
Health policy,
organisation,
management, and
economics
ASPHER European Public Health Core
Health promotion
and prevention