Transcript Epidemiology of Cancer (Environmental Biology of Cancer)

Epidemiology of Cancer
(Environmental Biology of
Cancer)
Folder Title: Epidemio
Updated: January 29, 2013
EpiTitle
Epidemiology of Diseases
Distribution of patterns of health and disease.
Determination of potential causation that leads to the observed
distribution.
Observational vs Experimental Sciences:
• Observe episodes of disease appearance (e.g. geographic "hotspots" or occupational or familial patterns)
• Retrospective analysis of potential causative associations
• Prospective trials to determine causative sources
Determine "Relative Risk" or "Odds Ratio"
• Small vs large Relative Risk Values
Association or Correlation is not Causation
Complications in Epidemiological Observations
Reliable reproducible data and conclusions vs.
firmly held beliefs or "common sense" assumptions.
Problems with acquisition of data and data reliability:
• Time patterns of exposure vs appearance of disease
• Combinations of causative sources and sequences of
exposures
• High background appearance (non-rare diseases)
• Usually small impact of an agent on an individual or
population
• Retrospective data: recall bias and data reporting
• Prospective trials: Costs, ethical problems, subject
cooperation
Deducing Actual Causation from Epidemiological Data
Epidemiological data comparing high and low incidence rates based on
different population groups poses the questions:
1.
Why is one group presenting high risk for a given type of cancer?
2.
Why is another group presenting relatively low risk for that type of
cancer?
3.
What does that tell us about causation?
4.
Does that present possibilities for prevention and diagnosis?
Breast Cancer
Relative Risks
Epidemiological data comparing high and low
incidence rates based for different types of cancer
based on different countries poses the questions:
1. Why is a given cancer (e.g. liver cancer) high in
one set of countries?
2. Why is that same cancer very low in other
countries?
3. What does that tell us about causation?
4. Does that present possibilities for prevention and
diagnosis?
Table 2.5 part 1 of 2 The Biology of Cancer (© Garland Science 2007)
p. 44
Solar exposure & skin pigmentation
?
Epstein-Barr Virus Association
?
Hepatitis B Virus
Papilloma viruses
Papilloma viruses
Helicobacter pylori infection
Smoking
?
?
Table 2.5 part 1 of 2 The Biology of Cancer (© Garland Science 2007)
p. 44
Please respond to this question as a fill-in-the-blank question using the
directions provided in the hand-outs.
Liver cancer is greatly elevated in Hong Kong and in
other places in South East Asia. This is due to
0 of 100
There is elevated risk of breast cancer depending on whether a
woman has had a baby or not, and depending on how many
babies she has had. What does this suggest as a plausible
response to reduce the risk of death from breast cancer?
1.
2.
3.
4.
5.
6.
Get pregnant as often as possible.
Monitor and control hormonal status.
Deny the evidence and don’t worry about it.
Eat a low fat diet.
Monitor the high risk group more stringently than the lower risk
group.
Carry out ovariectomy as early in adult life as possible.
0 of 100
Epidemiological Data can also sometimes
provide clues about the biological mechanisms
underlying certain types of cancers.
Malignant Melanoma
(Solar radiation exposure)
Burkitt’s Lymphoma
(Co-infection with virus transmitted by
mosquitos also transmitting malaria)
Lifetime Melanoma Risk: 1935 to 1996
Figure 7-8, Biological Basis of Cancer, 1998, p 194
MelRisk
White Males
White Females
Black Males
& Females
MelRace
Cancer Incidence and Changes in Gene
Expression:
Reciprocal Translocation
9 to 22 Reciprocal Translocation:
Chronic Myelogenous Leukemia (CML)
8 to 14 Reciprocal Translocation:
Burkitts Lymphoma
Fluorescent in
situ
hybridization
(FISH) of
normal
metaphase
human
chromosomes
using
chromosome
specific DNA
probes with
different
fluorescent dyes
Figure 1.11b The Biology of Cancer (© Garland Science 2007)
Chromosome-specific Probe Analysis of Reciprocal Translocation (9 to 22)
in Chronic Myelogenous Leukemia
Chromosome 9 (White); Chromosome 22 (Purple)
Figure 2.23b The Biology of Cancer (© Garland Science 2007)
Reciprocal translocation between
chromosomes 9 and 22 produces fusion of
a cancer-inducing gene, the abelson or abl
gene with information on another
chromosome and gives fusion protein
involving the abl gene product that is misexpressed and drives cell division in
leucocytes leading to chronic myelogenous
leukemia.
Reciprocal Translocation (8 to 14) in Burkitt’s Lymphoma
Figure 4.13a The Biology of Cancer (© Garland Science 2007)
p. 109
Incidence of Burkitt’s Lymphoma in Relation to Infectious Disease Etiology:
Aedes simpsoni mosquito transmission vector for malaria
and Epstein Barr Virus co-infection
Figure 4.12 The Biology of Cancer (© Garland Science 2007)
Myc Oncogene (Chromosome 8) Expression Controlled by Fusion with
Immunoglobulin Heavy Chain Gene (Chromosme 14) in Burkitt’s Lymphoma
Figure 4.13b The Biology of Cancer (© Garland Science 2007
p. 109)
Burkitt’s Lymphoma is Associated with co-infection with a
virus carried by mosquitos. This is because the virus:
0 of 100
0%
0%
t..
.
...
es
a
po
gh
Se
cr
et
hi
uc
es
a
In
d
rn
s
of
fa
ca
.
nt
i..
Tu
0%
...
0%
te
sa
ct
iv
a
A
C
au
se
sp
oi
nt
m
...
1. Causes point mutations
2. Activates antibody synthesis
3. Turns off a cancer suppressor
gene
4. Induces a high fever
5. Secretes a potent chemical 0%
carcinogen
What is this slide showing?
(Short answer question)
0 of 100
Epidemiology of Cancer
Based on Age
AgeEffct
Incidence of Various Kinds of Cancers in Men and Women as a Function of Age
See Figure 11.1, Cancer incidence at various ages for men and women. p. 400. Weinberg.
Note maximum incidence per 100,000 population at about age 70, then drop off after that age.
Serious incidence begins around age 35 except for breast cancer which can have an earlier onset
depending on genetics.
Cancer in children and younger adults has an
incidence rate of 11% of the total cancers, but accounts
for only 5% of the total cancer deaths. Why is that the
case? What does that difference between incidence and
mortality tell us about cancers in younger persons?
(This is a fill-in-the-blank question. Keep it brief. You
can use abbreviations if they are clear).
0 of 100
Specific Cancer Incidence
and Migratory Patterns:
Cancers and
Environmental Effects
See also Figure 7-6,
Biological Basis of Cancer,
p 191
EatFat
Cancer Incidence Following Migration
Figure 2.20 The Biology of Cancer (© Garland Science 2007)
p. 45
(When this slide opens you do not have to send in your name under “Send
User Data” unless you borrowed a Response Card from us this morning.
If you borrowed a Card be sure to remove the previous name and enter
your names.
The two previous slides show patterns of cancer
incidence within one or two generations in populations
of persons who have migrated .
What do these data tell us about causation of these
cancers?
You can abbreviate as long as I reasonably can figure
out your meaning.
0 of 100
Cigarette Consumption and Lung Cancer: 1880 to 2000
Figure 11.2 The Biology of Cancer (© Garland Science 2007)
Carcinogenic Agents
and co-Carcinogenic
Agents:
Interacting Causations
CigDose
p. 46
Table 2.6 The Biology of Cancer (© Garland Science 2007)
CigBooze
Environmental and
Occupational
Cancers
CxCauses
WorkCx
Journal of the
National Cancer
Institute,
July, 1996
Kids&Rad
Cultural Associations
and Specific Cancers
Journal of the National
Cancer Institute
October, 1996
StomCxEthnic
Table 2.7 The Biology of Cancer (© Garland Science 2007)
p. 47
Detailed analysis of the epidemiology of cancers is
important in cancer medicine because it helps us to
understand
__ ___ ___ ___ ___ ___
(or to)
__ __ __ __ __ __ __ some cancers
You only need one response
0 of 100
Cancer in children 0 to 14 years of age occurs in 15 per
100,000 as the incidence rate. Cancers in that same group
accounts for 2.5 deaths per 100,000. What does that tell us
about cancers that affect children ages 0 to 14?
(This is a fill-in-the-blank question. Keep it brief. You can
use abbreviations if they are clear).
0 of 100
Male Cancer Death Rates for Various Carcinomas, 1939 to 1947. Log-Log Plot
Figure 11.3 The Biology of Cancer (© Garland Science 2007)
Slope of 5 indicates a series of rate limiting steps
Cancer Incidence and Carcinogen Exposure
Mesothelioma in
human insulation
workers
Squamous cell
carcinoma in mice.
Figure 11.4 The Biology of Cancer (© Garland Science 2007)
Understanding the epidemiology of cancers allows us
not only to understand the causes of some cancers but
also helps us to design programs for the
_ _ _ _ _ _ _ _ _ _ of some cancers.
One word only!
0 of 100